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At least 1,585 records · Page 88Linked to original sources
PubMed1999

Microinjection of leptin into the ventromedial hypothalamus increases glucose uptake in peripheral tissues in rats.

We studied the effects of microinjection of leptin into the ventromedial hypothalamus (VMH) and lateral hypothalamus (LH) on glucose uptake in peripheral tissues in unanesthetized rats. The rate of glucose uptake was assessed in vivo by 2-[3H]deoxyglucose incorporation. Single injection of leptin into VMH increased glucose uptake in brown adipose tissue (BAT), heart, skeletal muscles, and spleen but not in white adipose tissue or skin. On the other hand, microinjection of leptin into LH had little effect on glucose uptake in those tissues. The plasma concentrations of glucose and insulin were unaltered by intrahypothalamic injection of leptin into either VMH or LH. Among skeletal muscles, the increase in glucose uptake induced by intrahypothalamic injection of leptin was greater in the soleus than in the extensor digitorum longus. Likewise, the increased glucose uptake in the gastrocnemius in response to leptin was more prominent in the red part than in the white part of the tissue. When surgical sympathetic denervation of the interscapular BAT was performed, the enhanced glucose uptake by BAT in response to intrahypothalamic leptin was completely suppressed. These findings suggest that intrahypothalamic injection of leptin preferentially increases glucose uptake by some peripheral tissues through activation of the VMH-sympathetic (or its neighboring medial hypothalamus-sympathetic) nervous system, thereby contributing to the maintenance of energy balance.

Adipose Tissue, Brown↗
PubMedDate not supplied

Sensitivity of dopamine receptors in the lateral hypothalamus is altered in 6-hydroxydopamine treated rats.

Amine accumulation is observed in the lateral hypothalamus (LH) after nigrostriatal neurons degenerate. It has been proposed that this accumulation is a source of amines which are released into the hypothalamus thereby affecting the function of adjacent aminergic receptors. To approximate this condition of continuous exposure of LH receptors to endogenous amines, dopamine (DA) was injected into the LH of rats once daily for 5 consecutive days. A control group received 4 daily injections of tartaric acid vehicle and then DA on day 5. Rats pretreated with DA showed severe impairment of open field performance and motor reflex control on day 5 when they were compared to control animals which received vehicle pretreatment. In a second study, the DA receptor antagonist haloperidol was injected into the area of amine accumulation in the LH to determine whether this might block amine release from areas of accumulation thereby to attenuate lesion-induced rotation. Haloperidol administered once daily for 4 out of 7 days, once daily for 7 days or via a continuous infusion for 7 days, all reduced d,l-amphetamine-induced turning to control levels. These results suggest that prolonged exposure of hypothalamic DA receptors alters their sensitivity to subsequent doses of DA and that amine released from areas of accumulation may be blocked by haloperidol to enhance behavioral recovery from DA depleting lesions. Moreover, these findings indicate that the hypothalamus participates in the behavioral effects induced by DA depleting lesions and highlight the importance of hypothalamic pathology in Parkinson's disease.

Animals↗
PubMed2000

[Distribution of dopamine D1 receptors in the paraventricular nucleus of the rat hypothalamus and their colocalization with phosphorylated forms of CREB protein].

The aim of the present immunohistochemical study was to investigate distribution of dopamine D1 receptors in the paraventricular nucleus of hypothalamus and to estimate whether D1 receptors colocalize with pCREB protein, a functional marker of stimulation generated via receptors positively linked to cAMP/PKA system. D1 receptors were found in numerous neurones of the paraventricular nucleus of hypothalamus, especially in its magnocellular part. In double-staining experiment, 74% of all stained neurones showed colocalization of D1 receptors and pCREB protein, 23% of neurones was pCREB-positive only and 3%--D1 receptor-positive only. The presence of D1 receptors in the paraventricular nucleus of hypothalamus indicates that these receptors may be possibly engaged in regulation of the endocrine system (release of oxytocin, vasopressin or CRH). Almost complete colocalization of D1 receptors with pCREB protein suggests that these receptors are likely functional (active). The presence of D1 receptors and pCREB protein in studied structures of rat brain, as well as the specificity of applied antibodies were confirmed by Western Blot method. It was demonstrated that antibodies against D1 receptor and pCREB protein recognized main bands with molecular weight approximately 40 and approximately 46 kDa, respectively, what correlates well with the literature data.

Animals↗
PubMed2001

Ibotenate lesion of the ventromedial hypothalamus lowers hyperthermic effects of prostaglandin E1.

This experiment tested the effects of an intracerebroventricular injection of prostaglandin E1 on the sympathetic activation and the thermogenic changes in rats with ibotenate lesions of the ventromedial hypothalamus. Under pentobarbital anesthesia, twelve Sprague-Dawley male rats were lesioned bilaterally in the ventromedial hypothalamus with an injection of ibotenic acid (30 nmol into each side). Sham lesions were carried out in other twelve control rats. After 48 h, all animals were anesthetized with ethyl-urethane. The firing rate of the sympathetic nerves innervating the interscapular brown adipose tissue and the colonic and interscapular brown adipose tissue temperatures were monitored before and after an intracerebroventricular injection of prostaglandin E1 (500 ng) or saline. Prostaglandin E1 induced an increase in the firing rate of sympathetic nerves and the colonic and interscapular brown adipose tissue temperatures. These effects were reduced by the ventromedial hypothalamic lesion. Since ibotenic acid destroys cell bodies, the findings indicate that neurons of the ventromedial hypothalamus play a considerable role in the control of sympathetic activation and the thermogenic changes during prostaglandin E1 hyperthermia.

Adipose Tissue, Brown↗
PubMed2000

[Effects of xiaopi yishen oral liquid on hypothalamus-pituitary-adrenal gland-thymus axis in stressed rats].

OBJECTIVE: To investigate the effect of Xiaopi Yishen (XPYS) oral liquid on the rats under repeated forced cold water swimming (RFCWS) stress. METHODS: The changes of serum monoamine, ascorbic acid levels in adrenal gland, monoamine levels in hypothalamus and hypophysis, and thymus index were determined. RESULTS: XPYS lowered the increasing of serum DA, 5-HT, improved the reducing of ascorbic acid in adrenal gland and NE, HVA, 5-HT, 5-HITT in hypothalamus and hypophysis of RFCWS-stressed rats. CONCLUSION: The mechanism of XPYS is in connection with the regulation of hypothalamus-pituitary-adrenal gland-thymus axis.

Animals↗
PubMed1999

Glucocorticoids Modulate G-protein alpha-subunit Levels in Rat Hypothalamus.

Glucocorticoids (Gc) affect neuroendocrine function of hypothalamic-pituitary-adrenal axis (HPAA), especially of the hypothalamus. Synthesis and secretion of neuronal hormones of hypothalamus are associated with G-protein-linked signalling system. Here, the regulation by Gc of the levels of several G-protein alpha-subunits in rat hypothalamus was studied with Western blot method. Results showed that Gc downregulated Galphas1, Galphas2,Galphai and Galphaq with different magnitudes, being 14.37,15.66,14.61 and 12.37 per cent, respectively. However, Gc did not affect Galphao expression. Our results provided important information for understanding how Gc alters neuroendocrine function through G-protein-linked signalling system.

Journal Article↗
PubMed1991

Transport of estrogen-induced oxytocin receptors in the ventromedial hypothalamus.

The modulation of oxytocin (OT) receptors (OTRs) by estrogen was investigated in the ventromedial hypothalamus by in vitro receptor autoradiography. Treatment of ovariectomized and adrenalectomized rats with various doses of estradiol benzoate (EB) increased OTR binding not only in the ventromedial nuclei of the hypothalamus (VMN), but also in the area lateral to the nuclei (IVMN). After a single injection of EB, OTRs first were induced within the ventrolateral parts of the VMN, and only hours later they appeared in the IVMN. This is consistent with the interpretation that OTRs are first induced within the estrogen-sensitive neurons of the ventrolateral VMN and then are transported laterally out of the nuclei. Two additional experiments confirmed this interpretation. First, local infusion of a low dose (10 micrograms) of the neuronal transport inhibitor vinblastine blocked the appearance of OTRs in the IVMN but did not prevent the induction of OTRs by EB within the nuclei. Second, a knife cut placed lateral to the VMN prevented the spread of OTRs out of the nuclei. However, even after treatment with a high dose of EB (2 x 10 micrograms), progesterone (P) was required for a maximal extension of the area covered by OTRs. Thus, the OTR is an estrogen-induced neurotransmitter receptor that is transported to its site of action, the lateral ventromedial hypothalamus, where it is modulated by P and where estrogen-induced OT immunoreactivity is found.

Animals↗
PubMed1991

[Beta-lipotropin and beta-endorphin in compensation mechanisms of function after damage of the lateral hypothalamus].

Possibility of restoration of food intake and other related functions impaired after lesion of lateral hypothalamus was studied on 45 male albino non-strain rats divided into 3 groups with 15 per each. Neuropeptides beta-lipotropin (beta-LPT) and its derivative beta-endorphin were used as compensation factors. The parameters recorded were: volume of food and water intake, diuresis, body weight and temperature, frequencies of rest periods, comforting forms of behavior and orienting-exploratory activity. The results revealed that lesion of lateral hypothalamus resulted in the formation of specific central and peripheral syndrome responsible for the impairment of food intake and other related functions. Intracerebroventricular injections of beta-LPT and beta-endorphin facilitated compensation of impaired functions caused by lesion of lateral hypothalamus. The data were analyzed on the basis of the systems approach to the organism's physiological functions.

Animals↗
PubMed1990

[The reactions of the respiratory neurons of the medulla oblongata to the burst stimulation of the hypothalamus].

The responses of inspiratory and expiratory neurons of the ventral respiratory nucleus to stimulation of postero-lateral hypothalamus at different phases of respiratory cycles, were studied in anesthetized cats. The stimulation in the first half of the inspiratory cycle evoked excitatory responses in 72% of inspiratory neurons and an inhibitory type of responses in 28%. The stimulation during the second half of the inspiratory phase did not change significantly the patterns of inspiration. The stimulation of the hypothalamus during expiratory phase depressed the activity of expiratory neurons and reversed the phases of the respiratory cycle. Recording of the unit activity of inspiratory neurons revealed an extra burst of spikes in response to stimulation of the hypothalamus in different moments of expiratory phase. Possible neuronal mechanisms of hypothalamic influence on switching off of the expiration and switching on of the inspiration, are discussed.

Action Potentials↗
PubMed1986

[Monoamines and peptidergic Gomori-positive neurosecretory cells of the paraventricular nucleus of the rat hypothalamus in chronic alcohol consumption].

For 6 months the rats were kept on 20 degrees ethanol. Then, the rats could choose whether to drink alcohol (A) or water. The rats formed 2 groups: those preferring A and those preferring water. The control rats were kept on water. The function of hypothalamus monoamine- and peptidergic systems were disturbed following chronic A treatment. Alcohol-preferring, unlike water-preferring rats, have revealed higher hypothalamus levels of serotonin and lower levels of dopamine and noradrenaline, which correlated with changes in fluorescence intensity of hypothalamus noradrenaline structures and were accompanied by remarkable disturbances in nonapeptide neurohormone transport in the paraventricular nucleus region.

Alcohol Drinking↗
PubMed1983

[Influence of renin on the effects of electric stimulation on the ventromedial hypothalamus].

The influence of intraventricular injection of different doses of renin on the effects of electrical stimulation of the ventromedial hypothalamus was studied. Injection of renin (10 micrograms/kg) into the lateral ventricles of the brain of experimental animals elicited a prolonged elevation of arterial pressure and a decrease of the heart rate, while given in doses of 20 and 30 micrograms/kg it also provoked arrhythmias and ventricular extrasystoles, and a lowering of the threshold of ventromedial hypothalamus stimulation. It was found that under the central action of renin, a short-term stimulation of the ventromedial hypothalamus provoked ventricular extrasystoles.

Animals↗
PubMed1982

[Role of the lateral hypothalamus in the genesis of somato-autonomic responses].

Coagulation of medial and lateral parts of the lateral hypothalamic area increases latency of responses and decreases respiration, arterial blood pressure and heart rate responses to stimulation of the hypothalamic ventromedial nucleus. Coagulation of the perifornical region of the lateral hypothalamus completely eliminates the above autonomic responses. A new rigid integration which is characterized with the increased number of correlated relations between separate components of somato-autonomic responses, was postulated after correlation analysis of somato-autonomic parameters during stimulation of hypothalamic ventromedial nucleus in animals with lateral hypothalamic lesions. The data suggest that somato-autonomic responses to stimulation of negative emotion sites of the hypothalamus are mediated by those brain structures which are under ascending excitatory influences of the lateral hypothalamus.

Animals↗
PubMed1980

Effect of LH-RH, gonadotrophins or sex hormones on protein synthesis in hypothalamus and pituitaryof immature female rat in vitro.

Protein synthesis in cerebral cortex, hypothalamus and pituitary of immature female rats was studied after treatment with 5 doses of LH-RH, gonadotrophins or sex hormones. None of the hormonal doses affected protein synthesis in cortex. Sex hormones and gonadotrophins increased protein synthesis in hypothalamus. These effects are attributed to positive feed-backs of these hormone on immature female rat hypothalamus. All treatments increased protein synthesis in pituitary. The direct effect of LH-RH on pituitary and the feed-back effect of sex hormones or gonadotrophins are compared and discussed.

Animals↗
PubMed1994

[The dopaminergic and serotoninergic components of the self-stimulation reaction of the lateral hypothalamus in rats with disruption of the medial prefrontal cortex].

Amphetamine (1 mg/kg) promoted a pedal self-stimulation of lateral hypothalamus of Wistar rats in the Skinner box. An unipolar lesion of medical prefrontal cortex with kainic acid 10-14 days prior to an experiment did not prevent the facilitating effect of amphetamine on self-stimulation, though the levels of hypothalamic noradrenaline and dopamine are 43% and 4.5-fold decreased respectively, the hypothalamic serotonin concentration not changing. Lysergic acid diethylamid (10 mkg/kg) did not influence on self-stimulation response in rats with damaged medial prefrontal cortex, but after preliminary administration prevented the stimulating effect of amphetamine on self-stimulation of lateral hypothalamus. The data are discussed from the point of view of a hypothesis that the phenomenon obtained is associated with the presence of a hypothalamic autoregulatory dopaminergic system providing the realization of self-stimulation. However, it does not exclude that the modulating influence of medial prefrontal cortex on lateral hypothalamus is connected with not only dopaminergic but with serotoninergic axons too.

Amphetamine↗
PubMed1995

[Modulation of norepinephrinergic control of hypothalamus preoptic areas on hibernation bouts in ground squirrels (Citellus dauricus)].

In our previous work, it was shown that hibernation could be enhanced by injection of 6-hydroxydopamine (6-OHDA, 200 micrograms) into the lateral cerebral ventricle of ground squirrels by destructing norepinephrine (NE) nerve terminals in brain areas including hypothalamus, cerebral cortex, hippocampus and periaqueductal gray matter of middle brain. In order to identify the specific area contributing for the modulation of NE system on hibernation, small doses of 6-OHDA (4 micrograms) were microinjected bilaterally into medial preoptic hypothalamus (MPA), lateral preoptic hypothalamus (LPA) and ventromedial hypothalamic nucleus (VMH). The results showed: (1) Depletion of NE on MPA may facilitate hibernation. (2) Little effect was seen by microinjection of 6-OHDA into LPA. (3) The effect of 6-OHDA on VMH was similar to that on MPA, through the mechanism remains to be investigated.

Animals↗
PubMedDate not supplied

[Effects of hypothalamic mediator systems on the hormonal changes in rabbit blood during prolonged electric stimulation of emotiogenic zones of the hypothalamus].

Changes in the blood hormonal levels were studied in 36 rabbits with electrodes implanted to the area of the dorsomedial nuclei of the hypothalamus in the course of a 5-cycle electrostimulation experiment. After each period blood hormonal levels were correlated to the activities of the hypothalamic catecholamine-, GABA-, and serotoninergic systems. The first two cycles of the experiment were associated with a high activity of the hypothalamic mediator systems and with increased levels of all hormones in the blood. The functional activity of the hypothalamus was reduced due to the predominance of stress-limiting systems. The initial reduction of GABA, and then of serotonin in the hypothalamus caused be the end of experiment a reduction of the blood levels of the tested hormones, except the Ca-regulating ones and active renin. Disturbances in the regulatory mechanisms of hypothalamic mediator systems leads to an increase in its excitability and to transformation of the adaptive pattern of hormonal changes into pathological mechanisms of prolonged emotional stress.

Animals↗
PubMed1995

Harmful effects of MSG on function of hypothalamus-pituitary-target gland system.

It has been demonstrated that neonatal administration of monosodium glutamate (MSG) results in a clearly defined lesion of the arcuate nucleus (AN) of the hypothalamus. The present study shows that fat was accumulated in the abdomen of male rats treated with MSG; weights of the body, pituitary and testis were lower; beta-EP content in hypothalamus decreased while L.EnK content increased; serum LH, FSH, TSH, GH and TS levels all decreased in varying degrees while serum PRL level significantly increased. The cAMP content lowered in pituitary, but nor in testes; clear histological changes occurred in testicular tissue; Se-GSH-Px activity in both testis and adrenal gland lowered while LPO level significantly increased. Both Se-GSH-Px activity and LPO level in liver increased. These results indicate that MSG is harmful to the function of the hypothalamus-pituitary-target system of neonatal rats.

Adrenal Glands↗
PubMedDate not supplied

[The functional asymmetry of the rabbit lateral hypothalamus during food motivation].

Thresholds and stability of food motivational reactions induced by electrostimulation of the left and right hypothalamus were studied in rabbits. Food reactions evoked by stimulation of the left hypothalamus had the lower thresholds and higher stability than those evoked by the stimulation of symmetrical areas. The asymmetry of the lateral hypothalamus in food reactions was not correlated with motor and sensory asymmetric.

Animals↗