Showing papers on "Hypothalamus published in 1968"
TL;DR: This study attempted to determine the degree to which circulating, radioactive corticosterone enters and remains in the brain, because the limbic system of the brain is implicated in the control of the secretion of ACTH and in the affective behavioural responses.
Abstract: CORTICOSTERONE is one of the principal steroids secreted by the rat adrenal gland1–3 and it is well established that various noxious psychological and physiological stimuli promote the release of this substance into the blood. Because we are interested in the action of such corti-costeroids on biochemical processes in the brain, we attempted to determine the degree to which circulating, radioactive corticosterone enters and remains in the brain. Furthermore, because the limbic system of the brain is implicated in the control of the secretion of ACTH4–6 and in the affective behavioural responses7–9, we were particularly interested to see whether structures in the limbic system retain corticosterone in a higher concentration than other areas of the brain. Published work on the uptake of the oestradiol by the brain10–13 indicates that the hypothalamus retains that hormone.
688 citations
TL;DR: In all brains, the preoptic area, prepiriform cortex, olfactory tubercle, and septum had particularly high, long-lasting uptake of both hormones.
Abstract: Radioactivity was found in cell bodies of neurons and glial cells throughout brains of male and female rats that had been injected with either testosterone-H3 or estradiol-H3. Uptake by limbic and hypothalamic structures was higher and longer lasting than that in nonlimbic structures. In all brains, the preoptic area, prepiriform cortex, olfactory tubercle, and septum had particularly high, long-lasting uptake of both hormones.
251 citations
TL;DR: The presence of specific hormones in excess of ontogenetically inappropriate times during development may compromise the capability of certain adaptive or survival value mechanisms at later stages of the life cycle, as well as provide for the later full expression of these adaptive mechanisms.
213 citations
TL;DR: The distribution of tryptophan hydroxylase in the cat brain was investigated and found to parallel roughly the distribution of serotonin.
Abstract: — The distribution of tryptophan hydroxylase in the cat brain was investigated and found to parallel roughly the distribution of serotonin. The most active areas are the caudate nucleus, septal area, anterior perforating substance, hypothalamus, amygdala and various areas of the midbrain.
95 citations
TL;DR: It is concluded that although sex drive can be influenced by various regions in the brain, primarily structures in the limbic system, complete elimination of copulatory behavior has only been achieved by destruction of medial structures in preoptic and anterior hypothalamic areas.
Abstract: Following bilateral destruction in the medial region of the preoptic-anterior hypothalamus of male rats copulation was eliminated completely in 5 and drastically reduced in 3 animals. Unilateral destruction of the same region did not affect the level of copulatory drive. Effects of bilateral lesions in the lateral zone of the preoptic-anterior hypothalamus could not be tested adequately because of poor survival of the subjects. The discussion notes that although sex drive can be influenced by various regions in the brain, primarily structures in the limbic system, complete elimination of copulatory behavior has only been achieved by destruction of medial structures in preoptic and anterior hypothalamic areas. Furthermore, only in this general region will hormone implantation bring about a return of copulatory behavior in the castrate rat.
87 citations
TL;DR: The distribution of monoamines in the hypothalamus of the Japanese quail has been studied using a histochemical fluorescence technique and it is found that catecholamine nerve fibres are localised in the nucleus tuberis and nucleus hypothalamicus posterior medialis and linked by fluorescent tracts running in the stratum cellulare internum.
Abstract: The distribution of monoamines in the hypothalamus of the Japanese quail (Coturnix coturnix japonica) has been studied using a histochemical fluorescence technique. In the posterior hypothalamus catecholamine-containing nerve fibres are localised in the nucleus tuberis and nucleus hypothalamicus posterior medialis and are linked by fluorescent tracts running in the stratum cellulare internum. Further tracts may be traced from the nucleus tuberis around the base of the third ventricle to the sub-ependymal layer of the median eminence, where they then appear to pass through the hypothalamo-hypophysial neurosecretory tract to terminate in the palisade zone on the portal vascular bed. The innervation of the palisade layer by catecholamines is sparse. The fluorescent terminals are spread evenly throughout both the anterior and posterior divisions of the median eminence. There is no monoamine innervation of the pars nervosa. The paraventricular organ has both 5-hydroxytryptamine- and catecholamine-containing cell bodies and axons may be traced into the region of the nucleus hypothalamicus posterior medialis. In the anterior hypothalamus the neurosecretory paraventricular nucleus contains many catecholamine nerve fibres and terminals. These are linked by fibre tracts to the nucleus basalis and to the nucleus hypothalamicus posterior medialis. The supraoptic nucleus is less well innervated although a dense accumulation of fibres lies in the preoptic recess. The latter is thought to give rise to long axons which pass in association with the neurosecretory tract to end in the nucleus tuberis.
80 citations
72 citations
TL;DR: The ultrastructural changes observed in the arcuate complex, after castration, are discussed in relation to the current knowledge on the histophysiology of this region of the hypothalamus and specially on the probable regulatory effect of monoamines on the secretion of gonadotrophins.
Abstract: SummaryThe arcuate complex, comprising the nucleus and the outer zone of the median eminence, was studied under the electron microscope in control and castrated rats of both sexes. One month after castration the arcuate neurons show signs of hyperactivity characterized by dilated cisternae of the endoplasmic reticulum, a large nucleolus, situated near the nuclear envelope and fewer granulated vesicles. The surrounding neuropile shows an increase in the number of granulated vesicles above the control level. Six months after castration the changes already described are more accentuated. In the outer zone of the median eminence the axons and terminals show a considerable increase in the number of granulated vesicles which is of the order of 50 per cent above the control. A correlation between the granulated vesicles and the high content in dopamine of the arcuate complex is postulated. The ultrastructural changes observed in the arcuate complex, after castration, are discussed in relation to the current knowledge on the histophysiology of this region of the hypothalamus and specially on the probable regulatory effect of monoamines on the secretion of gonadotrophins.
68 citations
TL;DR: The ultrastructural changes observed in the neurosecretory nuclei after castration are discussed in relation to those previously described in the Neurohypophysis under the same experimental conditions.
Abstract: The neurosecretory hypothalamic nuclei and the inner zone of the median eminence of castrated rats were studied under the electron microscope. After one month of castration all the neurosecretory neurons of both nuclei show signs of hyperactivity characterized by dilated cisternae of the endoplasmic reticulum containing a macromolecular filamentous material and an increase in the number of ribosomes. After six months of castration, some neurosecretory neurons show an increased number of neurotubules and larger lysosomes than in the controls. Other neurons show a very significant hypertrophy of the endoplasmic reticulum, with large amounts of intracisternal filamentous material. These cells have few neurosecretory granules and in the adjacent synapses the number of granulated vesicles is increased. In the supraoptic nucleus there are two kinds of neurosecretory axons: the clear ones, which are similar to those that appear in control animals and the dark ones, which have smaller elementary granules. In the inner zone of the median eminence the axons show an increase in the number of neurosecretory granules with respect to the controls. After supplementary administration of sexual hormones, all the modifications produced by castration disappear. The ultrastructural changes observed in the neurosecretory nuclei after castration are discussed in relation to those previously described in the neurohypophysis under the same experimental conditions. A feedback regulatory action of sex hormones on hypothalamic neurosecretory neurons is postulated.
65 citations
63 citations
TL;DR: There appeared also to be no sexual or age differences in the ability of the implants to secrete gonadotropin, at least for the hypophyses of fetuses between 11 and 28 weeks of embryogenesis.
TL;DR: The results support the view that adrenergic mediators participate in the neurohumoral control of GH secretion as well as other physiological constituents of hypothalamic tissue, i.e., serotonin, norepinephrine and dopamine.
Abstract: Epinephrine (0.5 μg), norepinephrine (0.5 and 0.1 μg) and dopamine (0.5 and 0.1 μg) when injected into the lateral ventricle of the rat brain, induced a depletion of growth hormone (GH) pituitary content. Unlike adrenergic compounds, other physiological constituents of hypothalamic tissue, i.e., serotonin (0.5 μg), acetylcholine (0.5 μg), vasopressin (8 mU) and oxytocin (8 mU) did not show any GHreleasing activity when given by intraventricular route. The effect of epinephrine, norepinephrine and dopamine appeared to be unrelated to changes of blood glucose or body temperature. These results support the view that adrenergic mediators participate in the neurohumoral control of GH secretion. (Endocrinology 83: 893, 1968)
TL;DR: FSH-releasing action of rat hypothalamic extracts was assessed by an in vitro assay with male anterior pituitaries and there was an indication of an increase in total FSH with low doses of extract which was not maintained at higher doses.
Abstract: FSH-releasing action of rat hypothalamic extracts was assessed by an in vitro assay with male anterior pituitaries. The endpoint was the increase in FSH in the medium after a 6 hr period of incubation. FSH was assayed by the rat ovarian weight augmentation method. Doses of crude extract prepared from of a rat stalk-median eminence/pituitary produced a significant increase of FSH release into the media and a dose-response relationship was obtained. Similarly prepared extracts from cerebral cortex or muscle were inactive, as was vasopressin. When FSH concentration of pituitaries was added to that of the medium in order to determine the effect of stalk median eminence extract on total FSH, there was an indication of an increase in total FSH with low doses of extract which was not maintained at higher doses. Frozen sections were cut in 3 planes through the hypothalamus to determine the localization of the FSH-releasing factor. Activity was localized to the medial, basal, tuberal region, an area which included...
TL;DR: The thalamus of unanesthetized unrestrained cats was explored stereotaxically for sites which when electrically stimulated will either give rise to attack, facilitate attack elicited from the hypothalamus, or suppress such attack.
Abstract: The thalamus of unanesthetized unrestrained cats was explored stereotaxically for sites which when electrically stimulated will either give rise to attack, facilitate attack elicited from the hypothalamus, or suppress such attack. A quiet biting form of attack could be elicited from the medial portion of nucleus dorsalis medialis, the caudal portion of nucleus reuniens, the midline region of nucleus centralis medialis, and anterolateral portions of nucleus reticularis. Facilitation of hypothalamic attack also occurred with stimulation of these same sites. In addition, facilitation was observed from sites that did not give rise to attack. These include nucleus ventralis anterior, area subparafascicularis, and the paraventricular region medial to the nucleus parafascicularis. Suppression of attack was elicited by stimulation of sites which by themselves gave rise to retreat from discrete objects in the environment, or to "fear-like" responses. The areas whose excitation suppressed attack include anterolateral portion of the reticular nucleus, the region of the anterior thalamic radiations, the rostral portion of nucleus reuniens, nucleus interoanteromedialis, somewhat lateral portions of nucleus dorsalis medialis and posterior portions of centrum medianum. The responses seen by a number of previous investigators are also confirmed. Finally, the possible pathways mediating attack and its suppression are discussed.
TL;DR: Endocrine data indicate that in these unusual patients, normal or accelerated growth can occur when growth-hormone secretion is so low as to be only barely detectable by presently available technics.
Abstract: Nine patients had normal or superior rates of statural growth after the removal of tumors impinging upon the pituitary gland and hypothalamus (craniopharyngioma in eight and third-ventricle cyst in one). After operation hyperphagia and obesity, as well as deficiencies of vasopressin, thyroxine and cortisol, were observed. Four patients over 15 years of age remained sexually immature, with no measurable gonadotropin excretion. Immunoassay of plasma showed barely detectable growth hormone during fasting and after Stimulation by hypoglycemia in nine of the patients and after exercise in six. The patients were free of hypoglycemic symptoms, and fasting blood sugar levels were normal; the serum immunoreactive insulin levels were in the low-normal range, except in the presence of obesity. The endocrine data indicate that in these unusual patients, normal or accelerated growth can occur when growth-hormone secretion is so low as to be only barely detectable by presently available technics.
TL;DR: It is suggested that hormone receptors degenerate in long-term absence of estradiol, and that hormone retention curves may result from appearance of new receptor activity.
Abstract: A number of investigators have published data supporting the concept of specific binding sites (receptors of limited capacity) for estradiol in the uterus and vagina,1-8 pituitary,7-\" and hypothalamus.7' 8, 10, 12-14 This concept is based on the observations that in immature or in adult ovariectomized female rats, estradiol is preferentially accumulated and retained with little or no metabolic conversion in target tissues, and that antiestrogenic drugs and nonradioactive estrogen compete with labeled estradiol for the receptors. It is thought that these estrogen receptors may be involved in the primary action of estrogen in target tissues. Results presented here lead to a new interpretation of the time course and nature of estrogen-receptor binding. It is suggested that hormone receptors degenerate in long-term absence of estradiol, and that hormone retention curves may result from appearance of new receptor activity. Preliminary results have been reported in abstract form.16 Materials and Methods.-The animals employed were adult female Sprague-Dawley rats weighing 200-250 gm. For retention studies, they were used either 11 days or 4 weeks after ovariectomy. Henceforth these two groups of female rats will be referred to as 11-day or 4-week castrates. Estrous cycles of intact female rats were determined by examining for vaginal cornification. These animals were used either on the morning of diestrus one (a time when estrogen titre is low) or on the night of proestrus (a time when estrogen titre is high). Protocol: Rats were injected with 1 Ac 'H-estradiol (42.4 c/mmole) intravenously and were killed by ether at various time intervals after injection. An early set of data showed no difference in results when animals were killed by decapitation. At autopsy, after blood samples were obtained, the animals were perfused through the left ventricle with 500 mil of 0.9%O saline in order to eliminate plasma estrogen contamination in the various tissue samples. The pituitary and samples of uterus, muscle, liver, and cerebrum were removed. The entire hypothalamus was cut out as a block, limited anteriorly by a cut through the center of the optic chiasm, laterally by the hypothalamic fissures, and posteriorly by the anterior border of the mammillary bodies. The depth from the basal surface of the hypothalamus was 2-3 mm. Protein inhibition studies were carried out by injecting 10 mg cycloheximidel7 intraperitoneally 15 min prior to injection of labeled hormone. Assay: Tissues were dried in vacuo at 60°C for 24 hr and allowed to cool before being weighed. Tissues were homogenized in 5 ml tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate (Tris-EDTA) buffer in a glass homogenizer and extracted three times with 5 ml ethyl acetate; the combined extracts were dried in scintillation vials. Radioactivity was measured by means of a scintillation counter, correction for quenching being made by use of an internal standard. Activity above background was expressed on the basis of 100 mg tissue dry weight. Depression of protein synthesis was determined by the method of Korner.17 Protein determination was carried out by the method of Lowry et al.'8 Chemicals: 3H-estradiol was obtained from New England Nuclear Corporation and cycloheximide from Sigma Chemical Corporation, St. Louis, Missouri.
TL;DR: The effects of intracarotid injection of hypothalamic extracts on the ultrastructure of pituitary growth hormone (GH)-producing cells are reported and the relevance of these morphological findings to the understanding of the action of hypothalamus extract on the GH cells is discussed.
Abstract: The effects of intracarotid injection of hypothalamic extracts on the ultrastructure of pituitary growth hormone (GH)-producing cells are reported. Male rats were killed 15, 30 and 90 min after injection of hypothalamic extract. After 15 min the secretory granule content of pituitary GH cells was similar to that of nonstimulated glands. However, the release of granules into the perivascular spaces was greatly increased. The releasing phenomenon was still present 30 min after the injection; at this time a prominence of the endoplasmic reticulum as well as of the Golgi apparatus was also noticed. At 90 min the release of secretory granules was reduced to a normal rate; numerous lytic bodies were present. The number of secretory granules seemed to be within a normal range. The relevance of these morphological findings to the understanding of the action of hypothalamic extracts on the GH cells is discussed. (Endocrinology 83: 1278, 1968)
TL;DR: With the dosage used in this study, 2-deoxy-d-glucose did not produce any generalized changes in blood sugar or an arterior-venous glucose difference in the cat and the significance of the specific response of hypothalamic feeding centers to glucopenia is discussed.
TL;DR: The data provide additional evidence for androgen-sensitive mechanisms in anterior hypothalamus and suggest that neural cells mediating mating behavior can be primed or triggered by androgen very early in development.
TL;DR: Pathways which might connect the effective mesencephalic area with the thalamic gustatory nucleus and the lateral hypothalamic feeding area are described and resulted in significant impairments of sodium intake regulation.
TL;DR: Radioautographic techniques were used to study the effects of osmotic stimuli on the rate of proliferation of neuroglia cells in the hypothalamus of the rat and dehydration appears to act as a stimulus to glial proliferation in the supraoptic nucleus and posterior pituitary.
TL;DR: Five polyamine substances already known to occur naturally in mammalian tissues have been isolated from porcine hypothalamic extracts and it is shown that these substances account for most of the FSH-depleting activity of the crude extracts.
Abstract: Five polyamine substances already known to occur naturally in mammalian tissues have been isolated from porcine hypothalamic extracts. Taken together, these substances account for most of the FSH-depleting activity of the crude extracts. Of the polyamines isolated, histamine is present in the highest amount. However, in the assay method used (decrease of pituitary FSH levels in intact and in castrated testosterone-treated male rats) histamine is active only at μg levels; whereas putrescine, which occurs in smaller amounts, is active down to levels of a few ng. Spermidine, spermine and lysine, which have also been identified, are active at intermediate dose levels. The exact roles of the 5 amines in the turnover of pituitary FSH remain to be elucidated. (Endocrinology 82: 742, 1968)
TL;DR: Observations indicate that the stimulatory effect of the 3 hormones on pituitary prolactin secretion is mediated through the hypothalamus.
Abstract: SummaryThe effects of P, TP, and CA on hypothalamic PIF content, pituitary prolactin concentration, and mammary development were studied in mature ovariectomized rats. Each of the 3 steroids significantly decreased hypothalamic PIF content, increased pituitary prolactin concentration and, induced mammary growth. The TP and CA also elicited mammary secretion. These observations indicate that the stimulatory effect of the 3 hormones on pituitary prolactin secretion is mediated through the hypothalamus.
Journal Article•
TL;DR: The role of thyroid hormone as a feed‐back at the hypothalamic level in the control of thyrotrophin (TSH) secretion and release has been investigated by estimating the plasma and pituitary TSH levels following intrahypophysial andIntrahypothalamic thyroid autotransplants.
Abstract: 1. The role of thyroid hormone as a feed-back at the hypothalamic level in the control of thyrotrophin (TSH) secretion and release has been investigated by estimating the plasma and pituitary TSH levels following intrahypophysial and intrahypothalamic thyroid autotransplants.
2. Thyroidectomized rats bearing thyroid autotransplants in the pituitary had a significantly lower (P < 0·001) plasma TSH than that of controls at 26° C but not at 4° C.
3. Thyroidectomized rats bearing thyroid autotransplants in the supraoptic area showed a significantly lower (P < 0·001) level of plasma TSH and higher pituitary TSH at 4° C but not at 26° C.
4. Study with both unilaterally and bilaterally thyroidectomized rats bearing thyroid autotransplants either in the pituitary or in the hypothalamus revealed that thyroxine feed-back operates at pituitary level in normal situations (26° C) and there exists a feed-back through higher centres, specifically the TSR secreting area of the hypothalamus, in situations demanding higher thyroid function, as in cold exposure.