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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binding sites for oxytocin (OXT) and alpha-melanocyte-stimulating hormone (alpha-MSH) in brain of homozygous Brattleboro rats were immunocytochemically visualized after ventricular administration of the peptides by Accurel implants. Two patterns were found: 'ring type' staining in perineuronal structures was observed in CA1 and CA3 areas of ventral hippocampus and in subiculum for OXT implanted brains and a very weak staining in striatum for alpha-MSH-implanted brains; cytoplasmic staining of intracellular binding sites was observed in the bed nucleus of the stria terminalis (BST) in brains with OXT implants and in the anterodorsal thalamic nucleus (AD) and postcingulate cortex in brains with alpha-MSH implants. These localizations are different from those described for vasopressin binding sites in the same rat strain.
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PMID:Immunocytochemically stained binding sites for oxytocin and alpha-melanocyte-stimulating hormone in rat brain following ventricular administration. 242 69

In transverse hippocampal slices from rat and guinea pig brains, we obtained unitary extracellular recordings from nonpyramidal neurones located in or near the stratum pyramidale in the CA1 field and in the transition region between the CA1 and the subiculum. In rats, these neurones responded to oxytocin at 50-1000 nM by a reversible increase in firing rate. The oxytocin-induced excitation was suppressed by a synthetic structural analogue that acts as a potent, selective antioxytocic on peripheral receptors. Nonpyramidal neurones were also excited by carbachol at 0.5-10 microM. The effect of this compound was postsynaptic and was blocked by the muscarinic antagonist atropine. In guinea pigs, by contrast, nonpyramidal neurones were unaffected by oxytocin, although they were excited by carbachol. Light microscopic autoradiography, carried out using a radioiodinated selective antioxytocic as a ligand, revealed labeling in the subiculum and in the CA1 area of the hippocampus of rats, whereas no oxytocin-binding sites were detected in the hippocampus of guinea pigs. Our results indicate (i) that a hippocampal action of oxytocin is species-dependent and (ii) that a positive correlation exists between neuronal responsiveness to oxytocin and the presence in the hippocampus of high-affinity binding sites for this peptide.
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PMID:Correlation between oxytocin neuronal sensitivity and oxytocin receptor binding: an electrophysiological and autoradiographical study comparing rat and guinea pig hippocampus. 253 77

The ontogeny of oxytocin receptors in rat forebrain was studied using the selective oxytocin receptor antagonist 125I-d(CH2)5[Tyr(Me)2, Thr4, Tyr-NH29]OVT [( 125I]-OTA). With in vitro receptor autoradiography, binding wa noted on the first postnatal day in dorsal subiculum and thalamus. On postnatal days 5-18, intense labeling was evident in posterior cingulate cortex, dorsal subiculum, lateral septum, and the CA1 subfield of hippocampus. Of these regions only the lateral septum expressed oxytocin receptors in adult brain. Competition studies on coronal sections through posterior cingulate, septum, and dorsal subiculum at P10 demonstrated that transient binding sites in these areas were indeed oxytocin selective (OXY greater than AVP greater tha V1 greater than V2). Result of saturation studies on cingulate membranes from 10-day-old pups agreed favorably with previous reports of the kinetics of [125I]-OTA binding to adult oxytocin receptors (Kd = 0.1 nM in P10 cingulate cortex vs. 0.07 nM for adult ventral subiculum). In contrast to these evanescent developmental sites, oxytocin receptors in the bed nucleus of the stria terminalis and the ventromedial nucleus of the hypothalamus only appeared in adulthood, presumably in response to the surge of gonadal steroids at puberty.
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PMID:Ontogeny of oxytocin receptors in rat forebrain: a quantitative study. 255 21

Extracellular recordings from cells in the CA1b region of the in vitro hippocampal slice preparation demonstrate that bath-applied AVP (10(-6)-10(-12) M) frequently results in a decrease in the orthodromically evoked population spike amplitude. This suggests that AVP inhibits CA1 pyramidal cell firing in response to an orthodromic volley. This effect appears to be receptor-mediated, since a potent antagonist of the AVP V1 (vasopressor) receptor and a mixed oxytocin/vasopressin antagonist prevented the decrease in population spike amplitude observed in response to bath application of AVP. Hippocampal slices prepared from rats injected two days earlier with 1.0 micrograms AVP (intracerebroventricular) display increased sensitivity to the depressant effects of AVP at lower doses compared to controls. These results suggest that pretreatment of rats with AVP may alter the sensitivity of hippocampal cells to the depressant effects of this neuropeptide.
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PMID:Altered sensitivity to arginine vasopressin (AVP) in area CA1 of the hippocampal slice following pretreatment of rats with AVP. 367 73

Microinjection of oxytocin into the paraventricular nucleus of the hypothalamus or into the CA1 field of the hippocampus induced a dose-dependent increase in the number of penile erection and yawning episodes in male rats. The minimal effective dose of oxytocin injected into the paraventricular nucleus was 3 ng. This dose induced the above-mentioned behaviors in 60% of the treated rats. Doses of 9 ng or higher induced the symptomatology in more than 85% of the animals. On the other hand, when the peptide was injected into the CA1 field of the hippocampus, 9 ng bilaterally were necessary to elicit penile erection and yawning in 62% of the rats. Arg8-vasopressin, which only differs from oxytocin in two amino acids, induced penile erection and yawning when injected either into the paraventricular nucleus or into the hippocampus, but was 5-10 times less potent than oxytocin. Oxytocin injection into the lateral septum, caudate nucleus, subiculum, preoptic area, ventromedial nucleus and supraoptic nucleus, was ineffective. The powerful effect of oxytocin on the induction of yawning and penile erection, suggests a physiological role of hypothalamic and hippocampal oxytocin in the regulation of such responses.
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PMID:Oxytocin-induced penile erection and yawning: site of action in the brain. 380 3

Oxytocin and vasopressin increased the rate of firing of a class of presumed non-pyramidal neurones located in the CA1 area of rat hippocampal slices. This excitatory effect persisted in conditions of synaptic uncoupling. In contrast, pyramidal neurones were either unaffected by neurohypophysial peptides or showed one or several of the following effects: a decrease in firing rate in cells which were spontaneously active; a slight membrane hyperpolarization; and an increase in the rate of occurrence of spontaneous inhibitory postsynaptic potentials. We therefore propose that oxytocin and vasopressin excite directly a class of non-pyramidal inhibitory interneurones, whereas their observed effect on pyramidal neurones is indirect and inhibitory.
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PMID:Contrasting effects of neurohypophysial peptides on pyramidal and non-pyramidal neurones in the rat hippocampus. 647 5

Neurohypophysial peptides were applied by superfusion to rat hippocampal slices. The peptides, arginine vasopressin, lysine vasopressin, arginine vasotocin and oxytocin, increased the activity of 88% of spontaneously active cells in the CA1 region and induced firing in many neurones that were not spontaneously active. The peptide sensitive cells appeared to be pyramidal cells rather than interneurones. The four peptides were found to be of roughly equivalent potency, producing a reversible, dose-dependent response in the range 10(-9) to 10(-6)M. Most of the cells were tested with more than one peptide and were always found to respond either to all or to none of them. The analogue [7-glycine]oxytocin and the deamino, dicarba derivatives of oxytocin and vasopressin were about as active as the parent compounds, but the oxytocin fragment prolyl-leucyl-glycinamide had no effect, and desglycinamide vasopressin was extremely weak. Responses to the peptides could be blocked by "specific" antagonists. The results suggest that all of the peptides are acting upon a single class of receptor.
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PMID:Neurohypophysial peptides and the hippocampus. II. Excitation of rat hippocampal neurones by oxytocin and vasopressin applied in vitro. 666 25

The effect of NG-nitro-L-arginine methyl ester (NAME), a potent inhibitor of nitric oxide (NO) synthase, injected into different brain areas on penile erection and yawning induced by apomorphine or oxytocin was studied in male rats. The compound was found to be able to prevent the above behavioral responses dose dependently when injected into the paraventricular nucleus of the hypothalamus (PVN), but not in the caudate nucleus, medial septum, preoptic area, and the CA1 field of the hippocampus. When injected in the PVN, 5 micrograms of NAME induced a 30% reduction of apomorphine and oxytocin responses, while 20 micrograms induced an almost complete reduction. The effect of NAME seems to be related to the inhibition of guanylate cyclase secondary to the prevention of NO formation, because a dose-dependent reduction of apomorphine and oxytocin responses was obtained also with the inhibitor of guanylate cyclase methylene blue injected intracerebroventricularly (100-400 micrograms ICV), but not into the PVN. The results provide further support for a neurotransmitter role of central NO in the control of penile erection and yawning.
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PMID:Prevention by NG-nitro-L-arginine methyl ester of apomorphine- and oxytocin-induced penile erection and yawning: site of action in the brain. 793 38

Since previous studies in vivo have shown that oxytocin is metabolized by rat synaptic membrane-bound aminopeptidase- and endopeptidase-like enzymes, the proteolytic conversion of oxytocin was studied in vivo after microinjection in the rat hippocampus, a brain area that contains oxytocinergic nerve endings and receptors. Isolation of the formed peptide fragments from the injected brain area after homogenization and adsorption on a Sep-Pak cartridge by high performance liquid chromatography, and their characterization by amino acid analysis, revealed that, when oxytocin (50 nmol in 0.5 microliter) was microinjected in the CA1 field of the rat hippocampus, only the N-terminal fragment oxytocin(1-8) was formed in such amount that could be characterized. The microinjection of [3H-Tyr2]oxytocin (10 pmol) revealed that in addition to oxytocin(1-8), free [3H]tyrosine was formed. Taken together with previous findings showing that C-terminal oxytocin fragments as well oxytocin(1-8) are formed by membrane-bound aminopeptidases and endopeptidases in vitro, respectively, the results suggest that, in addition to aminopeptidases, endopeptidase-like enzymes are involved in the proteolysis of endogenous brain oxytocin.
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PMID:Proteolytic conversion of oxytocin in vivo after microinjection in the rat hippocampus. 833 47

Localization of oxytocin- and vasopressin-binding sites has so far been studied in the rat brain by means of film autoradiographs. The disposal of iodinated ligands with high specificity has allowed us to develop histoautoradiography on emulsion-coated sections and to reinvestigate on a microscopic scale the distribution of these sites in the telencephalon (septum, striatopallidal system, amygdala and hippocampus). This technique showed that oxytocin and vasopressin labelling presented distinct distributions and coincided with delimited zones, corresponding to anatomical subdivisions defined on cytoarchitectural and immunocytochemical bases. Vasopressin sites were seen in the dorsal and intermediate parts of the lateral septum and the juxtacapsular nucleus of the bed nucleus of the stria terminalis. Oxytocin sites were located in the ventral and intermediate parts of the lateral septum, the oval and the principal nuclei of the bed nucleus of the stria terminalis and the septofimbrial nucleus. In the striatopallidal system, vasopressin sites were found in the accumbens nucleus and the fundus striati, whereas oxytocin sites were in the accumbens nucleus, the head, and the posterolateral parts of the caudate-putamen, the striatal cell bridges, and the olfactory tubercle. In the amygdala, vasopressin sites were not found, but oxytocin sites were located in the central, medial, and basomedial nuclei. In the hippocampus, vasopressin sites were located in the dentate gyrus (polymorph and molecular layers), and oxytocin sites, in the subiculum (molecular and pyramidal layers) and in the field CA1 of Ammon's horn (lacunosum moleculare and pyramidal layers). The localization of the binding sites at the microscopic level permitted us to reinvestigate whether or not correlation existed in a same area between innervation, electrophysiological effects, and presence of binding sites.
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PMID:Histoautoradiographic detection of oxytocin- and vasopressin-binding sites in the telencephalon of the rat. 839 91


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