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At least 19 recordsLinked to original sources
PubMed1981

Effects of glycine on serum gonadotropins and estradiol and on concentrations of free amino acids in the middle hypothalamus in female rats.

The effects of glycine on serum gonadotropins and estradiol (E2) and on concentrations of free amino acids in the middle hypothalamus have been studied in diestrus-1 rats. 20 min after intraperitoneal administration, glycine in doses of 50 and 100 mg had no significant effect on serum luteinizing hormone (LH) levels, but 200 mg significantly elevated serum LH levels. Glycine in doses of 50-200 mg had no effect on serum follicle-stimulating hormone levels at 20 min after intraperitoneal injection. 200 mg of glycine significantly elevated serum LH levels at 20 and 50 min and serum E2 levels at 50 and 80 min after intraperitoneal injection. The effects were maximal at 20 min after injection for LH and at 50 min after injection for E2. 20 min after intraperitoneal injection, 200 mg of glycine significantly increased the concentration of glycine in the middle hypothalamus, but had no effect on the concentrations of the other free acidic and neutral amino acids in the middle hypothalamus. These results suggest that glycine may play a role in the neural regulation of LH secretion.

Amino Acids↗
PubMedDate not supplied

[The effect of the hypothalamic motivational centers on the function of the cortical visual area of the hemispheres].

Chronic experiments were carried out in waking rabbits. A single stimulation of the middle hypothalamus (the ventromedial, VMN, and the lateral, LN, nuclei) was shown to induce the phasic action on a formation of the primary response (PR) of the visual cortex (VC) to the testing light flash. At the first phase (1-43 ms for the VMN and 1-10 ms for the LN) the hypothalamic-cortical responses completely inhibited the formation of the VC response to the light stimulus. At the second phase (43-130 ms for the VMN and 10-150 ms for the LN) they selectively and rather significantly facilitated the formation of the positive PR component the negative one being suppressed. This suppression was stronger and longer during the stimulation of the VMN, than that of the LN (140 and 50 ms correspondingly). The data obtained suggested the existence of a highly organized apparatus of the phasic (both by the VMN and LN) control of the VC function being realized both by means of facilitatory axo-somatic mechanisms at the level of the basal dendrites of the layer IV cortical neurons, and by means of the inhibitory mechanisms at the level of the apical dendrites of the superficial cortical layers.

Animals↗
PubMed1985

Electrical self-stimulation deficits in the anterior and posterior parts of the medial forebrain bundle after ibotenic acid lesion of the middle lateral hypothalamus.

The aim of the present study was to analyse the involvement of the intrinsic neurons located in the middle lateral hypothalamus in electrical self-stimulation measured with electrodes in the anterior and posterior parts of the medial forebrain bundle. In rats without hypothalamic lesions, self-stimulation rates from both anterior and posterior electrodes were similar on either side of the brain. For all rats with ibotenic acid-induced lesions in the lateral hypothalamus, self-stimulation rates were lower with electrodes in the area of the lesion, while self-stimulation on the contralateral side was normal. In rats with electrodes in the anterior hypothalamus, the lesion produced a large deficit when stimulation was applied to the anterior electrode ipsilateral to the lesion. Only three rats showed a decrease in self-stimulation with stimulation of the posterior hypothalamic electrode ipsilateral to the lesion; self-stimulation of the other three rats was normal. These results suggest that self-stimulation in the anterior part of the medial forebrain bundle is supported by long fibers originating in the middle part of the lateral hypothalamus, while self-stimulation in the posterior part of the lateral hypothalamus can be influenced by another system not involved in reward processes observed in the rostral part of the medial forebrain bundle.

Animals↗
PubMed2003

Different electroclinical manifestations of the epilepsy associated with hamartomas connecting to the middle or posterior hypothalamus.

PURPOSE: The epilepsy associated with hypothalamic hamartomas (HHs) has typical clinical, electrophysiologic, and behavioral manifestations refractory to drug therapy and with unfavorable evolution. It is well known that only sessile lesions produce epilepsy, but no correlation has been established between the different types of sessile hamartomas and the diverse manifestations of the epilepsy. We correlate anatomic details of the hamartoma and the clinical and neurophysiologic manifestations of the associated epilepsy. METHODS: HHs of seven patients with epilepsy (ages 2- 25 years) were classified as to lateralization and connection to the anteroposterior axis of the hypothalamus by using high-resolution brain magnetic resonance imaging. We correlated the anatomic classification with the clinical and neurophysiologic manifestations of the epilepsy as evaluated in long-term (24 h) video-EEG recordings. RESULTS: HHs ranged in size from 0.4 to 2.6 cc, with complete lateralization in six of seven patients. Ictal manifestations showed good correlation with the lobar involvement of ictal/interictal EEGs. These manifestations suggest the existence of two types of cortical involvement, one associated with the temporal lobe, produced by hamartomas connected to the posterior hypothalamus (mamillary bodies), and the other associated with the frontal lobe, seen in lesions connecting to the middle hypothalamus. CONCLUSIONS: A consistent clinical and neurophysiologic pattern of either temporal or frontal lobe cortical secondary involvement was found in the patients of our series. It depends on whether the hamartoma connects to the mamillary bodies (temporal lobe cases) or whether it connects to the medial hypothalamus (frontal lobe cases).

Adolescent↗
PubMed1985

Distribution and release of immunoreactive thyroid-stimulating hormone in the rat hypothalamus: effects of thyroidectomy, hypophysectomy and treatment with thyroid hormones.

Immunoreactive thyroid-stimulating hormone (IR-TSH) has been detected in the hypothalamus and is released in vitro by a calcium-dependent mechanism when the tissue is depolarized. Recently, immunocytochemical studies have revealed that IR-TSH is present in thyrotropes in the pars tuberalis. Therefore, because these thyrotropes are associated with the median eminence, the area with the highest concentration of IR-TSH, it is of interest to determine if 'hypothalamic' IR-TSH is from neural or pituitary cells. We addressed this issue by studying the effects of hypophysectomy, thyroidectomy, or chronic administration of triiodothyronine (T3) or thyroxine (T4) on the distribution and in vitro release of IR-TSH in the hypothalamus. We reasoned that, if hypothalamic IR-TSH is dependent on the thyrotropes of the pars tuberalis, then changes in hypothalamic IR-TSH concentration and release should be parallel to those measured in pituitary extracts. IR-TSH was measured in tissue extracted in ice-cold 2% NaCl, with a final pH of 4.5. For the in vitro studies, tissues were incubated for 20-min periods in Krebs-Ringer bicarbonate buffer at 37 degrees C. In untreated rats, the concentration of IR-TSH is greater in the ventral than the dorsal portion of the hypothalamus (39.3 +/- 8.2 vs. 4.0 +/- 1.5 ng/mg wet wt.). Upon finer dissection of the hypothalamus into median eminence and anterior, middle, and posterior portions of the remainder, IR-TSH was only detectable in the middle hypothalamus (5.3 +/- 1.5 ng/mg), and the median eminence (149 +/- 41 ng/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1961

Distinct "feeding" and "hunger motivating" systems in the lateral hypothalamus of the rat.

Electrodes were implanted in the middle hypothalamus of rats to determine the neural organization of the "feeding" centers. Stimulations of the farand midlateral hypothalamic area produced feeding responses in sated animals, but only the former caused sated animals to cross an electrified grill to press a lever for food. After lesions had been made in the medial forebrain bundle, however, stimulations in the far-lateral hypothalamic area resulted in feeding in sated animals but failure to cross the electrical barrier to press a lever for food. Simultaneous far-lateral and "satiety" center stimulations produced feeding in sated animals but failed to "motivate" grill-crossing behavior.

Animals↗
PubMed1981

Brain stem sites mediating specific and non-specific temperature effects on thermoregulation in the pekin duck.

1. Thermodes were chronically implanted into various levels of the brain stem of sixteen Pekin ducks. The effects of local thermal stimulation on metabolic heat production, core temperature, peripheral skin temperature and respiratory frequency were investigated. 2. Four areas of thermode positions were determined according to the responses observed and were histologically identified at the end of the investigation. 3. Thermal stimulation of the lower mid-brain/upper pontine brain stem (Pos. III) elicited an increase in metabolic heat production, cutaneous vasoconstriction and rises in core temperature in response to cooling at thermoneutral and cold ambient conditions and, further, inhibition of panting by cooling and activation of panting by heating at warm ambient conditions. The metabolic response to cooling this brain stem section amounted to -0.1 W/kg. degrees C as compared with -7 W/kg. degrees C in response to total body cooling. 4. Cooling of the anterior and middle hypothalamus (Pos. II) caused vasodilatation in the skin and did not elicit shivering. The resulting drop in core temperature at a given degree of cooling was greater than the rise in core temperature in response to equivalent cooling of the lower mid-brain/upper pontine brain stem. 5. Cooling of the preoptic forebrain (Pos. I) and of the myelencephalon (Pos. IV) did not elicit thermoregulatory reactions. 6. It is concluded that the duck's brain stem contains thermoreceptive structures in the lower mid-brain/upper pontine section. However, the brain stem as a whole appears to contribute little to cold defence during general hypothermia because of the inhibitory effects originating in the anterior and middle hypothalamus. Cold defence in the duck, which is comparable in strength to that in mammals, has to rely on extracerebral thermosensory structures.

Animals↗
PubMed1978

Changes in hypothalamic LH-RH content and blood levels of LH-RH, gonadotropin and estradiol during the preovulatory stage of rat estrous cycle.

In order to investigate the sequence of events concerning gonadotropin surge, serum LH, FSH and estradiol concentrations were measured during the rat estrous cycle as well as hypothalamic and blood levels of LH-RH in the preovulatory stage. Normally cyclic female Wistar rats kept on 12 hr light (from 22.00 hr to 10.00 hr) and 12 hr dark were killed at different times of day during each stage of the cycle. The hypothalamus was quickly dissected out, divided into 3 portions (the anterior, middle and posterior) and extracted in 90% methanol. Blood LH-RH was extracted by affinity chromatography prior to radioimmunoassay. The content of LH-RH in the anterior and middle hypothalamus started to decrease between 1.00 hr-3.00 hr, reached its nadir at 6.00 hr on proestrus and recovered to its previous values on estrus. Almost simultaneously blood LH-RH concentration showed an increase of 18.3 pg/ml-8.8 pg/ml between 1.00 hr-3.00 hr, and then fell to less than 1.0 pg/ml at 6.00 hr. On the other hand, serum estradiol level began to elevate on diestrus II followed by its peak at 6.00 hr on proestrus, while the peaks of serum LH and FSH were observed at 8.00 hr and 10.00 hr, respectively. These studies indicate that the elevation of serum estradiol was followed by the release of LH-RH from the hypothalamus and the LH-RH may be responsible for the preovulatory discharge of gonadotropin.

Animals↗