Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study continues a previous investigation on the median eminence (EM) (Krisch et al., 1978). In rats with high levels of neurohormones (LHRH, vasopressin) a limited immunohistochemical labeling of perivascular tanycyte processes can be observed surrounding capillaries in the marginal region of the organum vasculosum laminae terminalis (OVLT) and in the inner part of the subfornical organ (SFO). This labeling extends from the perivascular space a short distance along the tanycyte processes. By conventional electron microscopy and by freeze-etching, tight junctions are demonstrated at a distance from the capillary lumen which corresponds to the borderline of the immunohistochemical labeling of perivascular tanycyte processes in light microscopic preparations. The tight junctions are arranged in several parallel and helical rows and correspond to those found in the median eminence. Consequently, the immunohistochemical labeling the OVLT and in the SFO marks the intercellular cleft. In the circumventricular organs the immunostaining labels the extension of the perivascular space characterized by the hemal milieu. The perivascular space is separated off by tight junctions from the CSF-milieu of the adjacent neuropil. Furthermore, the present study demonstrates tight junctions in the marginal region of the area postrema (AP) between the perivascular processes of the tanycytes.
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PMID:The functional and structural border between the CSF- and blood-milieu in the circumventricular organs (organum vasculosum laminae terminalis, subfornical organ, area postrema) of the rat. 36 50

The reaction products of plasma enzyme degradation of TRH were identified by thin layer chromatography. The enzyme in normal rat plasma yields proline and pGlu-His as major reaction products. High concentrations of proline decrease peptide cleavage, resulting in greater amounts of acid TRH. The apparent Km of the enzyme is 4.1 X 10(-6) M. LHRH and neurotensin are competitive inhibitors with Ki of 5 X 10(-6) M and 1.5 X 10(-5) M, respectively. Somatostatin, MIF, oxytocin, arg-vasopressin, arg-vasotocin, neurophysin II and glucagon do not compete; and pGlu-His-Pro-OH, Glu-His-Pro-OH, pGlu-His, His-Pro-NH2, and Pro-NH2 do not affect enzyme activity. These data suggest that the substrated requires pGlu and a terminal or internal amide to complex with the enzyme. The enzyme is markedly inhibited by Cu++, Bal, benzamadine, p-(chloromercuri)-benzoic acid, moderately affected by EDTA and puromycin, and unaffected by mercaptoethanol. TSH does not affect enzyme activity while LH inhibits it moderately at high concentrations (300-600 pg/ml).
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PMID:Characteristics of the plasma TRH-degrading enzyme. 81 19

Immunoperoxidase technique and light microscopy have been used to localize neurosecretory systems for vasopressin, oxytocin and related neurophysins (neurohypophysial peptides)) and gonadotropin-releasing hormone (Gn-RH) in the rhesus monkey brain. All the neurohypophysial peptides were found in the magnocellular nuclei (suproptic and paraventricular) of the hypothalamus and in their projections to the posterior pituitary gland, the zona externa of the median eminence and the organum vasculosum of the lamina terminalis (OVLT). Gn-RH was found in smaller cell bodies which were widely scattered in the hypothalamus. Some of these were found in the media-basal hypothalamus in the infundibular nucleus and lateral and dorsal to it, while others were found in dorsal hypothalamus. Numerous cells were also located in the preoptic area close to the OLVT. Gn-RH-containing fibers projected to the OVLT and the zona externa of the median eminence. The two neurosecretory systems studied have two common features: magnocellular perikarya containing the neurohypophysial peptides and smaller elements containing Gn-RH are found near and appear to terminate around the fine vessels of the OVLT. In addition, cells of both systems send fibers to the hypophysial portal capillary system in the zona externa of the median eminence. Many more vasopressin-than oxytocin-containing fibers end in the entire expanse of the zona externa, where they are mainly concentrated in the anterior and middle parts, while Gn-RH fibers project to all portions.
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PMID:Organization of the hypothalamic-pituitary system: current concepts from immunohistochemical studies. 82 99

The effect of toluene on the hypothalamic hormone-secreting neurons and neurotransmitter-containing fibers in the rat was investigated by immunohistochemical methods. Multiple intraperitoneal injections of toluene (totally 7.5 ml) led to significant decreases of the neuronal numbers of vasopressin, oxytocin and neuropeptide Y in the preoptic and hypothalamic areas. The densities of vasopressin, oxytocin, norepinephrine and neuropeptide Y immunoreactive fibers of the toluene dose group decreased markedly in the median eminence. In contrast, LHRH neurons remained unchanged.
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PMID:Effects of toluene on the morphology of neuropeptide secretory neurons of the rat hypothalamus. 130 69

Tissue transplantation aided in formulating the neurohumoral hypothesis of anterior pituitary function. The concept of a hypophysiotropic region within the hypothalamus stemmed from experiments in which pituitary tissue was transplanted into the brain. Restoration of aberrant function of the central nervous system by transplants has been reported in two neuroendocrine models: the antidiuretic hormone-deficient Brattleboro rat and the gonadotropin-releasing hormone-deficient hypogonadal mouse. Neural transplants into the Brattleboro rat result in the survival of axons containing antidiuretic hormone but reversal of the physiological defect has not been confirmed. In the hypogonadal mouse grafts of preoptic area tissue into the third ventricle have restored pituitary hormone synthesis and secretion and gonadal activity, leading to nearly normal reproductive function. The gonadotropin-releasing hormone axons specifically innervate the median eminence of the hypothalamus, their normal target, which raises interesting questions of neurobiological graft/host interactions. The hpg model has been used to investigate factors affecting graft survival; by suitable immunosuppression it has been possible to reverse the hypogonadism with grafts of rat preoptic area tissue. Perhaps the most dramatic recent development has been the restoration of circadian rhythmicity to suprachiasmatic nucleus-lesioned hamsters by grafts of similar tissue. The rhythmicity restored is typical of the donor tissue.
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PMID:Hypothalamic transplantation. 142 28

Tritiated arginine-vasopressin (AVP), desglycinamide-vasopressin (DGAVP), chicken gonadotropin releasing hormone (GnRH) or carbetocin were injected intracarotidally into rats exposed to a restraint stress for 60 min. The peptide accumulations were determined in 9-13 brain regions and anterior pituitary. In separate experiments the cerebral blood flow was measured. The blood supply to the brain was decreased in stressed animals as indicated by: 1. significant decrease (17-50%) of cerebral blood flow; 2. diminished accumulation of tritiated AVP in the regions lacking a blood-brain barrier (BBB). Consequently, the values of peptide accumulation were corrected for the changed blood supply. Compared with control animals, restraint stress induced a higher accumulation of AVP (+41%), DGAVP (+60%), carbetocin (+81%) and GnRH (+104%).
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PMID:On the blood-brain barrier to peptides: effects of immobilization stress on regional blood supply and accumulation of labelled peptides in the rat brain. 147 92

Pituitaries of the African catfish, Clarias gariepinus, were prefixed in aldehyde fixatives, frozen in liquid propane and submitted to a cryosubstitution procedure. Ultrathin sections of the Lowicryl HM20-embedded tissue were treated with primary antisera raised in rabbits to gonadotropin releasing hormone (GnRH), vasopressin or gamma amino butyric acid (GABA) respectively. Binding of the primary antisera was visualized with goat anti-rabbit (GAR) labeled with gold. The general morphology of the tissue components in the cryosubstituted pituitaries matches with that obtained after routine embedding procedures. In addition, a strong labeling intensity of the neuropeptides/neurotransmitters investigated in the present study was demonstrated. Due to these qualities cryosubstitution provides optimal conditions for studying co-localization of neurosecretory products, using double-immunostaining procedures. In the pars distalis of the catfish pituitary several types of hypothalamus-derived nerve fibers are present between or synapting on the secretory cells. It is demonstrated that the two known catfish GnRHs are co-localized in the same nerve fiber and within these nerve fibers even co-exist in the same neurosecretory granules. GABA and vasopressin-immunolabeling each occurred in different nerve fibers. The present data demonstrate that cryosubstitution and low temperature-embedding results in an excellent morphological preservation compared to ultracryotomy and a better preserved immunoreactivity of small antigenic molecules in comparison to conventional fixation and embedding techniques.
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PMID:Application of cryosubstitution in neurohormone- and neurotransmitter-immunocytochemistry. 155 44

Endothelin (ET) receptors are present in pituitary cells and stimulate hormone release through the phosphoinositide/Ca2+ signaling system. In pituitary cell suspensions, ET caused [Ca2+]i elevations of much higher amplitudes than those induced by other vasoactive hormones, including angiotensin II, vasopressin, and noradrenalin. The action of ET was coupled to rapid and transient activation of exocytosis in gonadotrophs, thyrotrophs, somatotrophs, and lactotrophs. In contrast, angiotensin II did not stimulate luteinizing hormone release, and luteinizing hormone responses to vasopressin and noradrenalin were very small. Single gonadotrophs exhibited three types of [Ca2+]i responses to increasing doses of ET, (a) subthreshold responses, with amplitude modulation; (b) threshold-oscillatory responses, with frequency modulation; and (c) threshold-biphasic responses, as the summation of single Ca2+ spikes. The same [Ca2+]i patterns were also seen in gonadotropin-releasing hormone (GnRH)-stimulated cells. In the presence of [Ca2+]e, the amplitudes of the Ca2+ spikes progressively decreased during continuous stimulation with ET or GnRH, reaching the nonoscillatory plateau level after 200-400 sec of stimulation. In cells stimulated with GnRH, subsequent exposure to ET, GnRH, or ionomycin during the plateau phase did not elicit further increases in [Ca2+]i, whereas cells stimulated with ET responded partially to all three agents. In addition, cells exposed to ET or GnRH for 30 min, followed by a 30-min recovery period, were able to mount a full [Ca2+]i response to GnRH, but not to ET-1. Similarly, both peptides elicited rapid increases in LH release, with comparable potencies, but the response to ET decreased much more rapidly during sustained stimulation and gonadotrophs became refractory to further ET stimulation. This is in part attributable to rapid endocytosis of ET receptors during continuous agonist stimulation. These data indicate that ET exerts potent but transient secretory actions in several pituitary cell types and is a potential regulator of gonadotropin release. The initial receptor-coupling events in both ET- and GnRH-stimulated cells are similar, but the differences observed during continuous or repetitive stimulation indicate that the ET receptor pathway undergoes rapid desensitization that is critical in determining the distinct cellular responses to the two peptides.
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PMID:Calcium signaling and secretory responses in endothelin-stimulated anterior pituitary cells. 164 50

A variety of neuroendocrine cells survive and express specific neuropeptide genes for long periods of time in slice explant cultures in the presence of serum. However, before use of these slice explant cultures as experimental models for physiological and pharmacological studies on the regulation of neuropeptide gene expression, it is first necessary to evaluate their characteristics in defined (e.g. serum free) media and to control for the spontaneous electrical and synaptic activity of neurons in these cultures. In this study, brain slices from postnatal day 4 rats were cultured in serum-containing media (SCM) for 12 days to allow thinning, and then maintained in a serum-free, defined media (SFM) for 6 days. Culture slices transferred to SFM appeared healthy and numerous neuroendocrine neurons containing messenger RNA (mRNA) encoding for LHRH and magnocellular neurons containing mRNA encoding for oxytocin (OT) were detected using in situ hybridization histochemistry (ISHH). Each of these neuronal subtypes robustly produced their appropriate gene products as determined by immunocytochemical analysis. Abundant magnocellular OT neurons were found in cultures grown in either SCM or SFM. In contrast, magnocellular vasopressin (VP) neurons were rarely detected under these conditions. Inhibition of spontaneous electrical and synaptic activity in these slice explant cultures was effectively achieved by incubation for the last 2.5 days of culture in the presence of tetrodotoxin (TTX; 10(-6) M). Densitometric single cell analyses after ISHH was performed on both LHRH and OT cells. Comparisons of the density values (corresponding to mRNA levels), from these slice explants, found that: (1) cellular LHRH mRNA levels decreased in the absence of serum, whereas cellular OT mRNA levels did not significantly change under these conditions; (2) the presence of TTX in the media resulted in an overall decrease in cellular LHRH mRNA values in both SCM and SFM, and (3) the OT neurons in these slice cultures appear to be composed of a heterogeneous population, with one cell subtype responding to TTX with an increase in cellular OT mRNA levels. These data show that factors in serum and spontaneous electrical activity can differentially influence mRNA levels of LHRH cells and magnocellular OT neurons in culture.
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PMID:Maintenance of LHRH and oxytocin neurons in slice explants cultured in serum-free media: effects of tetrodotoxin on gene expression. 175 75

Effect of vasopressin, oxytocin and LHRH (10 and 20 pg/ml medium) on the proliferation and metabolism of cultured rat bone marrow stromal cells was investigated by methyl-3H-thymidine incorporation, cytochemistry and estimation of enzyme activities. Vasopressin did not change of the activity of tetrahydrofolate dehydrogenase (4HFDH), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD) and the level of reduced glutathione (GSH). However, the higher concentration of vasopressin significantly lowered the activity of acetylcholinesterase (AchE). As compared with the control cultures, stromal cells grown in the presence of oxytocin showed higher (at lower hormone concentration) and lower (at higher concentration) LDH activity as well as lower G6PD activity (only at higher concentration), while the activity of AchE and the level of GSH was not changed. LHRH significantly increased G6PD and AchE activity and decreased LDH activity in the cultured cells. As revealed by cytochemistry, LHRH specifically enhanced 4HFDH activity in reticular cells.
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PMID:Effect of vasopressin, oxytocin and LHRH on the proliferation and metabolism of rat bone marrow stromal cells in culture. 176 8


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