Showing papers in "Endocrinology in 1963"
TL;DR: It was found that cutting, stretching or burning the recurrent laryngeal nerves resulted in respiratory difficulty and retarded the fall in serum calcium after parathyroidectomy—results similar to those produced by thyroparathyroid surgery.
Abstract: The extent and time course of the hypocalcemia developing in calcium-depleted young male rats during the first 5 hr after parathyroidectomy were found to differ considerably, depending on which one of 3 methods of parathyroidectomy was used. One hr after the operation the serum calcium of thyroparathyroidectomized rats was higher than that of rats parathyroidectomized alone, whether by excision or hot-wire cautery. By the fifth hr, the serum calcium of rats parathyroidectomized by cautery had fallen much lower, that of rats parathyroidectomized by excision had changed very little, and that of thyroparathyroidectomized rats had decreased, but only to the level of the rats parathyroidectomized by excision. It was found that cutting, stretching or burning the recurrent laryngeal nerves resulted in respiratory difficulty and retarded the fall in serum calcium after parathyroidectomy—results similar to those produced by thyroparathyroidectomy. It was concluded that trauma to these nerves, which is unavoidable ...
327 citations
TL;DR: Testosterone replacement lowered both ACTH content and adrenal weight to control levels and estradiol administration increased it further, together with Gonadectomy and Adrenalectomy together, which increased pituitary ACTH Content.
Abstract: Gonadectomy in male rats impaired growth but increased pituitary and adrenal weight and adrenal RNA and DNA content. Pituitary ACTH content increased also. Testosterone replacement lowered both ACTH content and adrenal weight to control levels. Estradiol administration increased pituitary ACTH without a further increment in adrenal weight. Gonadectomy and adrenalectomy together increased pituitary ACTH content compared with adrenalectomy alone. Under these conditions, testosterone replacement reduced pituitary ACTH and estradiol administration increased it further. Plasma corticosterone (Cpd. B) concentrations in castrated males at rest, after stress or after ACTH injection did not differ from those observed in intact controls. Biological half-life in vivo was shortened and hepatic inactivation of steroid in vitro was increased. Steroid production by adrenal slices in vitro was diminished by castration, and the output of steroid in adrenal venous blood also decreased. Increased steroid secretion was produ...
293 citations
TL;DR: Two to 3 weeks following gonadectomy, pituitary LH content had risen significantly in both adult females and immature males, whereas it remained unchanged in immature females and adult males, while plasma LH activity increased significantly in all gonadectomized groups.
Abstract: A careful study of some factors influencing LH secretion and storage has been made in immature and adult rats of both sexes. The ovarian ascorbic acid assay for LH has been utilized throughout. The LH content of the anterior lobe was 19.8 μg/gland in immature females and 22.3 μg/gland in adults. In immature males the content (7.0 μg /gland) was lower than that in immature females and rose markedly to a value of 32.9 μg/gland in adults, a value which was greater than that found in adult females. No detectable LH was found in plasma from rats with intact gonads except in the case of adult males, in which minimal levels were detectable. Two to 3 weeks following gonadectomy, pituitary LH content had risen significantly in both adult females and immature males, whereas it remained unchanged in immature females and adult males. By contrast with the variable response to gonadectomy seen in the hypophysis, plasma LH activity increased significantly in all gonadectomized groups. When expressed on a weight basis, e...
261 citations
TL;DR: The present investigation compares the adipokinetic activity of these hormones in the rabbit, guinea pig hamster, rat, pig and dog by measuring the effect of various concentrations of hormone upon the production of free fatty acids by slices of perirenal adipose tissue incubated in Krebs-Ringer phosphate solution.
Abstract: Several naturally occurring polypeptide and amine hormones possess adipokinetic activity. The present investigation compares the adipokinetic activity of these hormones in the rabbit, guinea pig hamster, rat, pig and dog. Activity was assayed by measuring the effect of various concentrations of hormone upon the production of free fatty acids (FFA) by slices of perirenal adipose tissue incubated in Krebs-Ringer phosphate solution. As described by previous investigators, when the medium does not contain albumin, the FFA produced by lipolysis accumulate only within the tissue slice; when albumin is present in the medium, the FFA produced by lipolysis accumulate in the medium as well as in the tissue slice. In the albumin- free assay system, the concentration of FFA in the tissue after 3 hours' incubation is linearly related to the logarithm of the concentration of hormone in the medium. The following 6 components of the pituitary gland possess adipokinetic activity upon the adipose tissue of one or more mamm...
180 citations
TL;DR: The LH-releasing effect of crude acidic extracts of rat stalk-median eminence tissue was evaluated in chronically ovariectomized rats in which LH secretion had been partially blocked by injection of estrogen and progesterone.
Abstract: The LH-releasing effect of crude acidic extracts of rat stalk-median eminence tissue was evaluated in chronically ovariectomized rats in which LH secretion had been partially blocked by injection of estrogen and progesterone. Ten min after intravenous administration of these extracts a significant increment in plasma LH was detectable, as measured by the ovarian ascorbic acid depletion test. The minimal effective dose (MED) of stalk-median eminence extract was approximately 40 μg wet weight of tissue extracted. By contrast, cerebral cortical extract was completely inactive at doses up to 5,000 μg wet weight of tissue extracted. Pitressin was active in inducing LH release in this test at doses of 200 or more mU. Thus, the quantity of Pitressin required to produce a positive response is approximately 200–400 times greater than the quantity of vasopressin found in the MED of hypothalamic extract. The MED for epinephrine was 5 μg, a quantity several thousand times the amount present in the MED of stalk-median...
134 citations
TL;DR: It is suggested that the degree of hypothalamic alteration produced by androgen treatment is dosage-dependent, and if sterile rats were pretreated with progesterone and electrical stimulation was performed on the day of vaginal proestrus, then ovulation could be induced by stimulation of the preoptic area.
Abstract: In these studies a single injection of 10 μg of testosterone propionate at 5 days of age resulted in permanent anovulatory sterility in 96 of 136 female rats. Studies of the hypothalamic refractoriness produced by this dosage revealed that ovulation could be induced in 5 of 10 sterile rats by electrical stimulation of the median eminence, whereas preoptic-suprachiasmatic stimulation was ineffective. However, if sterile rats were pretreated with progesterone and electrical stimulation was performed on the day of vaginal proestrus, then ovulation could be induced by stimulation of the preoptic area. These findings differ from those in rats sterilized by comparable administration of 1.25 mg of androgen. It is suggested that the degree of hypothalamic alteration produced by androgen treatment is dosage-dependent.
125 citations
TL;DR: It is suggested that no major alteration in secretory activity of the ovary need occur to account for both the transiency of uterine sensitivity and the resulting decidual growth observed in the pseudopregnant rat.
Abstract: A study of the action of estrogen and progestogen on the onset, magnitude and duration of responsiveness (sensitivity) of the uterus to traumatization in the rat revealed that, in animals ovariectomized after estrus, maximal sensitivity could not be achieved by injection of progesterone alone, but was observed when both estrone and progesterone were administered simultaneously. The timing of the onset, magnitude and duration of sensitivity observed in the intact pseudopregnant rat was reproduced in rats ovariectomized after estrus by daily injections of estrone and progesterone in dosages identical with those necessary for optimal growth and maintenance of the resulting deciduomata. It is suggested that no major alteration in secretory activity of the ovary need occur to account for both the transiency of uterine sensitivity and the resulting decidual growth observed in the pseudopregnant rat. Although estrone potentiated the ability of progesterone to promote the sensitive state in the uterus, it inhibit...
114 citations
TL;DR: Increased output of both steroids was attended by a rise in the progestin content of the ovaries; the output could be attributed, therefore, to increased synthesis rather than to release from a preformed store.
Abstract: Progesterone and 20α-hydroxypregn-4-en-3-one (β4-3-ketopregnene-20α-ol), an active progestin closely related in structure to progesterone, were measured in New Zealand white rabbit ovaries and ovarian vein blood by physicochemical methods described in detail. Coitus or the injection of ovulatory dosages of pituitary or placental gonadotropins caused marked elevations in progestin output. Single injections of other pituitary tropins were ineffective, with the exception of growth hormone, which stimulated the output of the steroids under certain conditions. The 20α-OH steroid (20α-hydroxypregn-4-en-3-one) was produced in quantities approximately 10-fold greater than progesterone. Increased output of both steroids was attended by a rise in the progestin content of the ovaries; the output could be attributed, therefore, to increased synthesis rather than to release from a preformed store. The amounts of both progestins released could be correlated positively with the size and maturity of the ovary. Their sour...
107 citations
TL;DR: In spayed rats, intrapituitary ovarian grafts or estrogenic depots caused castration cells to regress in localized regions, suggesting that direct but localized effects of intrahypothalamic hormone depots may fail to influence enough pituitary tissue to permit the change to be detected at the periphery.
Abstract: In spayed rats, intrapituitary ovarian grafts or estrogenic depots caused castration cells to regress in localized regions. The volume of tissue affected was proportional to the estrogen concentration of the depot. Intrahypothalamic pellets tended to reduce the size, but not the population density, of the castration cells, but only at higher doses. These slight effects were not localized, however. These findings suggest that direct but localized effects of intrapituitary hormone depots may fail to influence enough pituitary tissue to permit the change to be detected at the periphery. The possibility that a hormone can act directly casts doubt upon the interpretation that the effects of intrahypothalamic hormone depots reveal an indirect feedback pathway—via neural “receptors.” Intrahypothalamic administration may merely be the most efficient method of distributing a compound to the entire adenohypophysis. The pertinence of this “implantation paradox” is discussed in relation to the large body of work aime...
106 citations
102 citations
TL;DR: Thyroxine secretion rate has been estimated in the rat using the radioactive thyroxine turnover technique, and the fractional turnover rate is greater in female than in male rats, both in the Osborne- Mendel strain of age 2–3 months and the Wistar strain of 12 months.
Abstract: Thyroxine secretion rate has been estimated in the rat using the radioactive thyroxine turnover technique. The influences of age and sex have been examined. The thyroxine turnover technique gives values which are comparable with those obtained with methods using thyroxine replacement and restoration of basal metabolic rate, pituitary morphology, blood thyrotropin concentration in thyroidectomized rats, and with measurements based on intrathyroidal thyroxine turnover. In contrast with older methods, the turnover technique measures only thyroxine degradation, not the thyroxine equivalent of the biological effectiveness of secreted thyroxine and triiodothyronine, heretofore referred to in the literature as the “thyroxine secretion rate.” The fractional turnover rate is greater in female than in male rats, both in the Osborne- Mendel strain of age 2–3 months and the Wistar strain of 12 months. Thyroxine degradation per unit body weight is greater in females than males only in the latter group. The distributio...
TL;DR: It is concluded that, once maximal sensitivity has been acquired, the endometrium loses its capacity for another response during pseudopregnancy or pregnancy.
Abstract: The duration of uterine sensitivity (ability to produce a deciduoma) was determined for several strains of pseudopregnant rats using the method of endometrial scratching. The day of maximal sensitivity was found to be related to the last ovulation and not to the day on which the pseudopregnancy was initiated. It occurred on Day 4, a day associated with increased uterine weight and water content, and was markedly reduced or absent 24 hr later, depending on the strain of rat. It was not possible to prolong sensitivity to Day 5 by: a) physiologic lengthening of pseudopregnancy, b) administration of hormones associated with pseudopregnancy, or c) daily blockade of the CNS by pentobarbital. It is concluded that, once maximal sensitivity has been acquired, the endometrium loses its capacity for another response during pseudopregnancy or pregnancy. This concept of maximal sensitivity contributes to our understanding of some of the results obtained by earlier investigators.
TL;DR: It is concluded that the pineal polypeptide is arginine vasotocin or a hormone with similar structure.
Abstract: A polypeptide with pressor and oxytocic activities has been isolated from bovine pineal gland. This polypeptide is neither arginine—or lysine—vasopressin, nor oxytocin. The biological and chromatographic characteristics are similar to those of arginine vasotocin. It is concluded that the pineal polypeptide is arginine vasotocin or a hormone with similar structure.
TL;DR: To determine the type of inhibition of 11β-hydroxylation produced by Metopirone, deoxycorticosterone-4-C14 was incubated with rat adrenal homogenates and results indicated pure competitive inhibition within the limits of error of the method.
Abstract: To determine the type of inhibition of 11β-hydroxylation produced by Metopirone, deoxycorticosterone-4-C14 was incubated with rat adrenal homogenates in a medium of 50% bovine blood serum, 50% Krebs bicarbonate buffer, pH 7.4, containing an excess of TPNH, and the production of corticosterone and 11-dehydrocorticosterone was measured. Different concentrations of substrate and Metopirone were used. The data were plotted according to Lineweaver and Burk and according to Dixon. The results indicated pure competitive inhibition within the limits of error of the method. Metopirone did not inhibit 21-hydroxylation significantly under the same conditions.
TL;DR: Although testosterone alone can restore spermatogenesis to a limited extenuating circumstances, the testes of animals given TP+STH or TP+ STH+T4 for 35 days were heavier than those of animals receiving TP alone, and a few of the seminiferous tubules contained maturation phase sperMatids.
Abstract: The ability of testosterone propionate (TP) to restore spermatogenesis was investigated in 67- to 70-day hypophysectomized rats administered TP either separately or in combination with somatotrophin (STH) and/or thyroxine (T4). Following TP treatment for 35 days, the testicular weights had increased to twice those of the hypophysectomized controls, and a few of the seminiferous tubules contained germinal cells as mature as acrosome phase spermatids. With more prolonged therapy (90–110 days), spermatogenesis was restored qualitatively but not quantitatively in 33% of the animals, while the remainder of the animals showed varying degrees of response. The testes of animals given TP+STH or TP+STH+T4 for 35 days were heavier than those of animals receiving TP alone, and a few of the seminiferous tubules contained maturation phase spermatids. Treatment for 90–110 days completely restored spermatogenesis in ½ of these animals. Consequently, although testosterone alone can restore spermatogenesis to a limited ext...
TL;DR: It is suggested that inhibition of lipid synthesis may be causally related to many of the previously noted effects of growth hormone on lipid metabolism.
Abstract: Treatment of hypophysectomized rats with ovine growth hormone (1 mg /rat/day for 4 days) results in a decrease in the ether-extractable material in both epididymal and omental adipose tissue. Concomitantly, the ability of adipose tissue obtained from these animals to synthesize lipid in vitro from uniformly labeled glucose or leucine-2-C14 is reduced by a factor of at least 3. The oxidation of glucose to CO2 is also reduced, but the formation of CO2 from leucine is unaffected. It is suggested that inhibition of lipid synthesis may be causally related to many of the previously noted effects of growth hormone on lipid metabolism.
TL;DR: The purpose of the electron microscopic study is to observe and make clear the interrelationship between the mitochondria and the other organelles in the adrenal cortex in situ from the standpoint of the biosynthesis of steroid hormones.
Abstract: The purpose of our electron microscopic study is to observe and make clear the interrelationship between the mitochondria and the other organelles in the adrenal cortex in situ from the standpoint of the biosynthesis of steroid hormones. The results are summarized as follows: The mitochondria are divided into 3 types: the ‘I,’ the ‘Intermediate’ and the ‘Ila, b’ types. The mitochondria of the I type have a lamellar structure or membranelike projections. The Ha type mitochondria appear as a honeycomblike structure in a horizontal section, and each of them contains many microtubules. On the other hand, there are some mitochondria in which a few microtubules fuse due to the disappearance of their mutual partitions, and they are named the lib type. By ACTH administration, Ila type mitochondria increase in size and number, and, at more advanced stages, the open-form mitochondria increase. The endoplasmic reticulum is developed markedly by ACTH administration. On the contrary, following hypophysectomy, the mito...
TL;DR: A single large dose of thyroxine has no effect on the uptake, binding or release of H3- epinephrine by the heart, or the hypertensive response induced by a given dose of the neurohumor.
Abstract: Hyperthyroid rats show an elevated and prolonged hemodynamic response to injected epinephrine; hypothyroid rats have lower base-line blood pressures than control animals, but show a normal response to the catecholamine. Hyperthyroid rats shunt a larger fraction of the cardiac output to their enlarged hearts, thus delivering a greater proportion of a dose of H3-epinephrine to this organ. Each gram of hyperthyroid heart receives the same fraction of circulating H3-epinephrine as an equal weight of normal heart, but its capacity to inactivate the H3-epinephrine by binding is diminished. The consequent maintenance of elevated levels of free epinephrine may be a major factor in the development of the altered hemodynamic response of the hyperthyroid animal to epinephrine. A single large dose of thyroxine has no effect on the uptake, binding or release of H3- epinephrine by the heart, or the hypertensive response induced by a given dose of the neurohumor. Hypothyroid hearts receive and bind as much circulating e...
TL;DR: Estradiol administration reversed previously reported sex differences in adrenal secretion and peripheral metabolism of corticosterone and shortened the biological half-life of Cpd.
Abstract: Two weeks after a single injection of polyestradiol phosphate, pituitary weight more than doubled in both male and female rats. Pituitary ACTH content was unchanged in the males but increased 2.5-fold in the female animals. Pituitary RNA and DNA increased in the male rats, whereas only RNA increased in the females. Adrenal weight was increased only in male rats, associated with an increase in adrenal RNA. Adrenal RNA and DNA in female rats were both decreased. Estradiol administration reversed previously reported sex differences in adrenal secretion and peripheral metabolism of corticosterone (Cpd. B). Plasma Cpd. B concentrations after stress or ACTH were increased in treated male rats and unchanged in females. In male animals, estradiol increased hepatic reduction of ring A of Cpd. B in vitro and shortened the biological half-life of Cpd. B in vivo. Converse effects were obtained in females. Following estradiol administration in vivo or after its direct addition in vitro, steroidogenesis was stimulated ...
TL;DR: Cerebral and pituitary involvement in the feedback regulation of ACTH secretion was investigated by stereotaxic placement of single or double implants of crystalline hydrocortisone acetate in the brain or pituitsary of male rats, which resulted in abolition of CAH and in atrophy of the remaining adrenal.
Abstract: Cerebral and pituitary involvement in the feedback regulation of ACTH secretion was investigated by stereotaxic placement of single (roughly 0.2 mg) or double implants of crystalline hydrocortisone acetate in the brain or pituitary of male rats. Compensatory adrenal hypertrophy (CAH) was measured 9–10 days following unilateral adrenalectomy. Single hydrocortisone implants in the median eminence and the anteromedial hypothalamus resulted in abolition of CAH and in atrophy of the remaining adrenal. Ventral prostate weights in these rats were decreased somewhat, but testicular, thyroid and pituitary weights were unchanged, and prostatic, testicular and thyroid histology was normal. Hydrocortisone implants in the lateral basal hypothalamus produced only partial inhibition of CAH, and cholesterol implants in the median eminence had no effect. Single hydrocortisone implants in the pituitary gland were likewise ineffective, as were 3 of 4 double implants in the pituitary. Normal CAH followed single anterior fore...
TL;DR: N-acetylation of the terminal serine resulted in a peptide which caused a marked reduction in all the activities studied, both adrenal and extra-adrenal.
Abstract: Several peptides in which the N-terminal serine of corticotropin has been altered have been assayed relative to unaltered corticotropin A1 for their biological activities, both adrenal and extra-adrenal. The adrenal activities assayed were in vivo steroidogenesis in 24-hr hypophysectomized rats and in vitro steroidogenesis by quartered rat adrenals. The in vitro release of free fatty acids by rat epididymal adipose tissue and the hypoglycemic effect in the intact mouse were the extra-adrenal activities assayed. Oxidative deamination of the free a-amino group by periodate was accompanied by a reduction of in vitro steroidogenic and lipolytic activity to 10%. in vivo steroidogenesis was more markedly reduced (to 1–2%) while in vivo hypoglycemia was greater than expected (32 %). Replacement of the N-terminal serine by an N-terminal glycine did not alter any of the measured activities. N-acetylation of the terminal serine resulted in a peptide which caused a marked reduction in all the activities studied. Thu...
TL;DR: Doses of oxytocin and vasopressin that significantly reduced the FFA of the plasma produced a small increase in blood glucose, while the dose of insulin that was similarly effective produced no significant change in the blood glucose concentration.
Abstract: The intravenous injection of oxytocin or 8-lysine-vasopressin at a rate of 2 ×10-5 pinoles per kg per hr produced a significant decrease in the concentration of the FFA of the plasma of nondiabetic and alloxandiabetic dogs. A similar decrease was not produced in the nondiabetic dog with less than 3O×1O-5 pinoles insulin per kg per hr. The alloxan-diabetic dog, however, appeared to require a smaller dose of insulin to induce the same decrease in the plasma FFA. The reduction of the plasma FFA was independent of an increased removal of glucose from the blood. Doses of oxytocin and vasopressin that significantly reduced the FFA of the plasma produced a small increase in blood glucose, while the dose of insulin that was similarly effective produced no significant change in the blood glucose concentration.
TL;DR: By using the epididymal fat pad from rats fed a fatfree diet for 7 days and weighing 160–180 g, the procedure for assaying insulin was greatly improved: the magnitude of the CO2 measurement was doubled, the response was more uniform, and the accuracy was increased by the smaller amount of insulin which was required to give a maximal in vitro insulin response.
Abstract: The in vitro response of epididymal adipose tissue to insulin is conditioned by the type of diet fed. The epididymal fat pad of the rat responded to the feeding of a fat-free diet by: 1) an increased endogenous metabolism, as reflected by a 50 % increase in oxygen consumption, 2) an increased capacity for fatty acid synthesis, as reflected by a doubling of the net excess CO2 production in the presence of excess insulin, and 3) the same sensitivity to minimal quantities of insulin (25 μU), but a much greater sensitivity to larger amounts of insulin. Approximately 10 times as much insulin was required to give a maximal in vitro insulin response when the rats were fed chow. By using the epididymal fat pad from rats fed a fatfree diet for 7 days and weighing 160–180 g, the procedure for assaying insulin was greatly improved: the magnitude of the CO2 measurement was doubled, the response was more uniform, and the accuracy was increased by the smaller amount of insulin which was required to give a maximal respo...
TL;DR: Paired samples of rat epididymal adipose tissue were incubated in bicarbonate buffer in the presence of glucose and dl-leucine-2-C14 and ovine prolactin in high doses was found to stimulate the conversion of leucine to fatty acids, and porcine, ovine and human growth hormone preparations had similar effects.
Abstract: Paired samples of rat epididymal adipose tissue were incubated in bicarbonate buffer in the presence of glucose and dl-leucine-2-C14. Bovine growth hormone added to the incubation medium at a concentration of 1 μg/ml doubled the conversion of leucine-C14 to fatty acids in adipose tissue from hypophysectomized rats. Porcine, ovine and human growth hormone preparations had similar effects. However, no such stimulation of leucine metabolism was seen when adipose tissue from normal rats was used. Corticotropin, thyrotropin and oxytocin had no effect on leucine metabolism, but ovine prolactin in high doses (25–100 μg) was found to stimulate the conversion of leucine to fatty acids. Growth hormone also increased the uptake of leucine from the incubation medium but did not influence the oxidation of leucine to CO2.
TL;DR: The sera of 25 vertebrate species from the vertebrate classes Pisces, Amphibia, Reptilia, Aves and Mammalia, and including representatives of the orders Lagomorpha, Rodentia, Carnivora, Perissodactyla, ArtiodactylA and Primates, exhibited binding activity which was temperature-dependent and sensitive to heating.
Abstract: The sera of 25 vertebrate species from the vertebrate classes Pisces, Amphibia, Reptilia, Aves and Mammalia, and including representatives of the orders Lagomorpha, Rodentia, Carnivora, Perissodactyla, Artiodactyla and Primates from the class Mammalia, have been examined for the presence of a specific corticosteroid-binding protein Binding activity was assayed by means of gel nitration on Sephadex G-50 The amount of binding at 4 and 37 C was assayed and the sensitivity of binding to heating at 60 C was determined The sera of all species examined exhibited binding activity which was temperature-dependent and sensitive to heating A small-scale purification procedure for human corticosteroid-binding globulin on hydroxylapatite is described and its applicability to the cortisol-binding protein of 7 other species is demonstrated
TL;DR: The adrenal ascorbic acid concentration in fetal rats was about 400 mg/100 g the day before parturition, and fell to about 350, returned to 400 on days 1 and 2 postnatally, and then fell precipitously to 210 on day 3, from which low point it rose slowly in 10 days to 310 mg/ 100 g.
Abstract: The adrenal ascorbic acid concentration in fetal rats was about 400 mg/100 g the day before parturition. At birth it fell to about 350, returned to 400 on days 1 and 2 postnatally, and then fell precipitously to 210 on day 3, from which low point it rose slowly in 10 days to 310 mg/100 g. During this time, depletion of the adrenal ascorbic acid concentration due to stress occurred the last day prenatally and not again until the 4th day postnatally. In the same rats the plasma concentration of corticosterone was 21 μg/100 ml on the last prenatal day and at birth. It fell slightly to 18 μg/100 ml on postnatal days 1, 2 and 3, and to 10 μg on day 4, where it remained. Stress produced significant increases of the corticosterone concentration in plasma on the last prenatal day, at birth, and not again until the 4th postnatal day. Corticosterone concentration in plasma in the mother was twice that in the fetuses (40 μg and 21 μg/100 ml). Adrenalectomy of the mother reduced her plasma concentration of corticoste...
TL;DR: There are 2 different generations of Leydig cells in the testis of the rat, as revealed by the histochemistry of 4 enzyme systems and of lipids studied.
Abstract: The histochemistry of 4 enzyme systems (nonspecific esterase, DPNH, β-hydroxybutyrate and steroid-3β-ol dehydrogenases) and. of lipids has been studied in the Leydig tissue of the rat from the 3rd to the 50th postnatal day. The distribution and form of the Leydig cells as revealed by these reactions were different in the prepubertal period as compared with maturity. In both, the Leydig tissue exhibited all the enzyme activities. The number of positive cells diminished rapidly during the 1st postnatal week but more slowly during the 2nd and 3rd weeks. At puberty, enzymatically active Leydig cells appeared evenly distributed in the intertubular tissue. Prepubertal Leydig cells contained sudanophilic lipid material, whereas those of the mature animal did not exhibit any stainable lipids. On the basis of these results and some earlier observations, it is concluded that there are 2 different generations of Leydig cells in the testis of the rat.
TL;DR: The ability of TRF to stimulate TSH release in vitro was inhibited by in vivo pretreatment or in vitro preincubation with L-thyroxine, and TRF does not act by inhibiting destruction of released TSH nor by potentiating TSH in the bioassay.
Abstract: Identical populations of anterior pituitary tissue were obtained by separating rat anterior pituitary in halves or quarters. When incubated in vitro in Krebs-Ringer bicarbonate glucose buffer, such identical fragments of pituitary released identical minute amounts of TSH into the incubation fluid. Addition of hypothalamic TSH-releasing factor (TRF) of sheep origin (prepared by molecular sieving and characterized with an in vivo bio-assay) increased the amount of TSH present in the incubation fluid of the experimental pituitary population when compared to its control. The stimulation of TSH release was a linear function of the log of the dose of added TRF. The ability of TRF to stimulate TSH release in vitro was inhibited by in vivo pretreatment or in vitro preincubation with L-thyroxine. TRF does not act by inhibiting destruction (in vitro) of released TSH nor by potentiating TSH in the bioassay. LRF (LH-releasing factor), CRF (corticotropin- releasing factor), lysine-vasopressin, oxytocin, α-MSH and β-MS...
TL;DR: Data are in accord with the conclusion that the hyperglycemic response to glucagon is the resultant of the combined effects of rapid hepatic glycogenolysis and stimulation of the release of epinephrine, which acts to depress the rate of glucose uptake by peripheral tissues.
Abstract: A single injection of glucagon (50 μg/kg) given to anesthetized dogs rapidly elevates glucose, lactate and epinephrine levels in peripheral plasma. A 10-min infusion of glucagon (0.1 mg/min) produced a marked elevation of both epinephrine and norepinephrine in adrenal vein blood. These data are in accord with the conclusion that the hyperglycemic response to glucagon is the resultant of the combined effects of rapid hepatic glycogenolysis and stimulation of the release of epinephrine, which acts to depress the rate of glucose uptake by peripheral tissues. Evidence for the postulate that hypoglycemia stimulates release of glucagon, which in turn elicits the release of epinephrine, is discussed.
TL;DR: Administration of cortisol appeared to result in increased concentration of virtually all amino acids and urea in both fasted and nonfasted animals, and the difference between the sums of amino acids present was significant.
Abstract: Effects of cortisol administration on concentrations of free amino acids and other ninhydrin reacting substances (NRS) were determined in plasma of fasted mice and skeletal muscle of fasted and nonfasted mice by column chromatography. The following amino acids were found: alanine, arginine, aspartic acid, glutamic acid, glycine, glutamine, histidine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, tryptophan and valine. Cystine and cysteine were absent and traces of phenylalanine and tyrosine were present. Non-amino acid NRS found included carnosine, glycerophosphoethanolamine, phosphoethanolamine, phosphoserine, taurine and urea. Taurine accounted for more than half the total NRS. Administration of cortisol appeared to result in increased concentration of virtually all amino acids and urea in both fasted and nonfasted animals. In the fed group, the difference between the sums of amino acids present was significant. Cortisol injection also increased plasma amino acids but to a lesser ...