Immunocytochemical ultrastructural study of hypothalamic neurons containing corticotropin-releasing factor in normal and adrenalectomized rats

The neurons of the rat hypothalamus which secrete corticotropin-releasing factor were studied by using a pre-embedding immunocytochemical staining technique that improves both the penetration of immunoreagents within the tissue and the preservation of the ultrastructural morphology of labeled structures. Comparison was made between the subcellular location of corticotropin-releasing factor-41 in perikarya of the paraventricular nucleus and axons of the median eminence, both in intact and adrenalectomized animals either untreated or 24 h after the intracerebral injection of colchicine. Morphometric analysis of the numerical density and of the diameter of corticotropin-releasing factor immunoreactive neurosecretory granules in axons of the median eminence of rats not treated with colchicine, indicated that the main modifications induced by adrenalectomy concerned (1) the differential repartition of labeled granules within the preterminal and terminal axonal portions of the median eminence, and (2) the enlargement of the diameter of labeled granules contained in these axons (from 98 nm to 165 nm). In the hypothalamus of intact and adrenalectomized rats, colchicine treatment increased the number of corticotropin-releasing factor-immunoreactive granules in the neuronal perikarya and reduced their number in the axons, but both these variations were much more marked in adrenalectomized rats. Although the corticotropin-releasing factor immunoreactive granules that accumulated in the perikarya after colchicine treatment were slightly smaller than those in the corresponding axons, the diameter of perikaryal-labeled granules was larger in adrenalectomized than in intact animals (129 nm vs 93 nm). These findings fit the idea that adrenalectomy markedly stimulates both the synthesis and axonal excretion of secretory granules in the hypothalamic neurons secreting corticotropin-releasing factor. They also indicate that suppression of circulating corticosteroids induces qualitative modifications in these neurons leading to the visualization of larger neurosecretory granules, which may reflect differential synthesis and granular packing of synergistic peptides other than corticotropin-releasing factor and/or changes in the process of intragranular maturation of hormonal material.     

The influence of salt loading on vasopressin gene expression in magno- and parvocellular hypothalamic neurons: an immunocytochemical and in situ hybridization analysis

Arginine vasopressin peptide and messenger RNA expression were examined at the cellular level in the magnocellular and parvocellular neurons in the rat paraventricular nucleus after dehydration and rehydration, employing immunocytochemistry and in situ hybridization histochemistry on the same tissue sections. Most magnocellular vasopressinergic neurons of control animals expressed both vasopressin-like immunoreactivity and messenger RNA. However, neurons negative for vasopressin-like immunoreactivity but expressing messenger RNA were also detected, and their number increased during dehydration. In contrast, almost all of the parvocellular vasopressinergic neurons of dehydrated animals expressed vasopressin messenger RNA alone, with continued increase in their number after rehydration, despite return of the number of magnocellular vasopressinergic neurons to the control level. Vasopressin messenger RNA and corticotropin releasing factor-like immunoreactivity were co-localized in the same parvocellular neurons, and vasopressin-immunoreactive nerve terminals were detected in the external zone of the median eminence. These findings suggest that magno- and parvocellular vasopressinergic neurons are differentially activated during dehydration/rehydration. Osmotic stimuli activate all magnocellular vasopressinergic neurons, but the effect is not simultaneous in all of these neurons. Parvocellular vasopressinergic neurons are also activated by the stress of dehydration which effect appears to last longer than in the magnocellular system.     

Co-expression of vasopressin and androgen-binding protein in the rat hypothalamus

In previous studies we have observed the expression of androgen binding protein (ABP) in the rat hypothalamo-neurohypophysial system. With immunocytochemical double staining we found partial co-localization with oxytocin. In the present study we used antibodies to the anti-diuretic hormone arginine vasopressin (AVP) for co-localization with ABP in the rat hypothalamus. Both antigens were seen in the magnocellular paraventricular and supraoptic nuclei. Dense fiber networks with varicosities containing both AVP and ABP immunoreactivity were visible throughout the hypothalamus, the median eminence and in the posterior pituitary lobe. Double immunostaining revealed also co-existence in the parvocellular portion of the paraventricular nucleus and in the suprachiasmatic nucleus. ABP immunoreactive neurons in the preoptic region were devoid of AVP staining, AVP neurons in the bed nucleus of the stria terminalis stained only occasionally for ABP. We conclude that both the magnocellular and the parvocellular hypothalamic vasopressin systems are capable of expressing the steroid binding globulin, which is probably subject to axonal transport, along with the peptide hormone. Intrahypothalamic expression of ABP may be among the mechanisms necessary for rapid actions of steroids on hypothalamic neuroendocrine systems.     

Immunocytochemical detection of corticotropin-releasing factor: multiple cross-reactions of a widely used carboxy-terminally directed corticotropin-releasing factor antiserum (code rC70) in rat hypothalamus

Forty-one-residue corticotropin-releasing factor is a physiologically significant mediator of the hypothalamic control of corticotropin secretion by the anterior pituitary gland. This releasing hormone is produced by parvicellular neurons in the hypothalamic paraventricular nucleus that project to the external zone of the median eminence. Recent immunocytochemical evidence based on work with a rabbit antiserum against rat corticotropin-releasing factor (code rC70) suggests that about half of the parvicellular corticotropin-releasing factor-containing neurons in the hypothalamic paraventricular nucleus synthesize vasopressin, another potent corticotropin secretagogue, while the rest of the cells do not. If this is indeed the case, the neurohumoral control of corticotropin release may be mediated via distinct hypothalamic effector pathways utilizing releasing hormone cocktails of varying composition. In the present study we have examined the specificity of various antisera against rat corticotropin-releasing factor in immunocytochemical staining. Male Wistar rats pretreated with colchicine were used throughout. The brain was fixed by perfusion with a Zamboni type fixative solution. Vibratome sections of the hypothalamus were immunostained with three different primary antisera (codes rC70, rCRF-3, oCRF-N) using the peroxidase-antiperoxidase or avidin-biotin complex methods. All three antisera stained cell groups previously described to be immunopositive for corticotropin-releasing factor. Most notably, however, rC70 labelled a significant number of additional cells, most readily identified in the arcuate and suprachiasmatic nuclei, as well as in the dorsolateral hypothalamic area caudal to the paraventricular nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vasoactive intestinal polypeptide/peptide histidine isoleucine immunoreactive neuron systems in the basal hypothalamus of the rat with special reference to the portal vasculature: an immunohistochemical and in situ hybridization study

Using immunohistochemistry and in situ hybridization, we have analysed the distribution of vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI) in hypothalamus of male and female Sprague-Dawley rats under normal and experimental conditions. In most cases there was a good overlap between the distribution of VIP- and PHI-immunoreactive structures. At the median eminence level precapillary arterioles along its lateral aspect were surrounded by dense networks of VIP/PHI-positive fibers, suggesting that these peptides, via their vasodilatory property, may be involved in control of blood flow through portal vessels. Furthermore, a thick VIP/PHI-containing nerve bundle of variable size was observed on the surface of the median eminence in coronal, horizontal and sagittal sections. Also this bundle could be of importance for portal circulation, but VIP/PHI released may reach the anterior pituitary level and play a role in, for example, control of prolactin release. Although different lesions were performed, the origin of the VIP/PHI nerves around lateral blood arterioles and of the bundle is still unclear, but is in all probability peripheral. Within the median eminence of untreated rats only few positive nerve endings were seen in the external layer, but after 48 h hypophysectomy a large number of PHI-immunoreactive fibers could be observed. With regard to cell bodies the suprachiasmatic nucleus contained VIP/PHI-immunoreactive neurons even in untreated rats. After colchicine administration fluorescent cells were in addition seen in several other hypothalamic nuclei, including the parvocellular paraventricular nucleus. After hypophysectomy, with in situ hybridization, VIP mRNA could be demonstrated in magno- and parvocellular neurons of the paraventricular nucleus, whereas in control rats VIP mRNA was undetectable. These results demonstrate that VIP/PHI are present in at least three systems of direct neuroendocrine importance: (1) in nerves related to the blood vessels in the median eminence and presumably involved in control of blood flow through the portal system; (2) in parvocellular paraventricular neurons, presumably related to stress-induced prolactin release; and (3) in magnocellular neurons after certain experimental manipulations.     

Coexistence of salusin and vasopressin in the rat hypothalamo-hypophyseal system

Salusins are two newly discovered TOR-related peptides consisting of 28 and 20 amino acids and designated salusin-alpha and salusin-beta, respectively. Using immunohistochemistry techniques, salusin-like immunoreactivity was detected in the rat hypothalamo-neurohypophyseal tract and immunopositive cells were distributed in the suprachiasmatic, supraoptic and paraventricular nucleus. In the paraventricular nucleus, salusin-like immunoreactivity was observed both in parvocellular and magnocellular neurons. Many salusin-positive nerve fibers and their terminals were identified in the internal layer of the median eminence and posterior pituitary. Less intense salusin-positive staining of fibers and terminals was found in the suprachiasmatic nucleus and external layer of the median eminence. Dual immunostaining was performed to determine if salusin coexisted with vasopressin or oxytocin in the hypothalamus. Most of the salusin-like immunoreactivity was detected in vasopressin- but not in oxytocin-containing neurons in these nuclei. The functional significance of the coexistence of salusin with vasopressin is discussed, including the possibility that salusin participates in the regulation of blood pressure.     

GABAergic innervation of corticotropin-releasing hormone (CRH)-secreting parvocellular neurons and its plasticity as demonstrated by quantitative immunoelectron microscopy

GABA has been identified as an important neurotransmitter in stress-related circuitry mediating inhibitory effects on neurosecretory neurons that comprise the central limb of the hypothalamo-pituitary-adrenocortical axis. Using combinations of pre-embedding immunostaining and postembedding immunogold methods at the ultrastructural level, direct synaptic contacts were revealed between GABA-containing terminals and neurosecretory cells that were immunoreactive for corticotropin-releasing hormone (CRH) in the hypothalamic paraventricular nucleus (PVN). The vast majority of axo-dendritic GABA synapses was symmetric (inhibitory) type, and 46% of all synaptic boutons in the medial parvocellular subdivision of the PVN were immunoreactive to GABA. Using the disector method, an unbiased stereological method on serial ultrathin sections, the total calculated number of synaptic contacts within the medial parvocellular subdivision of the PVN was 55.4 x 10(6)/mm(3). On CRH-positive profiles 20.1 x 10(6) GABAergic synaptic boutons were detected per mm(3) in control, colchicine-treated rats. In the medial parvocellular subdivision, 79% of GABAergic boutons terminated on CRH neurons. Following adrenalectomy, which increases the synthetic and secretory activities of CRH neurons, the number of GABAergic synapses that terminate on CRH-positive profiles was increased by 55%. GABA-containing boutons appeared to be swollen, while the contact surfaces of cellular membranes between GABAergic boutons and CRH-positive profiles were shorter in adrenalectomized animals than in controls.Our data provide ultrastructural evidence for direct inhibitory GABAergic control of stress-related CRH neurons and suggest a pivotal role of GABA-containing inputs in the functional plasticity of parvocellular neurosecretory neurons seen in response to adrenalectomy.     

Vasopressin and inflammation

At least three vasopressinergic brain systems are involved in inflammatory reaction. The first one is VP neurons of the bed nucleus of stria terminalis, projecting to antipyretic center in the preoptic forebrain region. The second system is neurons of the parvocellular subnucleus of the hypothalmic paraventricular nucleus. VP from these neurons reaches portal blood through the external zone of the median eminence. VP potentiates the effect of corticotropin releasing hormone on ACTH cells in the anterior pituitary. Synergetic modulation of pituitary-adrenal axis by these neurohormones maintains synthesis and release of glucocorticosteroids. The latter plays crucial role as endogenous immunosuppresants. The third VP system is magnocellular hypothalamic neurons that release vasopressin into general circulation. Systemic VP is capable of compensating the water lost caused by symptoms of inflammation. The review is devoted to analysis of current information concerning physiology and interactions between these systems during acute and chronic inflammation. The special reference has been made on the magnocellular neurons and the role of circulating vasopressin in the renal function regulation.     

针刺“足三里”穴下丘脑血管加压素(Vp)样细胞的形态学变化——免疫组织化学法

采用免疫组化PAP技术,在电针大鼠“足三里”穴位后,观察丘脑下部Vp样神经元的变化。发现视上核与室旁核Vp样大神经元数目增多、胞体胀大,并伸出细长突起。室旁核少数串珠状神经纤维可插入第三脑室壁的细胞之间。在视交叉上核腹内侧Vp小神经元密集,而背外侧反应阳性神经元较少。视上核与室旁核间的神经元岛的细胞体积增大、轴索变长伸向视上区。该区的串珠状纤维集合成束达正中隆起的外层。以上实验结果提示,电针“足三里”可促进下丘脑有关核团Vp样物质的合成与分泌。     

Light stimulation of the hypothalamic neuroendocrine system.

This paper demonstrates that, in the mediation of light, the suprachiasmatic nucleus (SCN) functionally associates with the anterior periventricular and parvocellular paraventricular neuron systems in rats. Intact rats (group 1) and rats undergoing a hemicomplete cutting of the SCN (group 2) were housed in a dark room (2-3 weeks) and killed after an exposure to light for 10, 30 or 60 min. Other intact animals (group 3) kept in a dark room (2 weeks) were exposed to light for 10 min, then stored 60 min in the dark room, and killed in darkness. The SCN, anterior periventricular nucleus, and parvocellular paraventricular nucleus were examined immunohistochemically using antisera for vasoactive intestinal polypeptide (VIP), arginine vasopressin, somatostatin, rat corticotropin releasing factor (rCRF), and c-fos protein. In comparison with animals kept in darkness, animals exposed for 10 and 30 min to light indicated a remarkable reduction of VIP immunoreactivity in the SCN and some increase of CRF immunoreactivity in the parvocellular paraventricular nucleus. The diminution of VIP immunoreactivity did not occur in the isolated SCN of group 2 animals. In group 3, a 10 min-light exposure induced a remarkable enhancement of nuclear c-fos immunoreactivity in neurons in the ventrolateral region of the SCN, in the anterior periventricular nucleus, and in the parvocellular paraventricular nucleus, most strongly in the SCN. Double immunolabeling methods have shown that VIP, somatostatin, and CRF neurons in the respective nuclei were c-fos positive.     

Effect of adrenalectomy on miniature inhibitory postsynaptic currents in the paraventricular nucleus of the hypothalamus

Within the rat paraventricular nucleus of the hypothalamus two types of neurons have been distinguished based on morphological appearance, i.e., parvocellular and magnocellular neurons. The parvocellular neurons play a key role in regulating the activity of the hypothalamo-pituitary-adrenal axis, which is activated, e.g., after stress exposure. These neurons receive humoral negative feedback via the adrenal hormone corticosterone but also neuronal inhibitory input, either directly or transsynaptically relayed via GABAergic interneurons. In the present study we examined to what extent the neuronal GABAergic input is influenced by the humoral signal. To this end, miniature inhibitory postsynaptic currents (mIPSCs) were recorded in parvo- and magnocellular neurons of adrenalectomized rats, which lack corticosterone, and in sham-operated controls. Under visual control neurons in coronal slices containing the paraventricular nucleus were designated as putative parvocellular or magnocellular neurons: the former were located in the medial part of the nucleus and displayed a small fusiform soma; the latter were mostly located in the lateral part and were recognized by their large round soma. Compared with putative magnocellular neurons, parvocellular neurons generally exhibited a lower membrane capacitance, lower mIPSC frequency, and smaller mIPSC amplitude. Following adrenalectomy, the mIPSC frequency was significantly enhanced in parvo- but not magnocellular neurons. Other properties of the cells were not affected. In a second series of experiments we examined whether the increase in mIPSC frequency was due to the absence of corticosterone or caused by other effects related to adrenalectomy. The data support the former explanation since implantation of a corticosterone releasing pellet after adrenalectomy fully prevented the change in mIPSC frequency. We conclude that, in the absence of humoral negative feedback, local GABAergic input of parvocellular neurons in the paraventricular nucleus is enhanced. This may provide a compensatory mechanism necessary for maintaining controllable network activity.     

Immunocytochemical localization of corticotropin-releasing factor (CRF) in the rat brain

The immunocytochemical localization of neurons containing the 41 amino acid peptide corticotropin-releasing factor (CRF) in the rat brain is described. The detection of CRF-like immunoreactivity in neurons was facilitated by colchicine pretreatment of the rats and by silver intensification of the diaminobenzidine end-product. The presence of immunoreactive CRF in perikarya, neuronal processes, and terminals in all major subdivisions of the rat brain is demonstrated. Aggregates of CRF-immunoreactive perikarya are found in the paraventricular, supraoptic, medial and periventricular preoptic, and premammillary nuclei of the hypothalamus, the bed nuclei of the stria terminalis and of the anterior commissure, the medial septal nucleus, the nucleus accumbens, the central amygdaloid nucleus, the olfactory bulb, the locus ceruleus, the parabrachial nucleus, the superior and inferior colliculus, and the medial vestibular nucleus. A few scattered perikarya with CRF-like immunoreactivity are present along the paraventriculo-infundibular pathway, in the anterior hypothalamus, the cerebral cortex, the hippocampus, and the periaqueductal gray of the mesencephalon and pons. Processes with CRF-like immunoreactivity are present in all of the above areas as well as in the cerebellum. The densest accumulation of CRF-immunoreactive terminals is seen in the external zone of the median eminence, with some immunoreactive CRF also present in the internal zone. The widespread but selective distribution of neurons containing CRF-like immunoreactivity supports the neuroendocrine role of this peptide and suggests that CRF, similarly to other neuropeptides, may also function as a neuromodulator throughout the brain.     

Application of avidin-biotinized peroxidase (ABC) method for immunocytochemical localization of corticotropin-releasing factor (CRF) in rat hypothalamus

Studies on immunocytochemical localization of corticotropin-releasing factor (CRF) were performed in the rat hypothalamus using avidin-biotinized peroxidase (ABC) and PAP techniques. In intact and control animals CRF-immunoreactive nerve fibers were observed within outer layer of median eminence. In the adrenalectomized animals, CRF was also demonstrated in perikarya of neurocytes and in their projections in paraventricular nucleus of the hypothalamus. In both immunocytochemical techniques identical localization of CRF was obtained. However, reaction intensity was greater with the ABC technique than with the PAP one. In bilateral adrenalectomized animals, a greater number of CRF-immunoreactive neural fibers were observed in the median eminence than in control rats and rats subjected to sham operation.     

Hypo-osmolarity stimulates and high sodium concentration inhibits thyrotropin-releasing hormone secretion from rat hypothalamus.

The hypothalamic paraventricular nucleus, representing cell bodies in which thyrotropin-releasing hormone is synthesized, and the median eminence, representing nerve terminals, were incubated in vitro. Various hypo- and hyperosmotic solutions were tested to determine osmotic sensitivity of thyrotropin-releasing hormone secretion. High KCl (56 mM) causing membrane depolarization was used as a non-specific control stimulus to induce thyrotropin-releasing hormone secretion. A 30% decrease of medium osmolarity (from 288 to 202 mOsmol/l) increased thyrotropin-releasing hormone secretion from both the paraventricular nucleus and median eminence. A 30% decrease of medium NaCl content by its replacement with choline chloride did not affect basal thyrotropin-releasing hormone secretion. Increasing medium osmolarity with biologically inactive L-glucose did not affect basal or KCl-induced thyrotropin-releasing hormone secretion from either structure. Medium made hyperosmotic (350-450 mOsmol/l) by increasing the NaCl concentration resulted in a dose-dependent decrease of basal thyrotropin-releasing hormone secretion and abolished KCl-induced thyrotropin-releasing hormone secretion. If an osmotically equivalent amount of choline chloride was substituted for NaCl, there was no effect on thyrotropin-releasing hormone secretion, indicating a specific action of Na+. This study indicates a specific sensitivity to high concentrations of Na+ ions of both thyrotropin-releasing hormone-producing parvocellular paraventricular neurons and thyrotropin-releasing hormone-containing nerve terminals in the median eminence.     

后叶加压素在下丘脑的分布和释放途径及失水对正中隆起中后叶加压素的影响

我们用免疫细胞化学方法(ICC)对大白鼠下丘脑中加压素(VP)免疫反应阳性的神经元作了较详细研究。观察到VP阳性神经元存在于下丘脑室旁核(PVN)各亚核、视上核(SON)、交叉上核(SCN)、室周核(PN)及一些附属核团,包括环状核(CN)、交叉后核(RCN)、下丘脑外侧核(HLN)、穹窿周围核(PFN)。且发现一特殊的VP阳性胞体聚集区—很可能是多巴胺神经元聚集区A_(14)中的细胞,位于第三脑室侧壁中1/3段两侧,腹内侧核背侧。本文首次观察到在PVN和SON之间有VP阳性的神经纤维相联系。ICC和免疫电镜研究进一步证明在正中隆起外带存在VP阳性纤维,含大颗粒囊泡的VP末梢紧邻门脉毛细血管。将HRP注入第四脑室用HRP逆行追踪与ICC方法相结合,在PVN中观察到双标细胞,与直接用ICC法所见VP阳性轴突伸入第三脑室腔的结果一致。说明PVN中存在接触脑脊液神经元。干渴动物正中隆起的内、外带中的VP免疫反应明显减弱。     

Time-dependent sensitization of corticotropin-releasing hormone, arginine vasopressin and c-fos immunoreactivity within the mouse brain in response to tumor necrosis factor-alpha

Stressor or cytokine treatments, such as interleukin-1beta, promote time-dependent alterations of hypothalamic-pituitary-adrenal functioning, including increased arginine vasopressin stores within corticotropin-releasing hormone (CRH) terminals in the external zone of the median eminence. Likewise, we have previously shown that the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), provoked a time-dependent sensitization of neuroendocrine and brain monoamine activity. To further explore the protracted consequences of TNF-alpha, the present investigation determined whether the cytokine sensitized activity of neuroendocrine regulatory brain regions, as assessed by c-fos expression, and had protracted consequences on amygdaloid CRH, as well as hypothalamic corticotropin secretagogues. Indeed, immunoreactivity for arginine vasopressin and corticotropin-releasing hormone, and their colocalization within cell terminals of the median eminence, varied over time following an initial 4.0-microg tumor necrosis factor-alpha treatment, peaking after 7 days and normalizing within 28 days. Within the central amygdala, a sensitization effect was evident as reflected by increased CRH immunoreactivity, but this effect required re-exposure to the cytokine, unlike the median eminence changes that simply evolved with the passage of time. As well, tumor necrosis factor-alpha provoked a marked sensitization of c-fos staining within the paraventricular nucleus of the hypothalamus, supraoptic nucleus and the central amygdala.From these data we suggest that tumor necrosis factor-alpha influences responsivity of stressor-reactive brain regions and has protracted effects on central neuropeptide expression within the hypothalamus and central amygdala, although the time course for the effects vary across brain regions. Evidently, exposure to tumor necrosis factor-alpha may promote neuroplasticity of brain circuits involved in mediating neuroendocrine, sickness or inflammatory responses. It is suggested that such a sensitization may influence the response to immunological and traumatic insults and may thus be relevant to behavioral pathology.     

Analysis of peptide histidine-isoleucine/vasoactive intestinal polypeptide-immunoreactive neurons in the central nervous system with special reference to their relation to corticotropin releasing factor- and enkephalin-like immunoreactivities in the paraventricular hypothalamic nucleus

The distribution of peptide histidine-isoleucine (PHI) and vasoactive intestinal polypeptide (VIP), two peptides derived from the same precursor molecule, was analysed with immunohistochemistry in the central nervous system of the rat, and to a limited extent in some other species including sheep, monkey and man. Special attention was focused on possible cross-reactivity between PHI antisera and corticotropin releasing factor in parvocellular neurons in the hypothalamic paraventricular nucleus projecting to the external layer of the median eminence. (1) Characterization of the PHI and VIP antisera revealed that they recognized different sequences of the peptide molecules. One of the PHI antisera (PHI-N), although mainly N-terminally directed, also probably contained an antibody population directed against the C-terminal amino acid in PHI which is an amidated isoleucine. Rat and human corticotropin releasing factor but not ovine also have an amidated isoleucine in C-terminal position. (2) PHI- and VIP-like immunoreactivity were found with parallel and overlapping distribution in all areas investigated in the rat central nervous system. In many cases coexistence of the two immunoreactivities could be directly demonstrated. PHI neurons were found in some areas so far not know to contain PHI/VIP neurons, including the dorsal septum, the septofimbrial nucleus, the stria terminalis and lamina V of the spinal cord. (3) Using an antiserum directed against the amino acid sequence 111-122 of the VIP/PHI precursor, immunoreactive cell bodies were seen in some areas containing VIP and PHI neurons. PHI- and VIP-like immunoreactivity were expressed in parallel in increasing amounts in the superficial laminae of the dorsal horn after transection of the sciatic nerve [G. P. McGregor et al. (1984) Neuroscience 13, 207-216; S. A. S. Shehab and M. E. Atkinson (1984) J. Anat. 139, 725; S. A. S. Shehab and M. E. Atkinson (1986) Expl Brain Res. 62, 422-430]. (5) The PHI-N antiserum stains large numbers of immunoreactive cells in the parvocellular part of the paraventricular nucleus and these cells are mostly identical with corticotropin releasing factor-positive neurons. Absorption experiments suggested that this PHI-N-like immunoreactivity to a large extent represented cross-reactivity with rat CRF and that earlier demonstration of many PHI-positive neurons in the paraventricular nucleus probably represents an artefact as proposed by F. Berkenbosch et al. (Neuroendocrinology 44, 338-346). However, some cells did, in fact, contain VIP- as well as PHI-like immunoreactivity as was shown with antisera not cross-reacting with corticotropin releasing factor.(ABSTRACT TRUNCATED AT 400 WORDS)     

Increase of thyrotropin-releasing hormone immunoreactivity in the nucleus of the solitary tract following bilateral lesions of the hypothalamic paraventricular nuclei

The effects of bilateral electrolytic lesions of hypothalamic paraventricular nucleus on thyrotropin-releasing hormone (TRH)-immunoreactive fibers of the nucleus of the solitary tract were studied by both immunocytochemistry and radioimmunoassay. Contrasting with a near disappearance of TRH immunoreactivity in the median eminence, both morphological and biochemical approaches demonstrate that such hypothalamic lesions induced significant increase of TRH immunoreactivity in the nucleus of solitary tract. These results confirm that TRH fibers of the nucleus of the solitary tract do not originate in the hypothalamic paraventricular nucleus (PVN). They further indicate that these TRH neurons projecting to the nucleus of the solitary tract are strongly influenced by neurons located within the PVN area.     

强啡肽B免疫反应阳性神经元在大鼠下丘脑的分布及与精氨酸加压素的共存

实验应用免疫细胞化学 PAP法显示了强啡肽 B免疫活性阳性神经元在大鼠下丘脑形态特征和分布特点。结果表明 :强啡肽 B正常条件下免疫活性阳性神经元仅在下丘脑的视上核、室旁核、环核、附属神经分泌核和室管膜。正中隆起处有强啡肽 B免疫活性阳性纤维分布。侧脑室注射秋水仙素后在下丘脑视前区、前区、室周核、前连合核、交叉上核、交叉后核、弓状核、背侧区、背内侧核、穹隆周核、下丘脑外侧区、腹内侧核、室周大细胞区等核区显示了强啡肽 B免疫活性阳性神经元。双标记免疫组织化学方法还显示强啡肽 B与精氨酸加压素主要共存于下丘脑室旁核 ,次为视上核 ,附属神经分泌核和下丘脑外侧区     

Effect of the glucocorticoid milieu on the immunostaining of peptide histidine isoleucine (PHI) in the rat hypothalamus

Effects of adrenalectomy (ADX) or dexamethasone (DEX) treatment on the immunostaining of hypothalamic peptide histidine isoleucine (PHI) were examined in male rats. After colchicine treatment, PHI-containing cell bodies were observed in the suprachiasmatic nucleus (SCN) and the parvocellular division of the paraventricular nucleus (PVN). ADX increased and DEX dose-dependently decreased the number of PHI-immunopositive neurons in the PVN. The number of SCN-PHI neurons was not affected by any treatment employed in this study. These results suggest that PVN-PHI neurons are under the effects of the glucocorticoid milieu, and that the neurons may be involved in the glucocorticoid regulation of adrenocorticotropin and prolactin secretion.