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

Against the background of renewed interest in the existence of reflex ovulation in many animal species and the possibility of its existence in man, this review on current research efforts embraces the multitude of nervous influences and stimuli accompanying cohabitation. Species showing reflex ovulation are not restricted to those using this as the sole ovulatory mechanism, but include also so-called facultative ovulators, which seem to use this mechanism as a last resort to assure reproductive capacity under adverse situations (rat); and species which for the length of the standing heat period become temporarily induced ovulators for the optimal coordination of all necessary steps to assure fertility (cattle, pig, sheep); and species in which frequent cohabitation (rat) or a single coitus after artificial insemination (sheep) assures either optimal ovulation or conception rates. Copulation might not always be essential; some of the cohabitation-related reflexes might be transmitted by olfactory, ocular, tactile and acoustic stimuli; emotions may play a role. These stimuli are transmitted to the CNS from the periphery by afferent nervous pathways, and are translated in the thalamic-hypothalamic-pituitary complex into neurohormonal phenomena, causing ovulation; or may cause, mainly by LH and/or oxytocin discharge, an acceleration or augmentation of processes involved in spontaneous ovulation. Intensive biochemical and pharmacological studies have unveiled some of the neurohormonal mechanisms involved in the hypothalamus and how these stimuli are transmitted to the pituitary or received at the ovarian level, as hormonal or neurohormonal phenomena.
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PMID:Current research in coitus-induced ovulation: a review. 81 May 83

Using autoradiography on film, specific binding sites for arginine-vasopressin (AVP) and for oxytocin (OT) were localized in various areas of the brain of adult male guinea pigs. Vasopressin binding sites were detected with [3H]AVP or with [125I]VPA, a recently synthetized linear vasopressin antagonist radiolabeled with 125I. [125I]VPA and [3H]AVP yielded similar results, thus suggesting that AVP binding sites present in the guinea pig brain are V1 type receptors. Supporting evidence on this was obtained in competing studies using structural analogues allowing to discriminate V1 receptors from V2 and from OT receptors. Oxytocin binding sites were labeled with [3H]OT or with the iodinated OT antagonist [125I]OTA; both ligands yielded similar results. The localization in the guinea pig brain of AVP binding sites differed from that of OT binding sites. AVP binding sites were mainly detected in the olfactory bulb and throughout the cerebral cortex. Oxytocin binding sites were most noticeable in the hypothalamic ventromedial nucleus, in the amygdaloid complex and in restricted areas of the cerebral cortex. A comparison of the present data with those previously described in the rat, the mouse, the human and the hamster brain suggests that similar binding sites are present in these species, but that their anatomical distribution differs markedly. These data are discussed in relation to immunocytochemical and electrophysiological data which suggest that binding sites detected by autoradiography may represent, at least in part, functional neuronal receptors.
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PMID:Localization and characterization of binding sites for vasopressin and oxytocin in the brain of the guinea pig. 133 Feb 6

Oxytocin facilitates maternal behaviour in sheep. In the present study, we searched for the presence of oxytocin and vasopressin binding sites in the sheep olfactory bulb, a brain area which is thought to be involved in specific bond formation between the ewe and its lamb. Using in vitro autoradiography, we observed binding of tritiated vasopressin to the glomerular layer of the olfactory bulb. Competition studies performed with structural analogues and the use of a 125I-labelled linear vasopressin antagonist suggested that sites which bind vasopressin are V1 type receptors. In contrast, specific binding sites for oxytocin in the olfactory bulb could be detected neither in control females, nor in ovariectomized females treated with estradiol nor in postparturient ewes, although such sites were present in the uterus.
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PMID:Autoradiographic detection of vasopressin binding sites, but not of oxytocin binding sites, in the sheep olfactory bulb. 133 68

Our earlier electrophysiological work provided evidence of a direct input to the supraoptic nucleus (SON) from the olfactory bulbs; however, these experiments could not determine if the input originated in the main and/or accessory portions of the olfactory bulb. Here, a connection between the accessory olfactory bulb (AOB) and the SON of the rat was examined using a combination of anatomic techniques. We employed neurophysin immunocytochemistry to delineate the morphological boundaries of the SON and the proximal arborizations of supraoptic dendrites. Accessory olfactory bulb efferents to the SON were studied by injection of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the AOB. The distribution of retrogradely labeled cells within the AOB was also determined after injection of either rhodamine-labeled latex microspheres (rhodamine beads) or Fluoro-Gold (FG) into the SON. Neurophysin immunocytochemistry revealed that SON dendrites extended beyond the generally accepted boundaries of the nucleus, coursing ventrolaterally along the surface of the periamygdaloid cortex. Anterograde tract tracing with WGA-HRP labeled AOB efferents including a dense plexus of terminals and fibers around the ipsilateral SON along the path of the ventrally projecting dendrites. Injections of retrograde tracers into the SON resulted in rhodamine bead or FG labeling of mitral cells throughout the ipsilateral AOB. Taken together, these anatomic studies suggest a direct projection from the accessory olfactory bulb to the SON of the rat and thus a vomeronasal organ to SON pathway.
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PMID:Supraoptic nucleus afferents from the accessory olfactory bulb: evidence from anterograde and retrograde tract tracing in the rat. 138 86

The effects of circulating oxytocin on permeability of the blood-brain barrier (BBB) to L-[3H]leucine were studied in anaesthetized rats using the intracarotid, single pass, bolus injection technique. After bolus intracarotid oxytocin injection (10(-9) M), there were no differences in [3H]leucine uptake, compared with controls, in any of eight brain regions with a 'tight' BBB (olfactory bulb, frontal cortex, visual cortex, corpus striatum, hippocampus, thalamus, hypothalamus and colliculi) or in BBB-free, 'leaky' structures (pineal gland, choroid plexus, neuro-intermediate pituitary, anterior pituitary). [3H]leucine uptake by the 'leaky' structures was 2.4x and 2.6x uptake by 'tight' regions in the oxytocin and control groups respectively. In morphine-dependent rats, naloxone increased oxytocin secretion 28-fold within 5 min, but did not affect [3H]leucine uptake for any BBB-protected brain region or BBB-free 'leaky' structure. Accumulation of [3H]leucine was 8.3x and 7.0x greater in the 'leaky' structures than in the 'tight' regions in the naloxone and control groups respectively; [14C]inulin accumulation by each 'tight' region (measured simultaneously with [3H]leucine to determine the vascular space) was not affected by naloxone. It is concluded that even very high blood plasma concentrations of oxytocin do not affect BBB permeability for leucine. It is unlikely that altered BBB permeability, at least for amino acids, contributes to CNS changes during naloxone-provoked morphine withdrawal.
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PMID:Transfer of [3H]leucine across the blood-brain barrier at high blood-side oxytocin concentrations in normal and morphine-dependent rats. 140 9

Most studies investigating the behavioral effects of centrally administered oxytocin (OT) have been confined to single acute injections followed by brief behavioral observations lasting up to 90 min. The present study examines the behavioral effects of chronic, centrally administered OT in male rats observed continuously for prolonged periods of time. Either artificial cerebrospinal fluid or OT was centrally infused (via osmotic minipump) to gonadally intact male rats. Behavioral observations were made on males paired with either ovariectomized or estrous females during a 6-h time period. Most striking was the observation that durations of physical contact were doubled in pairs containing OT-infused males, even in the absence of sexual interactions. Also, OT-infused males showed significantly higher levels of anogenital sniffing of females and autogrooming; however, sexual interactions were unaffected by chronic OT. Chronic OT had no effect on body temperature, analgesia, or exploratory behavior in an open field. These findings suggest that chronic OT in male rats has behavioral effects that may significantly enhance adult social (nonsexual) interactions, possibly through alterations in olfactory and somatosensory information processing.
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PMID:Enhanced social interactions in rats following chronic, centrally infused oxytocin. 144 80

Syrian hamsters can communicate using a distinctive form of scent marking called flank marking. Vasopressin-sensitive neurons within the medial preoptic-anterior hypothalamic continuum (MPOA-AH) play a critical role in the control of this form of olfactory communication. Extrahypothalamic regions may also mediate hamster flank marking. Since the MPOA-AH and the periaqueductal gray (PAG) are reciprocally connected, the present study investigated whether PAG neurons are involved in the control of flank marking. The first study found that microinjection of vasopressin, but not oxytocin or saline, into the PAG induced high levels of flank marking in male (n = 8) and female (n = 5) hamsters (P less than 0.01). The second study demonstrated that microinjection of vasopressin into the PAG stimulated flank marking in a dose-dependent manner in both male (n = 7) and female (n = 11) hamsters (P less than 0.01). These data suggest that vasopressin-responsive neurons within the periaqueductal gray participate in the control of hamster flank marking.
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PMID:Microinjection of arginine-vasopressin into the periaqueductal gray stimulates flank marking in Syrian hamsters (Mesocricetus auratus). 161 73

Several recent studies have suggested that the neurohypophyseal peptide oxytocin may have a role within the brain to mediate various forms of affiliative behavior. As the regulation of oxytocin function may be largely determined by the number and distribution of its membrane bound receptor, we investigated oxytocin receptor distribution in two Peromyscus species selected for differences in affiliative behavior. Using in vitro receptor autoradiography with the selective oxytocin receptor ligand [125I]d(CH2)5[Tyr(Me)2,Tyr-NH9(2)]OVT ([125I]OTA), we compared Peromyscus maniculatus, a polygamous species, to Peromyscus californicus, a monogamous species. Marked species differences in the distribution of [125I]OTA were apparent in several brain areas, including olfactory pathways, bed nucleus of the stria terminalis, amygdala, dorsal lateral septum, and several cortical regions. In addition, gender differences in the binding pattern were evident in several regions, mostly due to sexually dimorphic patterns in the polygamous species, P. maniculatus. To further compare these species, the binding of a [3H]arginine-vasopressin antagonist was assessed in alternate sections from those used for [125I]OTA. Relative to oxytocin receptors, binding to arginine-vasopressin receptors showed fewer species differences, although the monogamous species appeared to have more arginine-vasopressin receptors in the neocortex and lateral septum. The striking differences in oxytocin receptor distribution are consistent with earlier studies in other rodents, suggesting that oxytocin may have an important role for mediating species-typical patterns of social affiliation.
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PMID:The comparative distribution of forebrain receptors for neurohypophyseal peptides in monogamous and polygamous mice. 165 22

The effects of oxytocin (OXT), arginine- and lysine-vasopressin (AVP and LVP) and an OXT-receptor antagonist on cocaine-induced sniffing behaviour were investigated in rats. OXT, but not AVP or LVP injected subcutaneously (s.c.) attenuated cocaine-induced sniffing. The effect of OXT (s.c.) was inhibited by an OXT-receptor antagonist administered intracerebroventricularly (i.c.v.). I.c.v. administration of different doses of OXT in nanogram quantities caused a dose-dependent attenuation of cocaine-induced sniffing. Local cerebral microinjection of OXT into the accumbens nucleus and olfactory tubercle but not into the olfactory nucleus, central amygdaloid nucleus or caudate nucleus, inhibited the cocaine-induced sniffing behaviour. These results demonstrate that OXT selectively attenuates the cocaine-induced stereotyped behaviour through basal forebrain target sites.
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PMID:Selective attenuation of cocaine-induced stereotyped behaviour by oxytocin: putative role of basal forebrain target sites. 189 Oct 73

Mitral cells of the main and accessory olfactory bulbs have been shown to project monosynaptically to the supraoptic nucleus (SON) via the lateral olfactory tract (LOT) which uses excitatory amino acid transmitters. Data collected during characterization of these projections suggested that synaptic activation of SON neurons via LOT stimulation in slices influenced the incidence of dye-coupling. The present study pursued this suggestion using horizontally cut slices from male, virgin female and lactating rats. Neurons were confirmed to be excited by electrical stimulation of the tract, injected with Lucifer yellow, and synaptically activated for 10 min at 10 Hz (n = 92). Another 94 neurons were similarly confirmed and injected, but received no further stimulation. In an additional 8 slices, injected neurons were antidromically activated for 10 min at 10 Hz. Analyses done on 194 injected neurons from the 3 groups showed that synaptic activation resulted in a significant (P less than 0.01) increase in the incidence of coupling only in tissue from lactating rats. This increase was entirely due to larger numbers of cells being coupled dendrodendritically to the injected cells in the stimulated slices. Antidromic activation did not influence coupling. Increased coupling occurred among both oxytocin and vasopressin cell types. This is the first report of increased coupling resulting from synaptic activation in mammalian CNS. Changes seen only in lactating rats may be related to their altered SON ultrastructural morphology (i.e. dendritic bundling). Strong olfactory and vomeronasal input associated with some maternal behaviors may increase neuronal coupling and enhance hormone release in response to other incoming stimuli (e.g. suckling, dehydration).
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PMID:Activation of excitatory amino acid inputs to supraoptic neurons. I. Induced increases in dye-coupling in lactating, but not virgin or male rats. 216 99


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