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Results for “Hypothalamic Area, Lateral”

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At least 19 recordsLinked to original sources

PubMed1992

[The effect of the lateral hypothalamic area on the pulmonary surfactant system].

The level of lipids, lipase activity and lungs' blood capacity were studied on 62 rats. Dispersal cobalt was infused into the hypothalamic lateral area of rats with adrenalectomy or injected with droperidol, obsidan, reserpine. Their effect upon the hypothalamus involved a decrease in surfactant phospholipids and lung's blood capacity. Possible adrenergic mechanisms of affecting the lung surfactant system are discussed.

Adrenalectomy↗

PubMed1988

Neurons in the lateral hypothalamic area and zona incerta with ascending projections to the subfornical organ area in the rat.

Sixteen neurons in the lateral hypothalamic area (LH) and 12 neurons in the zona incerta (ZI) were antidromically activated by electrical stimulation of the subfornical organ (SFO) area in urethane-anesthetized male rats. The activity of these LH and ZI units was examined for response to intracarotid injections of isotonic (0.15 M NaCl solution, 0.05 ml) or hypertonic (0.18 M or 0.3 M NaCl solution, 0.05 ml) saline. All the units did not change their activity to the injections of isotonic saline. Of these units, 9 LH and 5 ZI units displayed an increase and 2 LH and 3 ZI units exhibited a reduction in neuronal activity following the injections of hypertonic saline, while the remaining 5 LH and 3 ZI units were unresponsive. The present results suggest that the LH and ZI neurons with ascending projections to the SFO may carry the information from osmoreceptive elements for modulating the actions of the SFO.

Afferent Pathways↗

PubMed1990

Inhibition of gastric acid secretion by cholinergic stimulation of the lateral hypothalamic area.

Cholinergic stimulation of the lateral hypothalamic area with carbachol (1 microgram in 1 microliter) markedly inhibited gastric acid secretion in the anesthetized rat. Inhibition was blocked by prior micro-injection of atropine (4 micrograms/microliters) into the same brain area and was accompanied by an increased sodium content in the stomach. Muscarinic receptor mediated cholinergic inhibitory influence of the hypothalamus on gastric acid secretion is suggested by these results.

Animals↗

PubMed1986

Lateral hypothalamic area stimulation excites neurons in the region of the subfornical organ with efferent projections to the hypothalamic paraventricular nucleus in the rat.

Fifteen neurons in the region of the subfornical organ (SFO) were antidromically activated by electrical stimulation of the paraventricular nucleus (PVN) in the rat. Electrical stimulation of the lateral hypothalamic area (LHA) excited the activity of 9 of the identified units, but did not affect the remaining units. The excitatory response of the identified units was blocked by microiontophoretically (MIPh) applied saralasin (Sar), an angiotensin II (ANGII) antagonist, but not by atropine (Atr), a muscarinic antagonist. These results suggest that the LHA has an excitatory influence on the activity of neurons in the region of the SFO with efferent projections to the PVN and that the influence may be mediated by ANGII receptors.

Angiotensin II↗

PubMed1990

Effects of electrical stimulation of the central nucleus of the amygdala and the lateral hypothalamic area on the oval nucleus of the bed nuclei of the stria terminalis and its adjacent areas in the rat.

Our recent studies demonstrated that there are reciprocal connections between the oval nucleus (Ov) of the bed nuclei of the stria terminalis (BST) and the central nucleus of the amygdala (Ce) or the lateral hypothalamic area (LHA). The present experiments found that spontaneous unit discharges of 73 neurons in the Ov and its adjacent areas were modified in 58 neurons (79.45%) by focal brain stimulation in the Ce. After focal LHA stimulation, the spontaneous unit discharges of 23 (53.49%) of 43 Ov neurons, which could be influenced by focal Ce stimulation, were changed. Thirteen Ov neurons were antidromically activated by focal Ce or LHA stimulation. These results indicate that: (1) neuronal activities in the Ov and its adjacent areas can be modulated by Ce or LHA; (2) there are functional reciprocal connections between Ov and Ce or LHA; and (3) the Ce and LHA afferents converge upon some Ov neurons.

Action Potentials↗

PubMed1988

RNA content of neurons in the ventromedial nuclei and lateral hypothalamic area relative to feeding status.

The total RNA content of hypothalamic and cortex neurons in relation to the feeding status of adult male Wistar rats was studied. Experimental conditions including food deprivation (12 and 24 hours) and relative satiation (short-term refeeding, glucose or glycerol administration) changed in different ways the total RNA content of the neurons in the ventromedial hypothalamic nuclei (VMH) and in the lateral hypothalamic area (LHA) with respect to fasting or satiety. Only the long-term absence of food (24 hours) significantly increased the total RNA content of the VMH cells, while the RNA content of the LHA neurons significantly decreased in both the 12 and 24 hr fasted rats compared with those fed ad lib. The sixty minute free access to food after 12 or 24 hours of fasting fully reversed these changes. The short-term food intake significantly increased the RNA content of the LHA cells of the 12 and 24 hr fasted animals while the total RNA content of the VMH neurons significantly decreased only in the 24 hr fasted rats. The effect of glucose and glycerol administration on the RNA content of the LHA neurons (in 12 hr fasted rats) was similar to the effect of refeeding. One hour after giving glucose (1 g/kg b.wt.) or glycerol (300 mg/kg b.wt.) the total RNA content in the LHA neurons significantly increased. No changes in RNA content were observed in the neurons of the cortex when comparing the experimental and control rats. The results demonstrated the close relationship between the RNA content of the hypothalamic neurons and the feeding status.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Modifications of the electrical activity in the ventromedial hypothalamic nucleus and the lateral hypothalamic area of 24-hour food-deprived rats.

The amplitude of the electrical activity of the ventromedial hypothalamic nucleus (VMH) and lateral hypothalamic area (LH) was evaluated in rats after 24-hr food deprivation to determine the effects of the diet they had received before fasting. Bioelectrical potentials were registered by means of monopolar electrodes. In rats after 24-hr food deprivation an increase in the absolute values of the amplitude of the electrical activity of the VMH and LH was found; this effect was more pronounced in the LH. Comparing the amplitude of the electrical activity of the VMH and LH, we found it to be always higher in the VMH in ad libitum fed rats, while in 24-hr food-deprived rats the electrical activity was always higher in the LH. The extent of changes depended on the diet the rats had received before fasting--they were most marked in rats fed on a high-protein diet and less marked in rats fed on either a standard or a high-fat diet before food deprivation.

Animals↗

PubMed1979

An autoradiographic study of the efferent connections of the lateral hypothalamic area in the rat.

The efferent connections of the lateral hypothalamic area (LHA) have been analyzed in a series of 30 rat brains with injections of 3H-amino acids into different parts of the area and the surrounding regions. Our findings indicate that all parts of the LHA contribute ascending and descending fibers to the medial forebrain bundle, and also project medially to certain of the adjoining hypothalamic nuclei. All levels of the LHA appear to send some fibers to a continuous group of structures that extends from the medial septal-diagonal band complex rostrally, through the lateral preoptic and lateral hypothalamic areas to the mammillary complex and the ventral tegmental area caudally. In addition, it is evident that cells at different levels within the LHA may have differential projections. Thus, the anterior and lateral parts of the LHA also appear to project substantially to the anterior hypothalamic area, the ventromedial and dorsomedial hypothalamic nuclei, the parataenial and paraventricular nuclei of the thalamus, and the medial part of the lateral habenular nucleus. Similarly, cells in the tuberal and posterior parts of the LHA project to the central gray, the longest projections from the posterior region reaching as far caudally as the central tegmental field, the parabrachial nucleus, the locus coeruleus, and the superior central and dorsal nuclei of the raphe. Viewed as a whole, the LHA is therefore well-suited to integrate inputs from the limbic system and brainstem and to relay them on the one hand to the medial zone of the hypothalamus and on the other to virtually every structure closely associated with the medial forebrain bundle and to the nuclei of origin of the major ascending monoaminergic systems.

Animals↗

PubMed1991

Increased neuropeptide Y concentrations in the lateral hypothalamic area of the rat after the onset of darkness: possible relevance to the circadian periodicity of feeding behavior.

Neuropeptide Y (NPY) is a major hypothalamic peptide which powerfully stimulates feeding when injected into the hypothalamus and is implicated in circadian rhythmicity. To investigate whether NPY is involved in the increased feeding that follows the onset of darkness in rats, NPY levels were measured in discrete hypothalamic areas before and after darkness. Four groups of eight adult female Wistar rats were habituated to a 12:12 hour light:dark cycle, with food presented at the onset of darkness (19.00 hours). One group was sacrificed during the 3 hours before darkness and another in the first 2.5 hours after darkness, with food provided as usual. To distinguish any effects of feeding itself, the study was repeated with two further groups, but food was not provided after darkness. Seven hypothalamic regions were microdissected from slices of fresh brain and acid-extracted for radioimmunoassay of NPY. NPY levels (fmol/microgram protein) were significantly higher (p less than 0.01) in the lateral hypothalamic area (LHA) of the dark-phase group in both studies. In the other six regions, NPY levels did not differ between light and dark phases. The LHA regulates the circadian rhythmicity of feeding and NPY injection here stimulates feeding. Alterations in NPY in the LHA around the onset of darkness may be related to the initiation of dark-phase feeding.

Animals↗

PubMed1985

Morphometry of cytoarchitecture of the lateral hypothalamic area in the rat.

The cytoarchitecture of the lateral hypothalamic area (LHA) in rats was studied with cresyl violet-stained coronal celloidin sections and with sections of the brain impregnated by a Golgi method. Unimodality was established in the frequency distribution histogram of both the somatic cross-sectional area of the LHA neurons and somatic shape (elongation and circularity). The predominant somatic orientation was in the dorsomedial-ventrolateral direction: bimodality of the frequency distribution of somatic orientation was denied. These findings suggest that the LHA neurons examined in the present study are not subdivisible on the basis of the somatic area, shape or orientation. Although the neurons were classified into eight types based upon the dendritic pattern, those in the LHA largely consisted of only three of them; Type III (dendrites extending in two directions along the long axis of soma), Type IV (three directions) and Type VIII (four directions) jointly accounted for 97.1 percent of the total neurons examined. This finding suggests that the parameter of dendritic pattern serves an important purpose in the typing of the rat LHA neurons. The orientation of intrinsic dendrites and intrinsic axons in the LHA has also been described.

Animals↗

PubMed1987

A topographical analysis of the origin of some efferent projections from the lateral hypothalamic area in the rat.

Some projections from the lateral hypothalamic area in the rat have been investigated, using combinations of fluorescent tracers, injected into several different parts of the central nervous system. Projections appear to arise from loosely organized assemblies of neurons, called sets and from more densely packed assemblies, called clusters. The sets and clusters vary considerably in position and in distinctness of their borderlines. Even within extensive and vaguely defined sets, however, high concentrations of labeled neurons may be present at specified sites in the lateral hypothalamus. Such concentrations are observed in the transitional area of the zona incerta and the dorsal part of the lateral hypothalamus, and in the ventrolateral part of the hypothalamus, bordering the cerebral peduncle and the subthalamic nucleus, in both cases after injections into some "autonomic centers" in the brainstem, such as the parabrachial nuclei and the dorsal vagal complex. Sets and clusters may overlap considerably. Within the fields of overlap the number of double labeled neurons may vary from almost zero up to more than 50%, depending on the injection sites. The results show that different parts of the lateral hypothalamus in the rat have different efferent relationships. Combination of the results of the present study with known data concerning the afferent relationships, the cytoarchitecture and behavioral functions of the lateral hypothalamic area, suggests that different parts of this entity are involved in different regulatory and behavioral functions.

Animals↗

PubMed1986

Angiotensin II-sensitive neurons in the rat lateral hypothalamic area with efferent projections to the subfornical organ.

Thirteen neurons in the lateral hypothalamic area were antidromically activated by electrical stimulation of the subfornical organ in the rat. The activity of almost all identified neurons (N = 11) was excited by microiontophoretically applied angiotensin II. On the other hand, of the antidromically unidentified lateral hypothalamic area neurons (N = 10) tested, 4 were excited by microiontophoretically applied angiotension II and 6 were not affected. The excitatory responses of identified and unidentified lateral hypothalamic area neurons to angiotensin II were blocked by microiontophoretically applied saralasin, an angiotensin II antagonist.

Action Potentials↗

PubMed1992

Metabolic and neuroendocrine indices one month after lateral hypothalamic area lesions.

Mature male rats received bilateral electrolytic lateral hypothalamic area lesions (LHAL) or were sham-operated fed ad lib (CON-ADLIB) or sham-operated pair-fed/gained (CON-PF) to LHAL rats. One month later all rats were sacrificed. Rats with LHAL were hypophagic and had reduced body carcass fat, testes, livers, epididymal fat pads (PADS), diaphragms (DIA), and body weight compared to CON-ADLIB. In the liver, LHAL rats incorporated more C14-U-glucose carbon (GLUCINC) into lipid and glycogen than both CON groups, but GLUCINC was similar among CON groups. In PADS, LHAL rats oxidized more glucose carbon (GLUCOX) than CON-ADLIB but less than CON-PF/PG. The latter showed greater GLUCOX than CON-ADLIB. In DIA, LHAL and CON-PF/PG showed reduced GLUCINC into glycogen vs. CON-ADLIB. Plasma glucose was similar among groups, but insulin was lower in LHAL and CON-ADLIB than in CON-PF/PG. Rats with LHAL had lower plasma T3 concentrations than CON-ADLIB, but similar T3 levels compared to CON-PF/PG. Several of the metabolic changes in LHAL rats could be due to hypophagia; however, four out of nine metabolic indices, glucose carbon incorporation into liver lipid and glycogen and epididymal fat pad lipid and oxidation, were significantly different from CON-PF/PG, i.e., they were independent of food intake. Possibly then, they are due to a lesion effect other than on feeding mechanisms. Some aspects of metabolism that were previously found to be altered 48 h after LHAL were recovered, whereas others apparently were not.

Adipose Tissue↗

PubMed1990

Inhibition of renal electrolyte excretion by gabaergic pathways of the lateral hypothalamic area.

Injection of gamma amino butyric acid (GABA) into the lateral hypothalamic area of unrestrained conscious rats caused a decrease in renal electrolyte excretion with an increase in urinary flow. When picrotoxin, a specific inhibitor of gabaergic pathways, was administered, a significant increase in renal water and electrolyte excretion occurred. The effect of simultaneous injection of picrotoxin and GABA into the same site indicated that picrotoxin was less potent in reversing the effect induced by GABA than GABA was in reversing the effect of picrotoxin. We conclude that GABA acts directly on the neuronal mechanisms involved in the control of water and electrolyte excretion, perhaps by exerting a tonic inhibitory action on renal electrolyte excretion.

Animals↗

PubMed1989

Cardiovascular effects produced by L-glutamate stimulation of the lateral hypothalamic area.

L-Glutamate microinjections into the tuberal region of the lateral hypothalamic area (LHAt) caused a fall in blood pressure and heart rate in pentobarbital-anesthetized rats. The bradycardia was mediated by both beta-adrenergic and muscarinic mechanisms as demonstrated with pharmacological blockade. The hypotension was due to a decrease in cardiac output, not a decrease in total peripheral resistance. In addition, there was a reduction in coronary blood flow. If heart rate was held constant by pharmacological blockade or by electrical cardiac pacing, L-glutamate stimulation of the LHAt still caused a fall in blood pressure. When the electrically paced model was used, this hypotension was due to a fall in cardiac output. In contrast, with the pharmacological blockade of the heart, the hypotension was due to a decrease in the total peripheral resistance. The cardiac output reduction in the paced condition was not mediated solely by either beta-sympathetic or parasympathetic mechanisms as determined by pharmacological blockade. With heart rate held constant by either drugs or pacing, LHAt stimulation did not alter regional blood flow or resistance in any vascular bed, including the coronary circulation. We conclude that L-glutamate stimulation of the LHAt lowers the cardiac output and heart rate by both parasympathetic and beta-adrenergic mechanisms and elicits hypotension by lowering cardiac output in the naive and electrically paced model.

Animals↗

PubMedDate not supplied

Changes in urinary electrolytes excretion after injections of ionic solutions into lateral hypothalamic area of rats.

Rats submitted to a chronically implanted cannula into lateral hypothalamic area (LHA) were utilized to study the effect of ionic stimulation of KCl, LiCl and CaCl2, sodium free solutions, on renal water and electrolyte excretion. In a general way decreases in natriuresis and kaliuresis following the injections of solutions into LHA were observed. Furthermore, significant increases in diuresis were noted after the injections of the 0.30 M solutions.

Animals↗

PubMed1990

[The functional connection of rat habenular nucleus and lateral hypothalamic area in the regulation of cardiovascular activities].

The electrical stimulation of the lateral hypothalamic area (LH) in the rat elicited an obvious rise of the arterial pressure and increase in the heart rate. After the microinjection of lidocaine hydrochloride into the habenular nucleus (Hb) on the same side of the electrode, the vasopressor effect elicited by the electrical stimulation of the LH was blocked by 38.9% and the effect on heart rate was reduced by 44.4%. After the microinjection of lidocaine hydrochloride into the bilateral Hb, the vasopressor effect elicited by the electrical stimulation of the LH was blocked by 40.7% and the effect on heart rate was reduced by 41.2%. After the microinjection of the artificial cerebrospinal fluid into the unilateral or bilateral Hb, the cardiovascular effect elicited by the electrical stimulation of the LH was not affected. The electrical stimulation of the Hb in the rat elicited an obvious rise of the arterial pressure, but the heart rate was not changed significantly. After the microinjection of lidocaine hydrochloride into the LH on the same side of the electrode the vasopressor effect elicited by the electrical stimulation of the Hb was blocked by 63.2%. After the microinjection of lidocaine hydrochloride into the bilateral LH the vasopressor effect elicited by the electrical stimulation of Hb was blocked by 62.6%. After the microinjection of the artificial cerebrospinal fluid into the unilateral or bilateral LH, the cardiovascular effect elicited by the electrical stimulation of the Hb was not affected. The present study shows that the Hb and LH exert synergistic action in the regulation of the cardiovascular activities.

Animals↗

PubMed1976

Dual localization of histamine in an ascending neuronal pathway and in non-neuronal cells evidenced by lesions in the lateral hypothalamic area.

The effects of lesions placed in the lateral hypothalamic area, i.e., interrupting the MFB (as evidenced by a 65% decrease in cortical noradrenaline and serotonin) suggest a pluricompartmentation of brain histamine (HA). The existence of an ascending histaminergic system is indicated by the reductions in l-histidine decarboxylase (H.D.) activity, in [3H]histamine synthesis and in HA content, in the cortex of lesioned rats. Moreover, the decrease in H.D. activity was restricted to the regions rostral to the lesion, without modification caudally. The time-course of the alterations in H.D. activity and in HA content is compatible with a process of anterograde degeneration. In subcellular fractionation studies, the reduction in cortical HA content was found to be mainly confined to the P2 fraction, which contains the synaptosomes. Although the widespread ipsilateral distribution of HA synthesizing terminals resembles that of monoaminergic ones, the absence of reduction in H.D. activity after selective destruction of catecholaminergic and serotoninergic neurons, by 6-hydroxydopamine or 5,6-dihydroxytryptamine respectively, renders likely the existence of specific HA-containing neurons. That the release of the amine from these neurons might be related to the nerve impulse flow is suggested by the transient effects of the lesions which preceded the degenerative process (elevated endogenous HA level and slowed rate of [3H]HA synthesis). In addition, the discrepancy between the reduction in H.D. activity and in HA level after the lesions could be explained by the presence of the amine in another neuronal system and/or in non-neuronal cells, not affected by the lesion. This additional compartment is characterized by a high HA content and a low H.D. activity and could therefore be localized in mast-cells. The respective sizes of these two compartments, estimated by several methods, appear to be approximately the same.

5-Hydroxytryptophan↗