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Results for “Hypothalamic Area, Lateral”

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PubMed1982

Mechanism of inhibition by the amygdala in the lateral hypothalamic area of rats.

The inhibition of neuronal activity in the lateral hypothalamus (LHA) of the rat by the basolateral nucleus of the amygdala (AL) was investigated by analyzing evoked potentials, single unit discharges and intracellular synaptic potentials. A single volley to the AL induced a negative-positive-wave in the LHA. The negative-wave threshold was lower than that of the positive wave. Analysis of depth profiles showed that the negative- and positive-waves appeared first at the dorsal margin of the LHA, peaked within the LHA, and were clearly different from each other. The effects of acute lesions showed the negative-wave to be conducted through the direct amygdalo-hypothalamic pathway. The positive-wave: through the stria terminalis. Stimulation of the stria terminalis produced positive evoked potentials with latencies shorter than those of the positive-waves. When conditioning and test stimuli were delivered to the AL, the negative-wave was inhibited for about 90 msec by the evoked positive-wave. Single AL stimuli evoked single unit discharges followed by inhibition of spontaneous firing for about 100 msec. Single stria terminalis stimuli inhibited spontaneous firing for the duration of the positive evoked potential. Intracellular LHA recording during single AL stimuli showed the presence of an EPSP followed by a 100 msec long lasting IPSP. The negative and positive extracellular potentials corresponded to these synaptic potentials. Inward current injection of 1 to 1.4 nA reversed the IPSP's indicating a -15 mV hyperpolarization difference between the IPSP reversal potential and the resting potential in LHA cells. The ionic mechanism of the IPSP is also discussed.

Amygdala↗
PubMed1985

Study of sodium and potassium excretion after renal denervation and cholinergic stimulation of the lateral hypothalamic area of the rat.

Studies were undertaken to characterize the renal responses to acute unilateral renal denervation and chronic bilateral denervated kidneys after cholinergic stimulation of the anterior part of the lateral hypothalamus. Denervation was produced in anesthetized and conscious nondiuretic rats by application of phenol to the renal artery. Studies were also performed in sham denervated rats. Whole kidney function in anesthetized animals showed a significant increase of fractional sodium excretion (0.7 +/- 0.1 to 1.7 +/- 0.4%, P less than 0.01) both in the denervated and in the innervated kidney (0.09 +/- 0.02 to 1.1 +/- 0.2%, P less than 0.005) after carbachol injection into the LHA, whereas the percentage of filtered potassium excreted increased only in the innervated kidney (11.4 +/- 1.3 to 16.3 +/- 1.1%, P less than 0.01). Similarly, in conscious rats, fractional sodium excretion increased after cholinergic stimulation in animals having denervated kidneys (2.1 +/- 0.1 vs 3.6 +/- 0.2%, P less than 0.005). Fractional potassium excretion also increased both in rats with sham-denervated and denervated kidney. There was an acute elevation in mean arterial blood pressure and glomerular filtration rate (GFR) during the first 20-min after carbachol injection. Sodium excretion was statistically significant during the three 20-min collections of the experimental period. This suggests that the natriuresis is not associated with increased arterial pressure, GFR or renal plasma flow. Our results indicate that natriuresis occurs even in the absence of the renal nerves.

Animals↗
PubMed1979

Distribution of retinal axons within the lateral hypothalamic area.

Intraocular injections of tritiated leucine were performed in normal and in unilaterally enucleated adult albino rats. Light microscopical evaluation of the autoradiograms revealed evidence for retinal afferents to distribute within a rather circumscribed area of the lateral hypothalamus. The silver grains were consistently, however, observed only in the group of enucleated animals, indicating differential transport under basic and experimental conditions.

Animals↗
PubMed1990

CNS projections to the pterygopalatine parasympathetic preganglionic neurons in the rat: a retrograde transneuronal viral cell body labeling study.

The retrograde transneuronal viral cell body labeling method was used to study the CNS nuclei that innervate the parasympathetic preganglionic neurons which project to the pterygopalatine ganglion. Small injections of a suspension of pseudorabies virus (PRV) were made in the pterygopalatine ganglion of rats and after 4 days their brains wer e processed for immunohistochemical detection of PRV. Some of the tissues were stained with a dual immunofluoresence method that permitted the visualization of PRV and neurotransmitter enzyme or serotonin immunoreactivity in the same cell. Retrograde cell body labeling was detected in the ipsilateral ventrolateral medulla oblongata in the region that has been termed the superior salivatory nucleus. This area was the same region that was retrogradely labeled after Fluoro-Gold dye injections in the pterygopalatine ganglion. Retrograde transneuronally infected cell bodies that provide putative afferent inputs to the pytergopalatine parasympathetic preganglionic neurons were mapped throughout the brain. In the medulla oblongata, transneuronally labeled neurons were seen in the nucleus tractus solitarii, dorsomedial part of the spinal trigeminal nucleus and gigantocellular reticular nucleus. In most experiments, some A1 catecholamine cells and serotonin neurons of the raphe magnus, raphe pallidus, raphe obscurus, and parapyramidal nuclei were labeled. In the pons, labeled cells were found in the parabrachial nucleus. A5 catecholamine cell group, and non-catecholamine part of the subcoeruleus region. In the midbrain, cell body labeling was located in the central gray matter and retrorubral field. In the diencephalon, labeling was found mainly in the hypothalamus. The areas included the lateral hypothalamic area, lateral preoptic area, dorsomedial and paraventricular hypothalamic nuclei, and ventral zona incerta. Contralateral second order cell body labeling was seen in the tuberomammillary nucleus of the hypothalamus. Some of these cells were histidine decarboxylase-immunoreactive. In the forebrain, the bed nucleus of the stria terminalis, substantia innominata, and an area of the cerebral cortex called the amygdalopiriform transition zone were labeled.

Animals↗
PubMedDate not supplied

Adrenergic projections from the lower brainstem to the hypothalamic paraventricular nucleus, the lateral hypothalamic area and the central nucleus of the amygdala in rats.

Fine networks of phenylethanolamine N-methyltransferase (PNMT)-immunoreactive fibers are found in the hypothalamic paraventricular nucleus--mainly in the anterior, dorsal and dorso-medial parvicellular subdivisions, the lateral hypothalamus (dorsal, lateral and ventral to the fornix) and in the central amygdaloid nucleus. Coronal hemisections of the brainstem through the rostral level of the medulla oblongata show that most hypothalamic and amygdaloid PNMT fibers arise from the medullary adrenergic cell groups. Fourteen, but not 10 days after total hemisections, PNMT fibers disappeared almost completely from the hypothalamus and amygdala, ipsilateral to the knife cuts. A small decrease was also observed in the ventral, lateral hypothalamus on the contralateral side. Partial depletion of PNMT-immunoreactivity in the hypothalamus and the amygdala after medial or lateral brainstem hemisections indicates that ascending PNMT-immunoreactive fibers pass through mainly the lateral portion of the medulla, but some fibers also in its medial portion. Midsagittal transection of the diencephalon slightly reduced PNMT immunostaining in the paraventricular nucleus and the lateral hypothalamus bilaterally. The results show that the ascending PNMT system essentially is ipsilateral, but probably with a small crossing-over component, both at the diencephalic and lower brainstem level.

Adrenergic Fibers↗
PubMed1995

Role of alpha 1 and alpha 2-adrenoceptors of the lateral hypothalamic area on urinary excretion caused by centrally administered angiotensin II.

To determine whether central alpha 1 and alpha 2-adrenergic mechanisms are involved in urinary sodium and potassium excretion and urine volume induced by angiotensin II (ANGII), these renal parameters were measured in volume-expanded Holtzman rats with cannulas implanted into lateral ventricle (LV) and lateral hypothalamus (LH). The injection of ANGII into LV in rats with volume expansion reduced the sodium, potassium and urine excretion in comparison to the control injections of isotonic saline, whereas prazosin (alpha 1 antagonist) potentiated these effects. Clonidine (alpha 2 agonist) and yohimbine (alpha 2 antagonist) injected into LH previous to injection of ANGII into LV also abolished the inhibitory effect of ANGII. These results suggest that the discharge of central alpha-adrenergic receptors has dual inhibitory and excitatory effect on antinatriuretic, antikaliuretic and antidiuretic effect induced by central ANGII in volume-expanded rats.

Angiotensin II↗
PubMed1995

Distribution of NMDAR1 receptor subunit mRNA and [125I]MK-801 binding in the hypothalamus of intact, castrate and castrate-DHTP treated male rats.

This study examines NMDAR1 receptor subunit mRNA expression and [125I]MK-801 binding in hypothalamic and limbic nuclei of intact, castrate and castrate-dihydrotestosterone propionate (DHTP)-treated male rats. In intact rats, the highest levels of NMDAR1 mRNA were observed in the supraoptic, suprachiasmatic, ventromedial and arcuate nuclei. Low levels of hybridization were observed in the bed nucleus of the stria terminalis, lateral preoptic area, lateral hypothalamic area and lateral septum. In castrated rats both NMDAR1 mRNA and [125I]MK-801 binding are significantly decreased in the lateral septum compared to castrate rats treated with DHTP, a non-aromatizable androgen. NMDAR1 mRNA was also significantly decreased in the supraoptic nucleus of castrate rats when compared to castrate rats treated with DHTP. These data suggest that androgens may modulate NMDA receptor function in some parts of the central nervous system.

Animals↗
PubMed1987

Coexistence of substance P- and enkephalin-like peptides in single neurons of the rat hypothalamus.

The distribution of substance P- and enkephalin-like immunoreactivity in single cells were examined by the double immunofluorescence method. Substance P- and leucine-enkephalin-like compounds coexisted within individual neurons of some hypothalamic areas such as the medial preoptic area, anterior hypothalamic area, perifornical area, lateral hypothalamic area, premammillary nuclei and posterior hypothalamic nucleus, although they did not coexist in the majority of immunoreactive cells.

Animals↗