Showing papers in "Neuroendocrinology in 1977"
TL;DR: Arginine-8-vasopressin (AVP) and oxytocin (OXT) were measured by radio-immunoassay (RIA) in cerebrospinal fluid (CSF) and plasma of Wistar rats under various conditions.
Abstract: Arginine-8-vasopressin (AVP) and oxytocin (OXT) were measured by radio-immunoassay (RIA) in cerebrospinal fluid (CSF) and plasma of Wistar rats under various conditions. In addition, basal plasma levels of OXT were measured in Brattleboro rats, either homozygous or heterozygous for diabetes insipidus (Ho-DI or He-DI respectively). The basal OXT plasma level of Ho-DI rats was elevated as compared to He-DI and Wistar rats. Water deprivation caused a gradual increase of plasma OXT levels in Wistar rats. CSF was collected from Wistar rats by withdrawal from the cisterna magna under pentobarbitone anesthesia. Anesthesia induced a rise of the plasma AVP level as well as of the plasma OXT level. Withdrawal of CSF caused a dramatic rise of plasma AVP levels and, to a minor extent, of plasma OXT levels. In rats studied at 4 weeks after hypophysectomy plasma AVP levels were only detectable after CSF withdrawal. CSF levels of AVP were elevated in these animals. In intact and hypophysectomized rats, basal OXT plasma levels and the increased levels after anesthesia were the same. The OXT release into the blood was partly impaired after hypophysectomy because CSF withdrawal did not result in a further rise of plasma OXT levels. CSF oxytocin levels were the same in intact and hypophysectomized rats. A difference of the effect of hypophysectomy was thus observed with respect to the presence in CSF and plasma for AVP but not for OXT. It is concluded that the regeneration of AVP and OXT fibers is different which leads to a different release of the hormones into CSF and plasma.
240 citations
TL;DR: An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens and Mel levels in chicken serum were determined using these RIAs.
Abstract: An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens. Anti-NAS and anti-Mel sera were produced by immunization of rabbits with NAS-M-bovine serum albumin (BSA) and Mel-M-BSA, respectively. Anti-NAS serum used in the NAS/Mel RIA reacts equally well with NAS and Mel, while anti-Mel serum used in the Mel/RIA reacts specifically with Mel. The NAS and Mel levels in the pineal and Harderian gland, the retina and the brain of rats and chickens and Mel levels in chicken serum were determined using these RIAs. Levels of NAS and Mel in the rat pineal demonstrated diurnal rhythms with high levels during the dark period and low levels during the light period. The indole levels determined in this study correlate well with those obtained by other methods.
225 citations
TL;DR: Changes of NE and DA concentration found in some individual hypothalamic nuclei under the influence of stress indicate that catecholamines (CAs), particularly in the medial basal hypothalamus, could be involved in the regulation of some neuroendocrine processes which are being activated during stress, especially ACTH release.
Abstract: Norepinephrine (NE) and dopamine (DA) concentrations in 17 individual hypothalamic nuclei and 3 other brain regions were measured in rats, acutely or repeatedly stressed by immobilization, using a microdissection technique and a radioisotopic-enzymatic assay. Following the first 20 min immobilization (IMO) a significant NE decrease in the ventromedial (NVM) and supraoptic (NSO) nuclei and a DA decrease in the arcuate nucleus (NA) as well as NE and DA increase in the dorsomedial nucleus (NDM) were seen. Repeated IMO (40 times) produced a NE increase in the NVM, NDM, NSO paraventricular nucleus (NPV) and median eminence (ME), and a DA increase in the NDM and NPV. Changes of NE and DA concentration found in some individual hypothalamic nuclei under the influence of stress indicate that catecholamines (CAs), particularly in the medial basal hypothalamus, could be involved in the regulation of some neuroendocrine processes which are being activated during stress, especially ACTH release.
120 citations
TL;DR: The suppressive effects of delta1-THC on ovulation and gonadotropin secretion were prevented by administration of gonadetropin releasing hormone 1 h after the drug, indicating that the central action was exerted on the hypothalamus and not on the pituitary gland.
Abstract: Administration of △ 1-tetrahydrocannabinol ( △ 1-THC), the principal psycho-active ingredient of cannabis, to proestrous rats (2 mg/rat, i.p.,
93 citations
TL;DR: The circadian rhythms in both food intake and plasma corticosterone (11-OHCS) in adult female rats were altered concomitantly under various lighting conditions.
Abstract: The circadian rhythms in both food intake and plasma corticosterone (11-OHCS) in adult female rats were altered concomitantly under various lighting conditions. In all lighting regimens, plasma 11-OHC
75 citations
TL;DR: The influence of thyroid hormones on monoamines (MAs) in the adult brain varies with the neurotransmitter and the brain area considered, indicating that the behavioral abnormalities associated with thyroid dysfunction in adulthood may be related to neurotransmission disturbances.
Abstract: The effects of hypo- and hyperthyroidism were investigated on brain levels and accumulation rates (after pargyline) of 5-hydroxytryptamine (5-HT), norepinephrine (NE) and dopamine (DA) in discrete bra
74 citations
TL;DR: The results indicate that Prl can depress LH release after castration and that these effects are mediated via the hypothalamus.
Abstract: Castration of male and female rats resulted in a marked rise in serum LH. The rise in serum LH was partially or completely prevented by injection of prolactin (Prl), by implantation of a small amount of Prl in the median eminence (ME), by grafting 2 anterior pituitaries (APs) underneath the kidney capsule, or by transplantation of a Prl-secreting pituitary tumor underneath the skin. The larger pituitary tumor transplants secreted more Prl and were more effective in reducing LH release than the smaller tumors which secreted less Prl. Suppression of LH release generally was greater during the earlier than in the later phases of the different treatments. The pituitary LH response to synthetic LH-RH was the same in ovariectomized rats with or without pituitary grafts, and the decrease in hypothalamic LH-RH after orchidectomy was prevented by pituitary grafts. These results indicate that Prl can depress LH release after castration and that these effects are mediated via the hypothalamus.
68 citations
63 citations
TL;DR: A functional role for the vagus nerve in normal cyclic activity, COH, and gonadotrophin (Gn) secretion is suggested in hemiovariectomized rats and rats with both ovaries intact.
Abstract: Hemiovariectomized rats were randomly assigned to 1 of 5 groups: controls, 6-hydroxydopamine (6-HD)-treated, abdominal vagotomy, 6-HD-treated plus abdominal vagotomy and pelvic parasympathectomy. 15 d
60 citations
TL;DR: The results suggest that hypothalamic factors are needed for the normal development of cells containing these pituitary hormones.
Abstract: The influence of the hypothalamus on the development of the anterior pituitary cells was studied in normal and anencephalic human fetuses. An immunocytological method was applied to study the quantitative evolution of the size of the cells during gestation. The somatotropic and corticotropic cells appeared at the end of the 2nd month of gestation. After the 3rd month of gestation their normal development required the presence of brain. The results suggest that hypothalamic factors are needed for the normal development of cells containing these pituitary hormones.
54 citations
TL;DR: The conclusion that accumulation and retention of pineal NREC are under partial dependence upon sympathetic nerves is supported, and estradiol administration brought about increases of complex levels.
Abstract: Pineal nuclear receptor estradiol complex determined by the 3H-estradiol exchange assay exhibited a kd = 0.42 nisi. Its concentration was maximal at proestrus and after administe
TL;DR: The case for multiple releasers of ACTH is reexamines and a search for the unique ACTH-releasing hormone is searched for.
Abstract: Early in the history of studies on the release of ACTH by stress there were indications that ACTH might be released by multiple factors. But the neurohumoral theory, as formulated by G. W. Harris, suggested that every hypophysial hormone had its unique hypothalamic controlling agent and a search for the unique ACTH-releasing hormone went on for about 20 years. This review reexamines the case for multiple releasers of ACTH.
TL;DR: It is concluded that the MBH contains dopamine-free PIF, which, as already shown for several other neurohormones, is exclusively distributed in nerve-endings.
Abstract: In order to check the hypothesis of an identity of dopamine (DA) and prolactin inhibiting activity (PIF), their subcellular distribution was studied in the mediobasal hypothalamus (MBH) and the striatum, which served as a control structure. PIF was tested both in vivo and on pituitary incubates. Fractions were also assayed after adsorption of their catecholamine content on alumina, as well as in presence of haloperidol or alpha-flupentixol, potent DA receptor inhibitors. In the MBH, PIF was evenly distributed in the 17,000 g supernatant (S2) and in the crude mitochondrial fraction (P2) which contains synaptosomes. PIF activity was completely removed by alumina adsorption of S2, but not of P2 in spite of an over 99.9% elimination of DA. In contrast, striatal PIF activity was detected only in P2, and disappeared completely upon alumina adsorption, thus indicating that, in this structure, it is entirely due to DA. Addition of haloperidol (10--5M) or alpha-flupentixol (10--6M) reduced PIF activity of crude MBH homogenates, but no longer affected it after alumina adsorption. Quantitative studies suggest that only half of the total MBH PIF activity is accounted for by DA. It is concluded that the MBH contains dopamine-free PIF, which, as already shown for several other neurohormones, is exclusively distributed in nerve-endings.
TL;DR: Administration of thyrotropin releasing hormone twice daily for 10 days produced a dose- and time-dependent rise in spontaneous locomotor activity of young rats and a significant increase in t.I.p.
Abstract: I.p. administration of thyrotropin releasing hormone (TRH) twice daily for 10 days produced a dose- and time-dependent rise in spontaneous locomotor activity of young rats. A significant increase in t
TL;DR: Pharmacological and neurosurgical approaches were used to determine whether central serotoninergic systems are essential to the diurnal fluctuation of plasma corticosterone (B) and the enhanced secretivity of serotonin (A) in mice.
Abstract: Pharmacological and neurosurgical approaches were used to determine whether central serotoninergic systems are essential to the diurnal fluctuation of plasma corticosterone (B) and the enhanced secret
TL;DR: Results suggest a synchronizing and generating action of feeding for the circadian adrenocortical rhythm, synchronizing with the feeding periods, was promptly recovered under food restriction.
Abstract: Influences of food restriction on the circadian adrenocortical rhythm were studied in blinded and unblinded rats under constant light (LL). Blinded rats, which were allowed to access to food
TL;DR: Six patients with idiopathic isolated gonadotropin deficiency were treated with 100 microgram LH-RH s.c. 3 times daily, leading to subnormal increases of serum gonadotropic levels, and promoting puberty from stage I to stage II-III of TANNER, but long-term therapy with the analogue did not improve hypogonadism.
Abstract: Six patients with idiopathic isolated gonadotropin deficiency (IGD) were treated with 100 µg LH-RH s.c. 3 times daily, leading to subnormal increases of serum gonadotropin (Gn) and testosterone (T) le
TL;DR: The results suggest the presence of VP receptor sites in the anterior pituitary (AP) which are probably different from the receptor sites of the hypothalamic corticotropin releasing factor (CRF).
Abstract: The in vitro corticotropic releasing effects of vasopressin (VP) and hypothalamic median eminence (HME) extract were compared as a function of their concentration and preincubation
TL;DR: Results indicate that photoperiod, which is well known to exert major effects on the reproductive system of the golden hamster, does not do so by directly altering the responsiveness of the pituitary gland to hypothalamic Gn-releasing factor.
Abstract: The effect of various doses of LRF on pituitary LH and FSH release was examined in castrated adult male hamsters with different photoperiodic histories. Gonadotropin (Gn) release in response to LRF wa
TL;DR: The results indicate that the response of the pituitary to TRH as regards the secretion of TSH is mainly regulated by norepinephrinergic alpha-receptors.
Abstract: The effect of chlorpromazine (CPZ), thioridazine (TR), L-dopa, fusaric acid (FA), pimozide (PZ) and propranolol (P) on the i.v. thyrotropin-releasing hormone (TRH) stimulation test was studied in 75 s
TL;DR: Data indicate that in the infant rat the 5- HTP-induced Prl release is mediated via the brain 5-HT system and that a nonspecific activation of the catecholaminergic system is responsible for the GH response to the drug.
Abstract: In 10 day-old female and male rats, administration of 5-hydroxytryptophan (5-HTP) induced a prompt elevation in plasma prolactin (Prl) and growth hormone (GH) levels. Pretreatment with 2 serotonin (5-HT) receptor blockers, methysergide (Meth) and metergoline (MCE), markedly reduced the 5-HTP-induced Prl rise but failed to alter the GH response to 5-HTP. Administration of 2 selective inhibitors of presynaptic 5-HT reuptake, 3-(p-trifluoromethylphenoxy)-N-methyl-3-phenyl-propylamine and chlorimipramine (CIM), potentiated the 5-HTP-stimulated Prl rise but significantly reduced the 5-HTP-induced GH release. Blockade of dopaminergic or alpha-adrenergic receptors by pretreatment with pimozide (Pim) or phentolamine (Phent), respectively, or central sympathectomy by intraventricularly (i.vt.) injected 6-hydroxydopamine (6-OHDA) were capable of reducing the 5-HTP-induced GH release without affecting the 5-HTP-induced Prl rise. These data indicate that in the infant rat the 5-HTP-induced Prl release is mediated via the brain 5-HT system and that a nonspecific activation of the catecholaminergic system is responsible for the GH response to the drug.
TL;DR: Data suggest that the septum or adjacent fibers of passage inhibit growth in adult hamsters, and SEP lesions significantly increased somatic growth rate, food consumption and serum concentration of growth hormone (GH) and insulin.
Abstract: Somatic, endocrine and behavioral correlates of growth were measured in intact and hypophysectomized adult hamsters with or without electrolytic damage to the rostral septal area. Septal (SEP) lesions significantly increased somatic growth rate, food consumption and serum concentration of growth hormone (GH) and insulin. Pituitary GH content and concentration were reduced in lesioned hamsters. None of these changes were found in hypophysectomized hamsters with SEP lesions. SEP lesions did not affect the percentage of body fat. These data suggest that the septum or adjacent fibers of passage inhibit growth in adult hamsters.
TL;DR: It is suggested that melatonin is a potential contributor to the physiologic regulation of adrenal steroidogenesis and an aqueous extract of bovine pineal glands on adrenal function were studied.
Abstract: The effects of melatonin and an aqueous extract of bovine pineal glands on adrenal function were studied in pinealectomized, ovariectomized and hypophysectomized rats. Melatonin (50 µg i.p., twice daily for 1 week) stimulates adrenal 5α-reductase activity in intact animals and after ovariectomy. A corresponding enhancement in the secretion of the principal 5α-reduced metabolites of corticosterone (B), dihydrocorticosterone (DHB) and tetrahydrocorticosterone (THB), occurs in vivo. As a result, proportional output of B declines. In contrast, an aqueous pineal extract (360 mg bovine pineal tissue/day for 1 week) fails to alter reductase activity or to produce the secretory changes associated with increased reductive metabolism of B. Melatonin also stimulates adrenal reductase activity in hypophysectomized rats. The results suggest that melatonin is a potential contributor to the physiologic regulation of adrenal steroidogenesis.
TL;DR: Bilateral anterior cervical sympathetic ganglionectomy in castrated male goats had no effect upon the subsequent seasonal variation in the concentration of prolactin (Prl) in plasma when surgery was performed in summer, but after ganglionsectomy in winter, the subsequent rise in Prl concentration associated with season was accelerated.
Abstract: Bilateral anterior cervical sympathetic ganglionectomy in castrated male goats had no effect upon the subsequent seasonal variation in the concentration of prolactin (Prl) in plasma when surgery was performed in summer. After ganglionectomy in winter, however, the subsequent rise in Prl concentration associated with season was accelerated.
TL;DR: It is suggested that the Amyg may be involved in the neural triggering of AVP release from the neurohypophysis.
Abstract: To evaluate a possible role of the amygdala (Amyg) in the neural control of arginine vasopressin (AVP) release, adult female monkeys (Macaca mulatto) with electrodes chronically implanted in the Amyg, hypothalamus and pituitary gland were given 5% dextrose and water infusions and were stimulated electrically at these sites. Immediately before and after, and at 5, 10, 15 and 30 min intervals following electrical stimulation, blood samples were withdrawn from unanesthetized monkeys, through implanted cardiac cannulae, for radioimmunoassay (RIA) of plasma AVP and for plasma osmolality determination. In the Amyg-stimulated monkeys, plasma AVP rose rapidly to peak values at the end of stimulation followed by an abrupt post-stimulation fall to control levels in 30 min. A small yet significant rise in plasma osmolality was also observed. Electrical stimulation of the hypothalamus and the pituitary gland yielded a temporal pattern of plasma AVP
TL;DR: It is concluded that PI ACTH and MSH secretion are altered with feedback-induced alterations in gonadotropin secretion and with neurotropic stressors.
Abstract: Pars intermedia (PI) ACTH and melanocyte-stimulating hormone (MSH) content and pars distalis (PD) ACTH concentration were measured following 3 experimentally induced ‘perturbations’. The feedback-indu
TL;DR: It appears that severe chronic stress in hemi-thyroidectomization-adrenalectomized-ad RenalectOMized-ovariectomizer animals further increases the ACTH response but antagonizes the increased secretion of the other pituitary hormones.
Abstract: Morphologic and hormonal changes, induced by combined ablation of a thyroid lobe, one adrenal and one ovary, were studied over a 15-day period in rats, some of whom were subjected to 8 h of daily immobilization. The compensatory hypertrophy (CH) of the contralateral glands in non-stressed animals was associated with a significant increase in the plasma levels of LH (from the 1st to the 10th day), prolactin (PRL, from the 3rd to the 6th day), FSH (on the 3rd day) and corticosterone (from the 6th to the 15th day), whereas GH titers were not altered. Immobilization for 1, 3, 6, 10 or 15 days inhibited the b.w. gain, induced involution of the thymus, enhanced compensatory enlargement of the adrenal, and blocked the CH of the ovary and, to a lesser degree, of the thyroid. This chronic stressor produced a marked rise in plasma corticosterone, antagonized the surge of PRL, FSH and LH, and decreased the plasma levels of GH. On the basis of these morphological and hormonal variations, it appears that severe chronic stress in hemi-thyroidectomized-adrenalectomized-ovariectomized animals further increases the ACTH response but antagonizes the increased secretion of the other pituitary hormones.
TL;DR: The dysfunction of gonadotropin (Gn) secretion in senile female rats seems to occur earlier than aging of the system for behavioral estrus, which results in decreased lordosis response among senile rats.
Abstract: The lordosis response of 27 ovariectomized senile female rats (20 to 32 months old) primed with either estrogen-progestrone (E/P) or estrogen (E) alone was studied and compared with that of ovariectom
TL;DR: Data are not compatible with the hypothesis of a monotonic relationship between SWS and GH secretion, and a significant decline in SWS was found with increasing chronological age, while the REM parameter did not show any significant changes across age categories.
Abstract: Ten patients with isolated growth hormone (GH) deficiency and 13 age-matched normal controls were studied. All patients were below the 3rd percentile in height and weight. All but 1 subject were studied for 3 or 4 consecutive nights in the sleep laboratory which included monitoring of the EEG, EOG, EMG, and EKG. GH samples were taken during sleep in 6 of the 10 patients. There were no significant differences in the slow-wave sleep (SWS) parameter between the 2 groups, nor was there any difference when all growth hormone patients were compared to controls. The age group comparisons for the percent of rapid eye movement (REM) sleep parameter revealed a significant difference between GH and controls for the youngest group only (p less than 0.05). Similar results were obtained when the GH subjects were grouped according to bone age. A significant decline in SWS was found with increasing chronological age (p less than 0.02), while the REM parameter did not show any significant changes across age categories. None of the patients showed a sleep-related peak in GH secretion. These data are not compatible with the hypothesis of a monotonic relationship between SWS and GH secretion.
TL;DR: Experiments were conducted in rats and cats in which cortisol and corticosterone were applied by iontophoresis and pressure microinjection while recording from single identified pyramidal cells in the dorsal hippocampus, using multi-barrelled microelectrodes and none of the more than 500 cells tested responded with a significant change in firing rate.
Abstract: In view of the possible role of the hippocampus in the neuroendocrine regulation of ACTH secretion, experiments were conducted in rats and cats in which cortisol (C) and corticosterone (CS) were applied by iontophoresis and pressure microinjection while recording from single identified pyramidal cells in the dorsal hippocampus, using multi-barrelled microelectrodes. None of the more than 500 cells tested responded with a significant change in firing rate. The possible relation of these findings to neuroendocrine regulation of ACTH secretion is discussed.