Showing papers on "Hypothalamus published in 1988"

Interleukin-1 immunoreactive innervation of the human hypothalamus

Abstract: Interleukin-1 (IL-1) is a cytokine that mediates the acute phase reaction. Many of the actions of IL-1 involve direct effects on the central nervous system. However, IL-1 has not previously been identified as an intrinsic component within the brain, except in glial cells. An antiserum directed against human IL-1 beta was used to stain the human brain immunohistochemically for IL-1 beta-like immunoreactive neural elements. IL-1 beta-immunoreactive fibers were found innervating the key endocrine and autonomic cell groups that control the central components of the acute phase reaction. These results indicate that IL-1 may be an intrinsic neuromodulator in central nervous system pathways that mediate various metabolic functions of the acute phase reaction, including the body temperature changes that produce the febrile response.

Projections of the medial preoptic nucleus: a Phaseolus vulgaris leucoagglutinin anterograde tract-tracing study in the rat.

Abstract: The projections of the medial preoptic nucleus (MPN) were examined by making injections of the anterogradely transported lectin Phaseolus vulgaris leucoagglutinin (PHA-L) into the MPN and charting the distribution of labeled fibers. The evidence indicates that the MPN projects extensively to widely distributed regions in both the forebrain and brainstem, most of which also supply inputs to the nucleus. An important neuroendocrine role for the MPN is underscored by its extensive projections to almost all parts of the periventricular zone of the hypothalamus, including the anteroventral periventricular, anterior part of the periventricular, paraventricular (PVH), and arcuate nuclei, and a role in autonomic mechanisms is indicated by projections to such regions as the dorsal and lateral parvicellular parts of the PVH, the lateral parabrachial nucleus, and the nucleus of the solitary tract. Other projections of the MPN suggest participation in the initiation of specific motivated behaviors. For example, inputs to two nuclei of the medial zone of the hypothalamus, the ventromedial and dorsomedial nuclei, may be related to the control of reproductive and ingestive behaviors, respectively, although the possible functional significance of a strong projection to the ventral premammillary nucleus is presently unclear. The execution of these behaviors may involve activation of somatomotor regions via projections to the substantia innominata, zona incerta, ventral tegmental area, and pedunculopontine nucleus. Similarly, inputs to other regions that project directly to the spinal cord, such as the periaqueductal gray, the laterodorsal tegmental nucleus, certain medullary raphe nuclei, and the magnocellular reticular nucleus may also be involved in modulating somatic and/or autonomic reflexes. Finally, the MPN may influence a wide variety of physiological mechanisms and behaviors through its massive projections to areas like the ventral part of the lateral septal nucleus, the bed nucleus of the stria terminalis, the lateral hypothalamic area, the supramammillary nucleus, and the ventral tegmental area, all of which have extensive connections with regions along the medial forebrain bundle. Although the PHA-L method does not allow a clear demonstration of possible differential projections from each subdivision of the MPN, our results suggest that each of them does give rise to a unique pattern of outputs.(ABSTRACT TRUNCATED AT 400 WORDS)

Glucocorticoid stimulates expression of corticotropin-releasing hormone gene in human placenta

Abstract: Primary cultures of purified human cytotrophoblasts have been used to examine the expression of the corticotropin-releasing hormone (CRH) gene in placenta. We report here that glucocorticoids stimulate placental CRH synthesis and secretion in primary cultures of human placenta. This stimulation is in contrast to the glucocorticoid suppression of CRH expression in hypothalamus. The positive regulation of CRH by glucocorticoids suggests that the rise in CRH preceding parturition could result from the previously described rise in fetal glucocorticoids. Furthermore, this increase in placental CRH could stimulate, via adrenocorticotropic hormone, a further rise in fetal glucocorticoids, completing a positive feedback loop that would be terminated by delivery.

Neurochemical organization of the hypothalamic projection to the spinal cord in the rat.

Abstract: The hypothalamus provides a major projection to the spinal cord that innervates primarily lamina I of the dorsal horn and the sympathetic and parasympathetic preganglionic cell columns. We have examined the chemical organization of the neurons that contribute to this pathway by using combined retrograde transport of fluorescent dyes and immunohistochemistry for 15 different putative neurotransmitters or their synthetic enzymes. Our results demonstrate that 5 cytoarchitectonically distinct cell groups in the hypothalamus contribute to the spinal projection and that each has its own predominant chemical types. In the paraventricular nucleus, substantial numbers of hypothalamo-spinal neurons stain with antisera against arginine vasopressin (25-35%), oxytocin (20-25%), and metenkephalin (10%). About 25% of the neurons with spinal projections in the retrochiasmatic area stain with an antiserum against α-melanocyte-stimulating hormone. Nearly 100% of the hypothalamo-spinal neurons in the tuberal lateral hypothalamic area stain with this same antiserum, but these cells do not stain for other proopiomelanocortin-derived peptides, and so probably contain a cross-reacting peptide. This population must be distinguished from an adjacent cell group, in the perifornical region, where many spinal projection neurons stain with antisera against dynorphin (25%) or atrial natriuretic peptide (20%). Finally, in the dorsal hypothalamic area as many as 55-75% of the neurons with spinal projections are dopaminergic, on the basis of their staining with an antiserum against tyrosine hydroxylase. These 5 neurochemically distinct projections from the hypothalamus to the spinal cord are discussed in the context of their possible functional significance.

Textbook of Endocrine Physiology

Abstract: Contributors 1. Organization of the Endocrine System 2. Genes and Hormones 3. Mechanisms of Hormone Action 4. Assessment of Endocrine Function 5. The Anterior Pituitary and Hypothalamus 6. The Posterior Pituitary and Water Metabolism 7. Sexual Differentiation 8. Female Reproductive Function 9. Male Reproductive Function 10. Fertilization, Implantation, and Endocrinology of Pregnancy 11. Growth Regulation 12. The Thyroid 13. The Adrenal Glands 14. Calcium Homeostasis 15. Glucose, Lipid, and Protein Metabolism Index

The Role of Somatostatin in the Regulation of Anterior Pituitary Hormone Secretion and the Use of Its Analogs in the Treatment of Human Pituitary Tumors

Abstract: I. Introduction THE PRESENCE of GH-inhibitory substances in hypothalamic extracts was originally detected accidentally by Krulich et al. (1) during investigations into the distribution of GH-releasing factors throughout the rat hypothalamus. Several years later Brazeau et al. (2) isolated and characterized this somatotropin releaseinhibiting factor, called somatostatin (SRIF), which turned out to be a cyclic peptide consisting of 14 amino acids. SRIF was the first hormone to broaden the classic concepts of endocrinology because it has physiological effects both at the periphery and the central nervous system (3). Several reviews and proceedings from international symposia are available, which summarize the developments in the field of SRIF (4–12). In recent years SRIF analogs have been developed which can be used clinically. In the present review the physiological role of SRIF in the regulation of anterior pituitary function has been summarized as far as it contributes to the understanding of the use and ...

Efferent connections of the substantia innominata in the rat.

Abstract: The efferent connections of the substantia innominata (SI) were investigated employing the anterograde axonal transport of Phaseolus vulgaris leucoagglutinin (PHA-L) and the retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). The projections of the SI largely reciprocate the afferent connections described by Grove (J. Comp. Neurol. 277:315-346, '88) and thus further distinguish a dorsal and a ventral division in the SI. Efferents from both the dorsal and ventral divisions of the SI descend as far caudal as the ventral tegmental area, substantia nigra, and peripeduncular area, but projections to pontine and medullary structures appear to originate mainly from the dorsal SI. Within the amygdala and hypothalamus, which receive widespread innervation from the SI, the dorsal SI projects preferentially to the lateral part of the bed nucleus of the stria terminalis; the lateral, basolateral, and central nuclei of the amygdala; the lateral preoptic area; paraventricular nucleus of the hypothalamus; and certain parts of the lateral hypothalamus, prominently including the perifornical and caudolateral zones described previously. The ventral SI projects more heavily to the medial part of the bed nucleus of the stria terminalis; the anterior amygdaloid area; a ventromedial amygdaloid region that includes but is not limited to the medial nucleus; the lateral and medial preoptic areas; and the anterior hypothalamus. Modest projections reach the lateral hypothalamus, with at least a slight preference for the medial part of the region, and the ventromedial and arcuate hypothalamic nuclei. Both SI divisions appear to innervate the dorsomedial and posterior hypothalamus and the supramammillary region. In the thalamus, the subparafascicular, gustatory, and midline nuclei receive a light innervation from the SI, which projects more densely to the medial part of the mediodorsal nucleus and the reticular nucleus. Cortical efferents from at least the midrostrocaudal part of the SI are distributed primarily in piriform, infralimbic, prelimbic, anterior cingulate, granular and agranular insular, perirhinal, and entorhinal cortices as well as in the main and accessory olfactory bulbs. The cells of origin for many projections arising from the SI were identified as cholinergic or noncholinergic by combining the retrograde transport of WGA-HRP with histochemical and immunohistochemical procedures to demonstrate acetylcholinesterase activity or choline acetyltransferase immunoreactivity. Most of the descending efferents of the SI appear to arise primarily or exclusively from noncholinergic cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic Stress Increases Serotonin and Noradrenaline in Rat Brain and Sensitizes Their Responses to a Further Acute Stress

Abstract: The effects of 1 h/day restraint in plastic tubes for 24 days on the levels of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan (TP), and noradrenaline (NA) in six regions of rat brain 20 h after the last restraint period were investigated. The levels of 5-HT, 5-HIAA, and NA but not TP increased in several regions. The effects of 1 h of immobilization on both control and chronically restrained rats were also studied. Immobilization per se did not alter brain 5-HT, 5-HIAA, and TP levels, but decreased NA in the pons plus medulla oblongata and hypothalamus. However, immobilization after chronic restraint decreased 5-HT, increased 5-HIAA, and decreased NA in most brain regions in comparison with values for the chronically restrained rats. We suggest that chronic restraint leads to compensatory increases of brain 5-HT and NA synthesis and sensitizes both monoaminergic systems to an additional acute stress. These changes may affect coping with stress demands.

Corticotropin-releasing factor receptors and pituitary adrenal responses during immobilization stress

Abstract: The regulation of pituitary and brain CRF receptors and corticotroph responses during stress were studied in rats subjected to prolonged immobilization. Plasma ACTH levels showed the characteristic biphasic changes, with a rapid 23-fold increase in 15 min, followed by a decrease to about twice the basal levels after 6-h immobilization. In contrast, plasma corticosterone levels were markedly elevated throughout the duration of the stress. Pituitary CRF receptor content, measured by binding of [125I]Tyr-ovine CRF to pituitary membrane-rich fractions, was unchanged after 2.5 h, but was reduced by 28 ± 2.7% (±SE) and 47.6 ± 1.1% after 18 and 48 h of immobilization, respectively. These results were confirmed by autoradiography in slide-mounted frozen pituitary sections. In contrast, no changes in CRF receptor content were observed in brain areas, including olfactory bulb, frontoparietal cortex, hippocampus, amygdala, and lateral septum. A concomitant decrease in immunoreactive (ir) CRF content in the median em...

Corticotropin-releasing hormone.

Abstract: THAT both neural and hormonal changes play a part in the adaptive responses of complex organisms to physical or psychological challenges has been appreciated for well over a century. In 1948, Harris1 proposed that the hypothalamus served as the key link between the nervous and endocrine systems in reacting to the environment, and suggested that hypothalamic influences on the anterior pituitary were humorally transmitted. The first convincing reports of the existence of such a humoral substance followed soon thereafter, with the demonstrations in 1955 by Saffran et al.,2 using neurohypophysial extracts, and by Guillemin and Rosenberg,3 employing hypothalamic preparations, of . . .

Neuropeptide-Y and ACTH-immunoreactive innervation of corticotropin releasing factor (CRF)-synthesizing neurons in the hypothalamus of the rat. An immunocytochemical analysis at the light and electron microscopic levels.

Abstract: Corticotropin releasing factor (CRF), synthesized in neurons of the hypothalamic paraventricular nucleus (PVN), is one of the main regulators of the pituitaryadrenal cortex endocrine axis In order to elucidate the possible involvement of the central neuropeptide-Y (NPY)-and adrenocorticotroph hormone (ACTH)-immunoreactive (IR) systems in the innervation of hypophysiotrophic CRF-synthesizing neurons, immunocytochemical double labelling studies were conducted in the hypothalamus of the rat to localize CRF-synthesizing neurons, as well as neuronal fibers exhibiting NPY and ACTH-immunoreactivity, respectively The parvocellular subnuclei of the PVN received an intense NPY-and ACTH-IR innervation At the light microscopic level, these peptidergic axons were associated with the dendrites and perikarya of CRF-IR neurons Ultrastructural analysis revealed that NPY- and ACTH-IR axons established synaptic specializations with parvocellular neurons expressing CRF-immunoreactivity These findings indicate that both neuropeptide-Y and adrenocorticotroph hormone containing neuronal systems of the brain are capable of influencing adrenal function via synaptic interactions with hypophysiotrophic CRF-synthesizing neurons The data also support the concept that NPY and ACTH might be ntilized as neuromodulators within the PVN

Estrogen increases proenkephalin messenger ribonucleic acid levels in the ventromedial hypothalamus of the rat.

Abstract: The effects of estrogen on proenkephalin (PE) gene expression were measured in neurons of the ventromedial hypothalamus. Slot blot hybridization analysis indicates that the levels of PE mRNA in the ventromedial hypothalamus of ovariectomized rats increase 3.1-fold after 2 weeks of estrogen replacement. In situ hybridization reveals that the estrogeninducible enkephalinergic neurons are located in the ventrolateral aspect of the ventromedial nucleus, a subnucleus known to contain many estrogen-concentrating neurons. The increase in PE mRNA levels is due to both a 63% increase in the number of detectable PE mRNA-containing neurons and a 2.0-fold increase in the levels of PE mRNA per enkephalinergic neuron (1.63 × 2.0 = 3.3-fold overall induction). This estrogen-regulated enkephalinergic cell group may represent part of the neural network mediating estrogen's effects on reproductive behavior and/or other neuroendocrine processes.

Regulation of the messenger ribonucleic acid for corticotropin-releasing factor in the paraventricular nucleus and other brain sites of the rat

Abstract: CRF, from the paraventricular nucleus of the hypothalamus (PVN), is the major hypothalamic releasing factor that controls pituitary ACTH. Recently, the mRNA for CRF and the CRF peptide have been detected in other brain sites. However, there is little information on the function and regulation of CRF in brain sites outside the paraventricular nucleus. We investigated the content of CRF mRNA in the PVN, the central nucleus of the amygdala (CN), the bed nucleus of the stria terminalis (BN), and the supraoptic nucleus (SON). Northern gel analysis showed that the mRNA for CRF is present in the BN, CN, and SON as well as the PVN, and that all are the same size. In response to adrenalectomy, the level of hybridizable mRNA increased 2.75-fold over 7 days in the PVN; there was no change in the CN, BN, or SON. High dose dexamethasone decreased, but did not eliminate, the PVN CRF mRNA; it was without effect in the other sites. Glucocorticoid replacement with constant low blood levels of corticosterone (5.6 ± 0.3 μg/...

Vasopressin mRNA in the suprachiasmatic nuclei: daily regulation of polyadenylate tail length

Abstract: Daily variation has been found in the length of the polyadenylate tail attached to vasopressin messenger RNA in the suprachiasmatic nuclei, which is the location of an endogenous circadian pacemaker in mammals. No such variation was found in the supraoptic or paraventricular nuclei. This variation in the length of the polyadenylate tail may underlie the circadian rhythm of vasopressin peptide levels in cerebrospinal fluid and is a unique example of a daily rhythm in messenger RNA structure.

A regional study of sex differences in rat brain serotonin

Abstract: 1. Male and female rats were compared with respect to serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan, dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 3-methoxytyramine (3-MT) levels in five brain regions (brainstem, hypothalamus/preoptic area, corpora striata, limbic forebrain and cortex). Brain 5-HT synthesis rate was also studied in the two sexes. 2. There were no consistent gender differences in the dopaminergic system. 3. In contrast, the serotonergic system was more expressed in females: 5-HT levels were significantly higher in females than in males in the brainstem and limbic forebrain and tended to be so in the cortex. 5-HIAA levels were significantly higher in females in all five brain regions. The 5-HIAA/5-HT ratios were significantly higher in females in the hypothalamus/preoptic area and limbic forebrain and tended to be so in the striatum and cortex. Tryptophan concentrations were significantly higher in females in the brainstem, striatum and cortex. In no brain region were 5-HT, 5-HIAA or tryptophan levels higher in males. Following L-amino acid decarboxylase inhibition 5-hydroxytryptophan (5-HTP) accumulation was more pronounced in the female rat brain. 4. Taken together these results suggest that the brain 5-HT system has a higher potential in female than in male rats. This sex difference is not restricted to a specific region but seems to exist generally in the brain.

Stress-related changes in cerebral catecholamine and indoleamine metabolism: lack of effect of adrenalectomy and corticosterone.

Abstract: The concentrations of catecholamine and indoleamine metabolites were measured in intact and adrenalectomized mice to determine whether adrenal hormones mediate or modulate the stress-induced responses. Thirty minutes of footshock resulted in significant increases of the ratios of the dopamine (DA) catabolite, dihydroxyphenylacetic acid (DOPAC), to DA in prefrontal cortex, nucleus accumbens, striatum, hypothalamus, and brainstem, and of homovanillic (HVA)/DA ratios in nucleus accumbens, striatum, amygdala, and hypothalamus. Ratios of 3-methoxy-4-hydroxyphenylethyleneglycol to norepinephrine (NE) were also increased in prefrontal cortex, nucleus accumbens, septum, amygdala, hypothalamus, hippocampus, and brainstem. The concentration of NE was decreased in amygdala. 5-Hydroxyindoleacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT, serotonin) ratios and free tryptophan were also increased in every brain region. Very similar data were obtained from mice restrained for 30 min. Adrenalectomy resulted in increased HVA/DA ratios in prefrontal cortex and striatum, and 5-HIAA/5-HT in septum. The stress-related changes were largely similar in adrenalectomized mice. Significant interactions between adrenalectomy and footshock treatment occurred in prefrontal cortical DOPAC/DA and hypothalamic NE which was depleted only in adrenalectomized mice, suggesting tendencies for these measures to be more responsive in adrenalectomized mice. Corticosterone administration (0.5-2.0 mg/kg s.c.) which resulted in plasma concentrations in the physiological range did not alter the concentrations of the cerebral metabolites measured in any region. We conclude that adrenal hormones do not mediate cerebral catecholamine or indoleamine metabolism in stress, although adrenalectomy may affect HVA and 5-HIAA metabolism, and there was a tendency for catecholamines to be more sensitive to stress in adrenalectomized animals.