Showing papers on "Hypothalamus published in 1971"
TL;DR: The LH-RH preparation isolated has FSH-releasing hormone (FSH-RH) activity, which appears to be intrinsic to LH- RH, and appears to represent the hypothalamic hormone which controls the secretion of both LH and FSH from the pituitary.
585 citations
TL;DR: A quantitative evaluation of the relative distribution of synapses on dendritic shafts and spines serves to differentiate the neuropil of the preoptic area from that of the ventromedial hypothalamic nucleus and shows that the neurosensory area is sexually dimorphic.
Abstract: A quantitative evaluation of the relative distribution of synapses on dendritic shafts and spines serves to differentiate the neuropil of the preoptic area from that of the ventromedial hypothalamic nucleus; it also shows that the neuropil of the preoptic area is sexually dimorphic.
301 citations
TL;DR: Clinical studies suggest LH-RH may be useful in the treatment of fertility and as a diagnostic aid in distinguishing between pituitary and hypothalamic disorders.
177 citations
TL;DR: Dopamine, epinephrine, or norepinephrine, perfused into the anterior pituitary for 30 min via a hypophysial portal vein, had no effect on prolactin release and dopamine greater than 2.5 jug caused less inhibition of release.
Abstract: In rats, the median eminence, pituitary stalk and anterior pituitary were exposed parapharyngeally and catecholamines were injected into the third ventricle or infused into a stalk portal vessel, peduncular artery, or a tuberalis ramus of an infundibular artery. Ten min after 1.25 μg dopamine hydrochloride was injected into the third ventricle, the plasma prolactin concentration was 70% of the preinjection value; 47% at 20 min; 42% at 30 min; 57% at 60 min; 69% at 90 min; and 93% at 120 min. Similar responses occurred following the administration of 2.5 μg dopamine. Quantities of dopamine greater than 2.5 jug caused less inhibition of release, however. Intraventricular injection of 2.5 or 5 μg of epinephrine or norepinephrine bitartrate did not affect prolactin release although 100 μg did. Dopamine, epinephrine, or norepinephrine, perfused into the anterior pituitary for 30 min via a hypophysial portal vein, had no effect on prolactin release. Dopamine, infused into the stalk-median eminence complex via t...
177 citations
TL;DR: Evidence is reviewed for the concept that prolactin is one of the essential hormones for maternal behavior in the rabbit, rat and mouse and retrieval, crouching and licking of pups is obtained following treatment with estradiol, progesterone and Prolactin.
162 citations
TL;DR: Nonpuerperal lactation may be the result of pituitary tumors or functional pituitaries disorders, and Elevations of serum prolactin measured by radioimmunoassay were found in three patients with nonpuer Peruvian lactation.
Abstract: Nonpuerperal lactation may be the result of pituitary tumors or functional pituitary disorders. Elevations of serum prolactin measured by radioimmunoassay were found in three patients with pituitary tumors and in one of two patients with functional pituitary disorders. Ingestion of 0.5 g of levodopa (L-dopa) produced a profound fall in serum prolactin in all patients by 90 minutes; thereafter, levels tended to rise toward base-line values. Sustained suppression of serum prolactin levels could not be achieved when L-dopa was given four times daily, although the suppressive effect of a single dose was always demonstrable. More prolonged treatment of one patient did not decrease lactation or lower basal prolactin levels. Because L-dopa probably exerts its effects on the pituitary gland via the hypothalamus, these studies suggest that pituitary tumors associated with lactation may not be autonomous.
151 citations
TL;DR: Small stimulating lesions in the region of medial preoptic area (MPOA) consistently stimulated the release of LH within 1 hr, which was associated with ovulation even though FSH release was unaltered, and when electrode placements were localized in mo...
Abstract: The possibility of the existence of specific loci controlling the release of gonadotropins and prolactin was explored by studying the effects of electrochemical stimulation of various regions in and adjacent to the hypothalamus on plasma gonadotropins and prolactin. Sprague- Dawley rats with 4-day estrous cycles had elevated plasma levels of LH, FSH and prolactin during the afternoon of proestrus. The administration of Nembutal at 1:30 PM on the day of proestrus inhibited this surge. Various regions of the hypothalamus were electrochemically stimulated using stainless steel bipolar concentric electrodes with direct current of 100 μA for 60 sec. Plasma levels of LH, FSH and prolactin at different intervals following stimulation were estimated by radioimmunoassay. Small stimulating lesions in the region of medial preoptic area (MPOA) consistently stimulated the release of LH within 1 hr, which was associated with ovulation even though FSH release was unaltered. When electrode placements were localized in mo...
100 citations
TL;DR: Daily injections of 400 jug ergocornine/100 g bw for 20 days or a single implantation of approximately 200 μg in the median eminence suppressed all fluctuations in serum Prolactin values during the estrous cycle and depressed pituitary prolactin and LH levels in rats.
Abstract: Daily injections of 400 jug ergocornine/100 g bw for 20 days or a single implantation of approximately 200 μg in the median eminence suppressed all fluctuations in serum prolactin values during the estrous cycle and depressed pituitary prolactin and LH levels in rats. Regularity of estrous cycles was not disturbed as determined by daily vaginal smears. An injection of 5, 50, or 200 μg of ergocornine/100 g bw in the early afternoon of proestrus completely prevented the marked rise in serum prolactin which normally occurs on the late afternoon of proestrus. Only doses of 50 or 200 μg of ergocornine significantly depressed the normal serum LH peak on the late afternoon of proestrus. All animals ovulated during the following night, suggesting that less LH is required to induce ovulation than is normally released by the pituitary. Male pituitary halves incubated in vitro with hypothalamic extract from ergocornine-treated animals released less prolactin and LH than the corresponding pituitary halves incubated w...
98 citations
TL;DR: Examination of extracellular recordings provides evidence in support of the hypothesis that ADH release is related to an increase in the discharge rate of supraoptic neurosecretory cells.
90 citations
88 citations
TL;DR: Norepinephrine synthesis in posterior hypothalamus and serotonin synthesis in both regions of the hypothalamus were similar in the two groups, and it was demonstrated that norepine cortisol synthesis was greater in the anterior hypothalamus of ovariectomized rats than in the posterior hypothalamic region of ovarian rats treated with 17β-estradiol and progesterone.
Abstract: A method is presented for determining the synthesis rate of norepinephrine and serotonin in anterior and posterior hypothalamus of rat from the changes of specific radioactivity of these amines and their respective precursor amino acids after an intraventricular injection of the radioactive amino acids. With our procedure we demonstrated that norepinephrine synthesis was greater in the anterior hypothalamus of ovariectomized rats than in the anterior hypothalamus of ovariectomized rats treated with 17β-estradiol and progesterone. Norepinephrine synthesis in posterior hypothalamus and serotonin synthesis in both regions of the hypothalamus were similar in the two groups. (Endocrinology 89: 1345, 1971)
TL;DR: It is conceptualized that the steroid hormone neurons are hypophysiotropic neurons, being involved in the neurosecretion of releasing factors, and that they represent sought for hormone “feedback” areas in the brain.
Abstract: SYNOPSIS. Autoradiographic techniques are reviewed which have been recommended. for the localization of diffusible substances, such as steroid hormones. Advancement in techniques, including low temperature tissue sectioning, section freeze-drying, and dry-mounting of sections, led to the development of the dry-mount autoradiographic technique. This progress in technique has enabled the cellular and subcellular topotgraphic localization of steroid hormones in peripheral and central target tissues, including the identification of hormone target cells in the pituitary and mapping of hormone neurons in the brain. In the pituitary, tritiated estrogen, androgen, and glucocorticoid are concentrated and retained in nuclei of certain anterior lobe cells. In the brain, estrogens, androgens, and glucocorticoids are attracted by and concentrated in nuclei of certain neurons located mainly within the phylogenetically old periventricular brain. In view of the widespread distribution of sex steroids in different brain areas, the generally held concept of a topographically confined single or dual “sex center” is challenged. While estrogen and androgen neurons in the hypothalamus, in the preoptic-septal-parolfactory region, and in the amygdala overlap, or are even identical in part, glucocorticoid neurons are more heavily concentrated in the gyrus dentatus, hyppocampus, indusium griseum, dorsal nuclei septi lateralis and medialis, as well as in the piriform cortex and portions of the amygdala. It is conceptualized that the steroid hormone neurons are hypophysiotropic neurons, being involved in the neurosecretion of releasing factors, and that they represent sought for hormone “feedback” areas in the brain. This challenges the generally held view of the “hypophysiotrophic area” in the hypothalamus as the anatomical site where releasing factors are produced.
TL;DR: It is suggested that the constant estrus observed in many old female rats is the result of a fundamental change in hypothalamic control of pituitary FSH, LH, and prolactin secretion.
Abstract: Hypothalamic and pituitary functions of 21-month-old rats in constant estrus were compared with those of 3-month-old cycling rats on the day of estrus. FSH-RF in the hypothalamus and pituitary FSH were significantly higher in the old than in the young rats. Pituitary LH was significantly lower in the old than in the young rats. Hypothalamic PIF was similar in both groups, but pituitary prolactin concentration was significantly greater in the old rats. The old constant-estrous rats showed well-developed ovarian follicles but no corpora lutea, increased uterine weight, hyperplastic mammary glands, and increased pituitary weight. It is suggested that the constant estrus observed in many old female rats is the result of a fundamental change in hypothalamic control of pituitary FSH, LH, and prolactin secretion.
TL;DR: Implantation of crystalline cortisol acetate in the medial basal hypothalamus (MBH), apart from inhibiting pituitary adrenal responses, had a profound suppressive effect on the reproductive system of mice.
Abstract: Implantation of crystalline cortisol acetate in the medial basal hypothalamus (MBH), apart from inhibiting pituitary adrenal responses, had a profound suppressive effect on the reproductive system of
TL;DR: The effects of interruption of the rostro-dorsal afferents to the medial hypothalamus coming from the amygdala and hippocampus upon spontaneous and induced ovulation in adult female rats was studied, supporting the proposed inhibitory role of the hippocampus.
Abstract: The effects of interruption of the rostro-dorsal afferents to the medial hypothalamus coming from the amygdala and hippocampus upon spontaneous and induced ovulation in adult female rats was studied. Transections of the limbic afferents through the stria terminalis (ST) and through the tractus cortico-hypothalamicus medialis (CHT) at the retrochiasmatic section (RCS) in which hypothalamic connections of the preoptic area were also interrupted or a similar transection of the pre-optic-roof section (PRS) on the morning of pro-estrus 24 hours before autopsy blocked spontaneous ovulation. In rats in which the ST was unilaterally severed ovulation was normal while bilateral interruption blocked ovulation. Normal ovulation followed interruption of CHT. Acute electrolytic lesions in areas of the brain outside of limbic areas did not affect spontaneous ovulation. Lesions of the medial amygdaloid nucleus blocked ovulation completely while lesions of the basolateral complex were less effective. Rats autopsied 30 or more days following ST section showed a diestrous smear for 10 to 15 days. All groups with long term lesions ovulated except those with RCS lesions. Thus some degree of functional reorganization occurred. Rats injected sc with 2 mg progesterone 2 or 3 hr following transection of the ST did not ovulate. Ovulation was elicited by electrochemical stimulation of the medial preoptic area in 8 out of 11 similarly operated rats. Ovulatory response induced by 2 mg progesterone on the third day of proestrus was significantly lower in operated animals (3 out of 11 ovulating) supporting the proposed inhibitory role of the hippocampus. Estrogen did not activate the hippocampal influence. Injection of picrotoxin known to block inhibitory synapses 1 mg/kg 45 and 90 minutes after progesterone treatment resulted in 6 out of 8 ovulating. In PRS animals progesterone induced ovulation in 6 out of 8 rats the following morning. Ovulation occurred after preoptic electrochemical stimulation in 7 out of 8 ST rats and in 4 out of 5 rats with PRS. After chronic interruption of the ST or PRS the increase in plasma LH 5 hr after progesterone injection following priming with gonadal steroids indicated a stimulatory effect of the amygdala. Rats with chronic transection of the CHT had higher concentrations of plasma LH (P < .05) than controls. The amygdala and hippocampus are part of a modulatory system regulating the function of the primary stimulatory structures represented by the preoptic-hypothalamic region.
TL;DR: The present study deals with the effect of vaginal stimulation with a glass rod on unit activity in the brain and the correlation of the activity of each area under certain hormonal conditions.
Abstract: The present study deals with the effect of vaginal stimulation (VS) with a glass rod on unit activity in the brain and the correlation of the activity of each area under certain hormonal conditions. The frequency characteristics of the neuronal discharges in the brain stem, limbic structures, and hypothalamus were recorded, using stereotaxically oriented steel micro-electrodes, in adult female rats under light urethane anesthesia. The following results were obtained: (1) The level of ‘spontaneous’ activity in the anterior hypothalamic, preoptic, and septal areas of estrogen-primed spayed rats was higher than that observed in ovariectomized, non-estrogen-primed rats. (2) Significant and discriminated responses induced by VS were observed only in the estrous state, that is, after estrogen priming in the case of the ovariectomized animals. (3) These responses were almost independent of the EEG activity level, and could be discriminated from the response to other peripheral stimuli such as pinching. (4) The firing rate of hypothalamic neurones, depending on their locations, increased or decreased during and only immediately after VS (‘phasic response’), by means of which the EEG after-reaction was induced. Reciprocal changes were observed between the periventricular arcuate nucleus (ARC) (facilitated) and ventromedial hypothalamus (VMH) (inhibited), and between the basal and medial parts of the anterior hypothalamic area (AHA) (inhibited) and the medial preoptic area (MPO) (facilitated). (5) Neurone activity in the ventromedial part of the midbrain reticular formation (MRF), in the dorsal hippocampus (DHPC), in the medial complex of the amygdala (AMYG) and lateral septum, was enhanced during and for some minutes after VS (‘tonic response’), with the appearance of the EEG after-reaction. (6) The MRF may play a significant role in discriminating vaginal impulses from other peripheral sensory afferents. Interrelations of the unit activity in the above portions of the brain in estrogen-primed rats were examined by electrical stimulation and the results were as follows: (1) The VMH and ARC nuclei were reciprocally interrelated, and there exists an inhibitory pathway between them that may subserve changes in functional activity. (2) Electrical stimulation of the MPO and the AHA decreased unit activity of the VMH and increased that in the ARC. (3) The cornu ammonis of DHPC and the medial complex of the AMYG had a reciprocal relationship with the hypothalamus. In other words, the DHPC increased AHA activity and decreased MPO activity, while the AMYG influenced these nuclei conversely. Similarly, the DHPC increased and the AMYG decreased unit discharge in the ARC, while they exerted a reverse influence on the VMH activity. It is therefore suggested that the DHPC mainly activates the AHA-ARC circuit and the medial AMYG activates the MPO-ARC circuit, while both the hippocampus and amygdala may participate in different functional reorganizations activated by responses to VS.
TL;DR: The lysosomal effects observed have served to delineate hitherto unsuspected changes in the cell cytoplasm in affected animals.
TL;DR: The persistent periodicity observed in the CRF activity in the absence of circulating corticosterone suggests that the dominating mechanism for the control of the circadian rhythm ofCRF activity is of neural origin, being independent of the negative feedback mechanism.
Abstract: Circadian periodicity of the hypothalamic content of corticotropin-releasing factor (CRF) was determined in normal and adrenalectomized male rats, using the intrapituitary micro-injection method. It was found that the CRF activity in the rat hypothalamus showed a definite circadian variation, having the peak value at 6 p.m. and the minimum at 8 a.m. under the lighting schedule used here (light between 6 a.m. and 7 p.m. followed by 11 h of darkness). A close temporal relationship with a definite phase shift was observed between the CRF activity and plasma corticosterone level. The finding thus supports the concept that the circadian rhythm of the pituitary-adrenal axis is a direct reflection of the rhythmicity of CRF activity in the median eminence. Furthermore, the persistent periodicity observed in the CRF activity in the absence of circulating corticosterone suggests that the dominating mechanism for the control of the circadian rhythm of CRF activity is of neural origin, being independent of the negative feedback mechanism.
TL;DR: It is suggested that the increase in hypothalamic catecholamines produced by these drugs results in increased hypothalamic PIF activity, and this in turn depresses prolactin release by the pituitary.
Abstract: SummaryA single intraperitoneal injection of L-dopa, the precursor of dopamine, into female rats significantly reduced serum prolactin concentration at 30 min, 1 hr, and 2 hr after injection compared to pretreatment levels or control rats not given this drug. A single injection of each of 3 monoamine oxidase inhibitors, pargyline, iproniazid or Lilly-15641, also significantly decreased serum prolactin below pretreatment values. Injection of L-dopa and pargyline together was more effective than either alone in lowering serum prolactin. Each of the above drugs is believed to reduce pituitary prolactin release because it increases catecholamine activity in the hypothalamus. By contrast, a single injection of methyldopa, which inhibits catecholamine synthesis, increased serum prolactin many fold over pretreatment levels. A single injection of d-amphetamine, a sympatheticomimetic drug, also greatly increased serum prolactin concentration.AddendumThe hypothalami of the rats treated with saline (controls), ipron...
TL;DR: It is concluded that these forms of injury had specific effects on the brain monoamines and changes were found in the concentration of this monoamine and in that of its metabolite, 5‐hydroxyindole acetic acid, in the brain stem.
Abstract: — The monoamine concentrations have been measured in four regions of the brain (hypothalamus, cortex, cerebellum and brain stem) in rats injured by either hind-limb ischaemia or scald. Both injuries produced a rapid fall in the noradrenaline concentration of the hypothalamus which recovered slowly if the injury was not fatal. This effect of injury was seen after pretreatment with a-methyl-p-tyrosine to inhibit noradrenaline synthesis, indicating an increased rate of utilization of noradrenaline after injury. These injuries did not affect the 5-hydroxytryptamine concentration in the hypothalamus, but changes were found in the concentration of this monoamine and in that of its metabolite, 5-hydroxyindole acetic acid, in the brain stem. It is concluded that these forms of injury had specific effects on the brain monoamines. The hypothalamic changes were not secondary to changes in core temperature or to hypotension or hypovolaemia and they are discussed in relation to the impairment of temperature regulation seen in the injured rat.
TL;DR: The observation that protein synthesis was also depressed in the pituitary gland by neonatal thyroidectomy, suggests that thyroid hormone might play a critical role in pituitsary metabolism during early postnatal life.
TL;DR: It is suggested that the brain contains receptors sensitive to circulating levels of FSH-RF and, possibly, of other releasing factors; it is also postulated that F SH-RF might directly regulate its own production, through what might be called an ‘ultrashort’ feedback effect.
Abstract: Subcutaneous administration of crude rat hypothalamic extracts containing FSH-RF and devoid of any FSH and sex steroid contamination gives rise to a considerable reduction of FSH- RF stores in the hypothalamus of castrated-hypophysectomized rats. It is suggested that the brain contains receptors sensitive to circulating levels of FSH-RF and, possibly, of other releasing factors; it is also postulated that FSH-RF might directly regulate its own production, through what might be called an ‘ultrashort’ feedback effect.
TL;DR: The findings suggest a short-loop feedback action of Prolactin on the brain but do not localize the pathways employed.
01 Jan 1971
TL;DR: The results are compatible with the assumption that the rise of blood pressure during stimulation of the nucleus posterior of the hypothalamus is mediated by adrenergic neurons of the brain.
Abstract: The third ventricle and the aqueduct of the anaesthetized cat were cannulated and the hypothalamus was superfused with artificial cerebrospinal fluid. Electrical stimulation of the nucleus posterior of the hypothalamus elicited a rise of the blood pressure of 58±3 mm Hg (n=20). Superfusion of the hypothalamus with artificial cerebrospinal fluid containing bretylium (5×10−3 M) caused a gradual and long lasting impairment of the rise of blood pressure due to stimulation of the nucleus posterior. Tetracaine (1×10−3 M) diminished the rise of blood pressure to about the same extent as did 5×10−3M of bretylium; the inhibitory action of tetracaine was completely reversed within 120 min. Pretreatment of cats with 6-hydroxydopamine, which was applied through a Collison cannula implanted into the lateral ventricle, evoked a decrease of the noradrenaline content of the hypothalamus and of the rest of the brain and an impairment of the rise of blood pressure during stimulation of the nucleus posterior (33±3 mm Hg;n=6). The blood pressure of the anaesthetized cats was not affected by pretreatment with 6-hydroxydopamine. Superfusion of the hypothalamus with desipramine (1×10−4M) enhanced the rise of blood pressure elicited by electrical stimulation. The results are compatible with the assumption that the rise of blood pressure during stimulation of the nucleus posterior of the hypothalamus is mediated by adrenergic neurons of the brain.
TL;DR: The half-times of the disappearance functions of prolactin, LH and FSH in plasma of rats after hypophysectomy were the same as the control values.
Abstract: Extracts of hypothalamic tissue (HE) or of cerebrocortical tissue were infused into stalk portal vessels of anesthetized male rats. The extract of cerebrocortical tissue, equal in weight to ½ of a hypothalamic fragment, had no effect on the release of LH, FSH, or prolactin. HE caused an increase in the levels of LH and FSH in arterial plasma and simultaneously a decrease in the level of prolactin. The responses to HE were related to the concentration of the extract. For example, in rats given HE equivalent to ½1 ⅙, or ½ of a hypothalamic fragment per 30 min, the concentrations of LH in plasma at the end of the infusion period were 2.5, 4.5 and 6.9 times the control values, respectively. The corresponding levels of FSH were 1.6, 2.2 and 2.9, and of prolactin 0.73, 0.55 and 0.37. After the infusion of HE was terminated, the concentrations of LH and FSH in plasma fell and that of prolactin rose. The half-times of the disappearance functions of prolactin, LH and FSH in plasma of rats after hypophysectomy were...
TL;DR: The cultured hypothalamic tissues of the guinea pig that were pulsed with [(3)H]uridine incorporated label into the RNA of neurosecretory neurons, as determined by radioautography and chemical analysis.
Abstract: Fragments of the anterior hypothalamus that contain supraoptic nuclei and short axonal segments from adult guinea pigs have been kept in organ culture for up to 15 days. Electron micrographs displayed intact nuclei, Nissl substance, Golgi bodies, and an ultrastructure characteristic of viable neurosecretory cells; by contrast, the surrounding neurophil showed extensive degeneration. The cultured hypothalamic tissues of the guinea pig that were pulsed with [3H]uridine incorporated label into the RNA of neurosecretory neurons, as determined by radioautography and chemical analysis. Furthermore, and most important, these cells retained a complement of hormones and the ability to incorporate 3H- and 35S-labeled amino acids into vasopressin, neurophysin, and other polypeptides. This incorporation was inhibited by either puromycin or cycloheximide.
TL;DR: The distribution of 14C and 3H labeled thyrotropin-releasing hormone has been studied in mice and rats and administration of a large dose of pyroglutamic acid, histidine and proline, together with the 14C TRH does not decrease the accumulation of the radioactivity in the pituitary.
Abstract: The distribution of 14C and 3H labeled thyrotropin-releasing hormone (TRH) has been studied in mice and rats. In the normal rat, 1-3 hours after the injection of 14C or 3H labeled TRH, the tissue to plasma ratio (T/P) exceeded 1 in the anterior pituitary, liver and kidney. This indicated that radioactivity accumulated in these organs. No accumulation of radioactivity was noted in the cerebral cortex or hypothalamus. Fifteen minutes to 2 hours after injection of 14C or 3H labeled TRH into mice, the T/P ratio showed an accumulation of radioactivity in the whole pituitary gland, liver and kidney but none in the hypothalamus or cerebral cortex. Tritiated proline and histidine, but not glutamic acid, also seem to accumulate in the pituitary. However, administration of a large dose of pyroglutamic acid, histidine and proline, together with the 14C TRH, does not decrease the accumulation of the radioactivity in the pituitary. Extraction followed by chromatography and electrophoresis of the radioactivity found in...
TL;DR: Electrical stimulation of the hypothalamus in 181 mature female Holtzman rats with monopolar electrodes, using 1.0 mA intensity square wave pulses, showed that plasma gro
Abstract: Electrical stimulation of the hypothalamus in 181 mature female Holtzman rats with monopolar electrodes, using 1.0 mA intensity square wave pulses of 5 msec duration and 50 cps, showed that plasma gro
01 Jan 1971