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Results for “VASOTOCIN”

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At least 307 records · Page 17Linked to original sources

PubMed1980

Naloxone inhibits arginine vasotocin- (AVT) induced prolactin release in urethane-anesthetized male rats in vivo.

Arginine vasotocin (AVT) (1 microgram) elicited a two-fold increase in serum prolactin (Prl) levels 10 min following its i.v. injection into urethane-anesthetized adult male rats. At 20 min after AVT administration serum Prl concentrations had essentially returned to preinjection levels. Prior treatment of the animals with 0.2 mg/kg body weight of naloxone (Nal), an opiate antagonist, completely blocked the Prl response to a single injection of AVT. Nal itself did not alter the titers of Prl at any time point. The results suggest that the in vivo Prl-releasing effect of AVT is mediated via an interaction with opiate receptors.

Animals↗

PubMed1986

Vasotocin fibers in the mesencephalon and pons of the domestic fowl. An immunohistochemical study.

Immunohistochemical analysis of the extrahypothalamic distribution of vasotocin-like immunoreactive elements within the brainstem of the domestic fowl revealed several, topographically identifiable, mesencephalic and pontine target areas. In the considered regions numerous nerve endings were surrounding perikarya or large dendritic trunks. No extrahypothalamic immunopositive perikarya have been observed in normal birds.

Animals↗

PubMed1989

Autoradiographic localization of binding sites for vasotocin in the brain and pituitary of the sea bass (Dicentrarchus labrax).

Specific binding sites for vasotocin (VT) were detected in brain and pituitary of a teleost fish, the sea bass, after in vitro incubation of tissue sections with [3H]arginine-vasopressin (AVP) and light microscopic autoradiography. Conditions for the binding assay were optimized and as a result the binding was saturable and specific. In the brain [3H]AVP binding was found to occur in the pars lateralis and the pars ventralis of the ventral telencephalon, in the pars centralis of the dorsal telencephalon, in the hypothalamic region (especially in the nucleus preopticus, in the tuberal hypothalamus and around the posterior recess), in the tectum opticum and in the noncellular layer of the corpus cerebelli. In the pituitary a high density of [3H]AVP binding was observed in the areas of the pars distalis (PD) occupied by ACTH-, TSH- and GH-cells and also in the pars intermedia (PI). The present study presents the first anatomical evidence for the presence of VT specific binding sites in teleost brain and pituitary.

Animals↗

PubMed1987

The function of dreams (REM sleep): roles for the hippocampus, melatonin, monoamines, and vasotocin.

Rapid eye movement (REM) sleep is suggested to play a role in the storage of memory, resolution of emotional experiences, and erasure of memory (forgetting). Plasticity of hippocampal physiology, morphology, and chemistry seems to be evidence for new memory formation. REM sleep, melatonin, and monoamines may be involved in the transfer of memory from the intermediate-term high-capacity buffer in the hippocampus into long-term memory storage in the neocortex. Vasotocin, which is released by melatonin, could be an amnestic agent that erases recent memory from the hippocampal-entorhinal complex during dreams.

Catecholamines↗

PubMedDate not supplied

Slow-wave sleep induced in cats by extremely small amounts of synthetic and pineal vasotocin injected into the third ventricle of the brain.

A single injection of 10(-6) pg synthetic arginine vasotocin (AVT), corresponding to about 600 molecules AVT, into the third ventricle of unanesthetized cats, induced slow-wave sleep 5 min after the injection. An equivalent amount, of a partially purified pineal AVT injected into the third ventricle, produced the same effects. After incubation with trypsin, pineal AVT completely lost its ability to induce slow-wave sleep. The slow-wave sleep induced by 10(-6) pg synthetic AVT injected intraventricularly could be matched by 1 microgram synthetic AVT injected intraperitoneally. Neither synthetic arginine vasopressin, nor synthetic oxytocin, injected intraventricularly in the amount of 10(-6) pg, was able to induce slow-wave sleep. Whereas in the control animals injected with pineal AVT after incubation with trypsin, or in the control animals injected with vasopressin or oxytocin, the paradoxical sleep averaged 21.9--22.8% of the sleep time, during a total recording time of 5 hr, in the cats injected with synthetic or pineal AVT, the paradoxical sleep was completely suppressed.

Animals↗

PubMedDate not supplied

Failure to detect radioimmunoassayable arginine vasotocin in mammalian pineals.

The presence of arginine vasopressin (AVP) and arginine vasotocin (AVT) in pineal and neural lobes of a variety of species was evaluated by radioimmunoassay using two antisera. One antiserum recognizes only AVP, while the other cross-reacts 100% with both AVP and AVT. Only traces of AVP were detected in toad and chicken pituitaries and chicken pineals, tissues found to contain abundant AVT. On the other hand, pineals from rats and rabbits, while containing measurable quantities of AVP, did not contain detectable levels (less than 6 pg) of AVT. These results fail to demonstrate the presence of AVT in rat and rabbit pineals and strongly question the role of AVT as a physiological pineal hormone in mammals.

Animals↗

PubMed1981

Narcoleptic-like alterations of the sleep cycle in cats induced by a specific vasotocin antiserum.

A specific arginine vasotocin (AVT) antiserum (10 microliter) injected undiluted into the lateral ventricle of unanesthetized cats, induced sleep onset REM periods, markedly increased the number of REM periods, and dramatically decreased REM sleep latency. The amount of total REM sleep significantly increased and the amount of total NREM sleep significantly decreased. Neither a specific arginine vasopressin or oxytocin antiserum nor a normal rabbit serum injected undiluted into the lateral ventricle in the same volume (10 microliter) was able to reproduce the effects of the AVT antiserum. It is concluded that pineal AVT is physiologically involved in the induction and/or circadian organization of REM sleep.

Animals↗

PubMed1986

Intranasal vasotocin decreases cerebrospinal fluid 5-HIAA levels in man.

A single dose (10 ng/kg) of the nonapeptide arginine vasotocin (AVT) administered intranasally to healthy young men, significantly decreased 5-HIAA levels in the lumbar cerebrospinal fluid (CSF) 8 hr after its administration. So far, this represents the smallest amount of an active substance able to alter CSF 5-HIAA levels in man. It is suggested that the decrease of CSF 5-HIAA levels after AVT administration reflects an AVT-induced reduction of the brain 5-HT turnover.

Administration, Intranasal↗

PubMed1995

Solid-phase extraction of arginine vasotocin and isotocin in fish samples and subsequent gradient reversed-phase high-performance liquid chromatographic separation.

Gradient high-performance liquid chromatography (HPLC) preceded by a solid-phase extraction (SPE) step is described for determining arginine vasotocin and isotocin, the neurohypophysial nonapeptides, in fish plasma samples. The combination of these two methods significantly improves the separation and increases the sensitivity of the assay. The proposed assay may be a useful alternative for analysis of similar nonapeptides in plasma without the use of radioisotopes, while taking into consideration a difference in detection sensitivity.

Amino Acid Sequence↗

PubMed1986

Pharmacological evidence that effects of vasotocin on brain maturation are mediated by GABA mechanisms.

Active sleep, brain weight as well as total lipids and galactolipids were assayed in 8-day-old rat pups, after daily administration (between 2 and 8 days of postnatal age) of saline, arginine vasotocin (AVT) (10(-7) mg), picrotoxin (5 x 10(-5) mg), valproic acid (10(-5) and 10(-6) mg) or of AVT + picrotoxin and AVT + valproic acid. AVT increases active sleep and decreases the weight, total lipids and the galactolipids of the brain. Although picrotoxin alone was without any apparent effects on maturational parameters, when administered together with AVT, it completely prevented AVT from producing its effects. Valproic acid had AVT-like effects when administered in a higher dose (10(-5) mg), but was without any apparent effects when administered in the lower dose (10(-6) mg). However, both doses intensely potentiated the effects of AVT. Since both drugs specifically interfere with the GABAergic neurotransmission, it is concluded that AVT retards the accumulation of brain lipids by activating a GABAergic pathway.

Animals↗

PubMed1988

Distribution of immunoreactive vasotocin and mesotocin in the chicken gastrointestinal tract.

Immunoreactive arginine vasotocin (AVT) and mesotocin (MT) were measured in heart, breast muscle, adrenals, testes, and different parts of the gastrointestinal tract in adult male chickens. Neither of the peptides were detected in liver, testis, heart and breast muscle. The amounts of AVT and MT in the adrenals were 167 +/- 25 and 669 +/- 198 pg/gland, respectively. Considerable amounts of immunoreactive peptides were found in the gastrointestinal tract with the highest concentration in the proventriculus (4.18 +/- 0.31 ng AVT and 16.58 +/- 0.86 ng MT per organ). Dose-response curves of duodenal and proventriculus extracts were parallel with synthetic AVT and MT standards.

Animals↗

PubMed1985

Response of amphibian (Ambystoma tigrinum) oviduct to arginine vasotocin and acetylcholine in vitro: influence of steroid hormone pretreatment in vivo.

Oviducts of the salamander Ambystoma tigrinum contract in vitro in response to stimulation by arginine vasotocin (AVT) and acetylcholine (ACh). Steroid hormone pretreatment significantly affects the responsiveness of the oviductal tissue to AVT and ACh. Oviducts initially pretreated with estradiol, testosterone and saline or a combination of estradiol and testosterone exhibit no response to AVT and only saline or estradiol/testosterone treated oviducts respond to ACh. Secondary pretreatment with progesterone stimulated a significant increase in responsiveness to AVT and ACH in all groups.

Acetylcholine↗

PubMedDate not supplied

Distribution of vasotocin- and mesotocin-like immunoreactivities in the brain of the South African clawed frog Xenopus-laevis.

In order to obtain more insight into primitive and derived conditions of neuropeptidergic systems in vertebrates, in particular amphibians, we have studied immunohistochemically the distribution of vasotocin (AVT) and mesotocin (MST) neuronal elements in the brain of the South African clawed frog Xenopus laevis. Apart from a well-developed hypothalamohypophysial system, the antibodies revealed the existence of extrahypothalamic AVT- and MST-immunoreactive cell groups as well as extensive extrahypothalamic networks of immunoreactive fibres, thus confirming the phylogenetic constancy of this condition in vertebrates. The wide distribution of AVT- and MST-immunoreactive fibres throughout the brains of amphibians suggests that the two neuropeptidergic systems are involved not only in hypothalamohypophysial interactions, but also, as in mammals, in a variety of other brain functions. In particular, the relationship of AVT- and MST-immunoreactive fibres with catecholaminergic cell bodies was noted. The present study has underscored once again that considerable differences in relative densities of AVT- and MST-immunoreactive fibres occur between species, even within a single order of vertebrates.

Animals↗

PubMed1992

Interactions between vasotocin and other corticotropic factors on the frog adrenal gland.

The adrenocortical cells of the amphibian interrenal (adrenal) gland are controlled by multiple factors including neuropeptides and classical neurotransmitters. In particular, it has recently been shown that vasotocin (AVT), the amphibian counterpart of vasopressin, is a potent stimulator of frog corticosteroidogenesis. In the present study, we have investigated the possible interactions between AVT and other regulatory factors on frog interrenal tissue. When AVT (10(-9) M) and serotonin (10(-6) M) were infused together, a strict addition of the individual effects was observed. Similar results were obtained with concomitant infusion of AVT and vasoactive intestinal peptide or AVT and ACTH. In contrast, when AVT (10(-9) M) and acetylcholine (5 x 10(-5) M) were added together, the increase in corticosteroid secretion was less than additive. Dopamine induced a significant reduction of AVT-evoked stimulation of corticosterone production. These results indicate that regulatory peptides or classical neurotransmitters which participate in the control of adrenal steroidogenesis may interact on their target cell to modulate the activity of their congeners.

Acetylcholine↗

PubMed2004

Region-specific testosterone modulation of the vasotocin-immunoreactive system in male dark-eyed junco, Junco hyemalis.

The nonapeptide vasotocin (VT) is the avian equivalent of the mammalian antidiuretic hormone vasopressin and is believed to control aggressive and reproductive behaviors. Brain VT distribution has been described in several domesticated avian species. We previously demonstrated that VT distribution in the brain of a free-ranging male passerine, the dark-eyed Junco, Junco hyemalis, resembles that in domesticated birds. A preliminary study also suggested that the VT-immunoreactive (VT-ir) system of juncos is regulated by testosterone (T), as is the case of galliforms. To test this hypothesis, we investigated the effects of castration and T replacement on brain VT-ir innervation in adult male juncos. Castration reduced VT-ir innervation in the lateral septum (SL), the medial preoptic nucleus, the nucleus of the stria terminalis and the intercollicularis nucleus. These effects of castration were largely reversed by T treatment at high physiological doses, but significantly so only for the SL. Given the demonstrated behavioral role of the above VT-ir-containing brain regions, the results suggest that these regions may be sites of action of VT on reproductive behaviors.

Animals↗

PubMed2004

Co-localization of neuronal nitric oxide synthase with arginine-vasotocin in the preoptic-hypothalamo-hypophyseal system of the teleost Oreochromis niloticus.

This study provides evidence that, in the preoptic-hypothalamo-hypophysial system of the teleost Oreochromis niloticus, several sub-populations of arginine-vasotocin (AVT)-producing neurons and neurosecretory fibers terminals express neuronal nitric oxide synthase (nNOS)-like molecules. The co-localization between nNOS and AVT was demonstrated by means of double immunofluorescence staining with the confocal microscope. This study is the first to provide evidence that nNOS may be co-localized with AVT in neurons of a non-mammalian vertebrate.

Animals↗

PubMed2006

Arginine vasotocin, isotocin and melatonin responses following acclimation of gilthead sea bream (Sparus aurata) to different environmental salinities.

Gilthead sea bream (Sparus aurata) is a euryhaline species with a capacity to cope with demands in a wide range of salinities and thus is a perfect model-fish to study osmoregulatory responses to salinity-adaptive processes and their hormonal control. Immature sea bream acclimated to different salinities, i.e. SW (38 per thousand), LSW (5 per thousand) and HSW (55 per thousand), were kept at 18 degrees C under natural photoperiod. Arginine vasotocin (AVT) and isotocin (IT) in plasma and pituitary were determined by HPLC. Plasma melatonin (Mel) was assayed by RIA. Plasma osmolality, ion concentrations (Na(+), K(+), Ca(2+), Cl(-)) and Na(+),K(+)-ATPase activity in gill were measured. A steady increase in plasma AVT, along with increasing water salinity was observed. Pituitary IT concentration in HSW-acclimated fish was significantly higher than that in LSW group. AVT/IT secretory system of sea bream does appear to be involved in the mechanism of long-term acclimation to different salinities. The distinct roles and control mechanisms of both nonapeptides are suggested. Plasma Mel was significantly higher in LSW compared with both HSW and SW groups. Data indicate that the changes in Mel level are linked to osmoregulation. Further studies are required to elucidate a complex role of AVT, IT and Mel in sea bream osmoregulation.

Acclimatization↗

PubMed2004

Dietary intake effects on arginine vasotocin and aldosterone in cloacal fluid of whitebellied sunbirds (Nectarinia talatala).

The main objective of this study was to determine whether or not the renal outputs of the osmoregulatory hormones arginine vasotocin (AVT) and aldosterone (ALDO) reflect the osmotic status of whitebellied sunbirds (Nectarinia talatala). The birds were fed a range of sucrose concentrations (from 0.07 to 2.5 mol/l, with osmolalities of 70 to approximately 5,800 mosM/kg), and adjusted their intakes so that they drank large volumes of dilute diets and small volumes of concentrated diets. Renal fluid outputs were appropriately regulated so that large volumes of cloacal fluid (CF) were voided on the dilute diets and small volumes on the concentrated diets. Accordingly, plasma AVT concentrations increased with increasing sugar concentration; however, AVT outputs in CF did not change in a similar manner, rather they decreased as dietary concentration increased. It was not possible to measure plasma ALDO concentrations in the small sunbirds because of insufficient blood samples available; however, ALDO outputs in CF did vary with the sucrose diets and renal function, being highest on the most concentrated diet. In addition ALDO output in CF fell markedly when sodium was added to the 0.5 mol/l sucrose diet. We conclude that in sunbirds fed increasingly concentrated sucrose solutions, changes in CF outputs of ALDO, but not AVT, appear to reflect the water flux and hydration state of these birds.

Aldosterone↗