SEARCH · PubMed Health

Results for “VASOTOCIN”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed1983

Proteolytic conversion of arginine-vasotocin by synaptic membranes from rat and chicken brain.

This paper reports studies on the biotransformation of the nonapeptide arginine-vasotocin (AVT) by both rat and chicken brain synaptic membranes. The fragments which were formed during digestion of AVT1-9, were isolated by high pressure liquid chromatography (HPLC) and chemically characterized by amino acid composition, NH2-terminal amino acid residues and the presence of 14C-radioactivity of the residue glycinamide-9. The major peptide fragments of AVT were: (formula; see text) Time course experiments showed the precursor-product interrelationships between these peptides. The results demonstrate that the conversion of AVT by synaptic membranes involves primarily the action of aminopeptidase activity. Comparison between membrane fractions from rat and chicken brain showed that AVT is converted by a similar proteolytic mechanism in chicken brain, but that differences in activity of the aminopeptidase exist. The results are discussed in view of the concept that AVT serves as precursor for neuropeptides with differential activities in non-mammalian vertebrates.

Aminopeptidases↗

PubMed1988

Testosterone-sensitive vasotocin-immunoreactive cells and fibers in the canary brain.

A sexual difference in vasotocin (VT) immunoreactivity was observed in the canary brain. The male canary displays denser VT innervation of the lateral septum and more VT-immunoreactive cells are visible in the dorsal diencephalon than in the female canary. This sex difference is the consequence of gonadal influences. Castration of male canaries resulted in a substantial decrease of VT immunoreactivity in these septal and diencephalic cells and fibers. Testosterone administration to castrated males restored the original intensity of fiber and cell staining. Testosterone treatment of female canaries induced strong VT immunostaining in the above regions similar to that in the male canary.

Animals↗

PubMed1992

Sexually dimorphic concentrations of arginine vasotocin in sensory regions of the amphibian brain.

Arginine vasotocin (AVT) regulates reproductive behaviors in amphibians. We measured AVT in the brains of bullfrogs (Rana catesbeiana) and newts (Taricha granulosa) using radioimmunoassay. In bullfrogs, AVT concentrations were greater in males, compared to females, in the amygdala pars lateralis, optic tectum, and tegmentum. Concentrations in the dorsolateral nucleus were greater in females. In newts, AVT concentrations were also greater in the tectum and tegmentum of males. AVT may modulate dimorphic behaviors by acting at these sites.

Animals↗

PubMed1982

Effects of arginine vasotocin on REM sleep in narcoleptics and in symptomatic hypersomniacs.

Arginine vasotocin (AVT), in doses of 1.5 microgram, administered intranasally to two narcoleptics (a male aged 42 years and a female aged 35 years), as well as to 5 symptomatic hypersomniacs (3 females and 2 males), aged 25-57 years, induced very rapidly in most instances in sleep with REM periods at onset and markedly increased in amount of REM sleep during a fixed period of 180 min of sleep recording. After AVT administration there was a significant shortening of the time of occurrence of the first REM sleep period both in narcoleptics (t test = 0.05 greater than P greater than 0.025) and in symptomatic hypersomniacs (t test = 0.02 greater than P greater than 0.01).

Adult↗

PubMed1987

d(CH2)5Tyr(Me)-[Orn8]vasotocin, a potent oxytocin antagonist, antagonizes penile erection and yawning induced by oxytocin and apomorphine, but not by ACTH-(1-24).

Intraventricular (i.c.v.) injection of d(CH2)5-Tyr(Me)-[Orn8]vasotocin, a potent oxytocin antagonist, antagonized in a dose-dependent manner (10-100 ng) penile erection and yawning induced by the systemic injection of apomorphine (80 micrograms/kg s.c.) or by the i.c.v. injection of oxytocin (30 ng). In contrast, the oxytocin antagonist, even at the dose of 10 micrograms, did not modify penile erection and yawning induced by the i.c.v. injection of ACTH-(1-24). These results suggest that apomorphine, but not ACTH-(1-24), induce penile erection and yawning by releasing oxytocin in some brain area.

Adrenocorticotropic Hormone↗

PubMed1990

Molecular cloning of two distinct vasotocin precursor cDNAs from chum salmon (Oncorhynchus keta) suggests an ancient gene duplication.

The structures of two different vasotocin precursors from chum salmon brain have been elucidated through the molecular cloning of their corresponding cDNAs. Although the predicted precursors, consisting respectively of 153 and 158 amino acids, have the same structural organisation, they show 35% amino acid sequence divergence, of which only approximately half are isofunctional substitutions. Remarkably, while the C terminal segments of both precursors resemble the glycopeptide moiety of the related mammalian vasopressin precursor, both salmon precursors lack consensus sequences for N-glycosylation.

Amino Acids↗

PubMed1983

Immunocytochemical identification of the mesotocin- and vasotocin-producing systems in the brain of temperate and desert lizard species and their modifications by cold exposure.

Using immunofluorescent techniques, mesotocin (MT) and vasotocin (VT) neurosecretory systems were identified in the brain of different lizards: one temperate species living in southern France and three desert species coming from southern Algeria. In the four species, MT and VT were shown to be synthesized in specific neurons located in the anterior preoptic area (POA), the supraoptic (SON), paraventricular (PVN), and ventromedial (VMN) nuclei. The neurosecretory axons of the POA neurons terminated in the vicinity of the lamina terminalis; in the three desert species, several additional VT fibers extended more rostrally, going into the olfactory bulb. The axons originating in SON, PVN, and VMN ended either in the external zone of the rostral median eminence (ME) near the adenohypophyseal portal vessels, or in the neural lobe of the hypophysis. A short exposure to cold (4 degrees) in some specimens of Lacerta muralis induced a differential response in the dorsal and ventral parts of the PVN. Whereas the dorsal part remained unchanged, the ventral part instead appeared to be essentially composed of small neurons void of secretory granules. Cold exposure also led to a marked accumulation of both MT and VT in the internal zone of the ME, but of only VT in the external ME zone. On the other hand, a conspicuous amount of MT appeared in adenohypophyseal cells.

Animals↗

PubMed1983

The presence of vasotocin and mesotocin in serum and the hypothalamo-neurohypophyseal axis of chick embryos before hatching and in posthatch chicks.

Decreasing hematocrit values were observed in chick embryos, from Day 17 to 1 day posthatching. Arginine vasotocin (AVT) and mesotocin (MT) were determined radioimmunologically in serum, neural lobe, and hypothalamic tissue. Serum levels of AVT and MT were significantly increased on Day 18 of incubation compared to Day 17. Thereafter AVT levels decreased, reaching at hatching levels even below Day 17. Serum MT remained elevated on Day 19, but decreased thereafter to the concentration values of Day 17. The amount of AVT in the preoptic hypothalamus and infundibulum was maximal on Day 19, whereas in the neural lobe the maximum was attained on Day 20. The MT content of the infundibulum and neural lobe reached a maximum plateau on Day 18. These results suggest that a stimulation of the hypothalamo-neurohypophyseal axis in the chick embryo occurs at the end of incubation. A possible causal relation with the observed decreasing hematocrit values is discussed.

Animals↗

PubMed1984

The effect of arginine vasotocin on prostaglandin production of the hen uterus.

The effect of arginine vasotocin (AVT) on prostaglandin (PG) production by the hen uterus (shell gland) in vitro was investigated. It was found that AVT caused uterine contractions as well as PG release from the uteri. In uterine homogenates, which lack the functional integrity for mechanical contractions, AVT also caused an increase in PG biosynthesis. It seems likely that the PG-releasing response to AVT is not a secondary effect of uterine contractions but a specific action of AVT.

Animals↗

PubMed1985

Induction of oviposition in cycling Anolis carolinensis requires a beta-adrenoreceptor blocker and a high dosage of arginine vasotocin.

In a previous study, a high dosage (2.0 micrograms) of arginine vasotocin (AVT), following 10 micrograms of dichloroisoproterenol, induced oviposition in Anolis carolinensis at the end of the breeding season. The present study determined if a lower dosage of AVT (0.25 microgram), comparable to that effective in other lizard species, would induce oviposition in cycling A. carolinensis. Only a high dosage of AVT (2.0 micrograms), following 10 micrograms of dichloroisoproterenol 15 min beforehand, induced oviposition. These results suggest that uterine smooth muscle of A. carolinensis is relatively insensitive to AVT.

Adrenergic beta-Antagonists↗

PubMed1985

Diel variations in arginine vasotocin content of goldfish brain and pituitary: effects of photoperiod and pinealectomy.

Arginine vasotocin (AVT) content was determined in the telencephalon, the hypothalamus, and the pituitary gland of sham-operated and pinealectomized goldfish subjected to 20 degrees and 12/12LD or 24DD photoperiods in winter or spring. The tissues collected at 1000 or 2200 hr were homogenized and extracted in acetic acid. Hypothalamic and telencephalic AVT content, determined by radioimmunoassay, fluctuated throughout the light-dark cycle; AVT content was higher at 2200 than at 1000 hr under the 12/12LD photoperiod. No fluctuations were detected in pituitary AVT content. Telencephalic AVT did not fluctuate under constant darkness, and hypothalamic AVT increased and pituitary AVT decreased compared to the AVT content detected in the 12/12LD groups. No significant effects of pinealectomy or season on AVT levels in the telencephalon, hypothalamus, and the pituitary were evident. The results indicate that AVT content within the preoptico-neurohypophyseal system of the goldfish fluctuate within 24-hr periods and that photoperiod has an effect on the pattern of these fluctuations. The photoperiodic influences do not seem to be mediated by the pineal organ.

Animals↗

PubMed1985

An immunohistochemical study of seasonal changes in luteinizing hormone-releasing hormone and vasotocin in the forebrain and the neurohypophysis of the toad, Bufo japonicus.

Seasonal changes in luteinizing hormone-releasing hormone (LH-RH) and arginine vasotocin (AVT) were examined immunohistochemically in the toad forebrains and neurohypophyses. Strongly immunoreactive (ir-) LH-RH perikarya, from which dense ir-LH-RH fibers project to the median eminence, were localized in the medial septal nucleus and the nucleus of the diagonal band of Broca in the animals captured in the spring and the autumn. While, in the animals collected in the summer, ir-LH-RH perikarya and fibers were sparse, and immunoreactivity in the median eminences was weak. Artificially induced hibernation decreased the density of ir-LH-RH in the median eminence, in contrast with strong immunoreactivity in the control animals kept at room temperature. The amounts of ir-LH-RH in the median eminences of hibernating toads which were captured shortly before the breeding period varied conspicuously among individuals. The median eminences in migrating toads showed relatively weak LH-RH immunoreactivity. After the breeding, the immunoreactivity returned to the strong level that was observed in the spring and the autumn. These seasonal changes in ir-LH-RH seem to correspond to seasonal reproductive activity in this species. However, significant seasonal variations were not found in ir-AVT.

Acclimatization↗

PubMed1986

Arginine vasotocin (AVT) release in relation to uterine contractility in the hen.

The relationship between plasma levels of arginine vasotocin (AVT) and factors associated with increases in uterine contractility was studied in the domestic hen. Plasma AVT levels increased from 3.3 +/- 0.3 microU/ml 15 min before a midsequence oviposition (OP) to 14.8 +/- 0.6 microU/ml at OP and then decreased to 5.2 +/- 0.6 microU/ml 15 min following OP. A ninefold increase in plasma AVT concentration was observed in hens laying a terminal egg of a sequence, which is not immediately followed by ovulation (OV). AVT levels also increased approximately 1 hr before the time of the first ovulation (C1OV) of the next sequence in association with an increase in uterine contractility. When OP was induced 2 hr before an expected OP by intrauterine administration of prostaglandin F2 alpha (PGF2 alpha, 1.0 microgram), plasma AVT levels immediately increased threefold (P less than 0.001) and then returned to basal levels within 30 min. In PGF2 alpha-treated hens AVT levels rose at the expected time of OP (P less than 0.05) in association with an increase in uterine contractility without OP actually occurring. When C1OV was induced by LH-RH (25 micrograms, iv), a small but significant increase of AVT similar to levels during spontaneous C1OV was observed. These results suggest that plasma AVT levels increase with every ovulation and oviposition in the absence of an egg in the uterus and that AVT is released in association with induced ovulation and oviposition.

Animals↗

PubMed1987

Interrelationship between arginine vasotocin, prostaglandin, and uterine contractility in the control of oviposition in the hen (Gallus domesticus).

Uterine electromyographic activity (EMG), plasma concentrations of prostaglandin (PG) F and E, and arginine vasotocin (AVT) were simultaneously measured in relation to PGE2-induced premature oviposition and to indomethacin-blocked oviposition in chickens. The administration of indomethacin (5 mg, im) 3 hr before the predicted time of oviposition delayed egg lay by 8-14 hr, whereas control hens laid eggs at the predicted time. In indomethacin-treated hens increases in uterine EMG activity and plasma concentrations of PGF, PGE, and AVT were not observed at the expected time of oviposition, whereas a marked increase in plasma PGF and AVT occurred during spontaneous oviposition. The intrauterine administration of PGE2 (1 microgram) 3 hr before predicted oviposition induced premature egg lay within 5 min. Premature oviposition was accompanied by significant elevations in both uterine EMG activity and plasma levels of AVT. Changes in plasma levels of PGF and PGE were not observed. When premature oviposition was induced, significant increases in EMG activity and plasma concentrations of PGF and AVT were observed at the expected time of oviposition in the absence of an egg in the uterus. The administration of PGE2 at the predicted time of oviposition in hens pretreated with indomethacin induced oviposition which was accompanied by a significant increase in plasma AVT levels. The results suggest that AVT release is stimulated by uterine contractility in chickens.

Animals↗

PubMed1988

The role of arginine vasotocin and prostaglandin F2 alpha on oviposition and luteolysis in the common snapping turtle Chelydra serpentina.

The administration of arginine vasotocin (AVT) to gravid snapping turtles with steroidogenically active corpora lutea and high plasma progesterone concentration (1480 +/- 155 pg/ml) did not trigger oviposition, whereas 12 days after ovulation when luteolysis occurred and plasma progesterone concentration was low (570 +/- 78 pg/ml), treatment with AVT caused oviposition. Controls with high plasma progesterone concentration (1605 +/- 185 pg/ml) oviposited 15-23 days after ovulation when plasma progesterone concentration dropped to 201 +/- 35 pg/ml. Deluteinization-induced oviposition was initiated 15 hr after surgery and was completed by 30 hr. Oviposition of complete clutches occurred and was correlated with a significant drop in plasma progesterone. Sham-operated turtles did not exhibit oviposition and no significant change in progesterone concentration was observed. A single injection of prostaglandin F2 alpha (PGF) in recently ovulated turtles induced early luteolysis and a significant decrease in plasma progesterone concentration after 24-30 hr. A single administration of PGF caused the disappearance of steroidogenic features such as the smooth endoplasmic reticulum and mitochondria with tubular cristae 48 hr later. Also PGF triggered the invasion of a hyaline-like material from the luteal theca into the luteal cell mass which eventually induced luteolysis. The role of AVT, PGF, and progesterone in relation to egg retention and oviposition is discussed.

Animals↗

PubMed1988

Coexistence of corticotropin-releasing factor-like immunoreactivity and vasotocin in perikarya of the preoptic nucleus in the eel.

A corticotropin-releasing factor (CRF)-like system has been identified in eels (Anguilla anguilla, A. rostrata, and A. japonica) with immunocytochemical techniques. Immunoreactive perikarya were located in the preoptic area, in magno- and parvocellular regions of the preoptic nucleus. Fine fibers reached the pituitary and terminated in the neurohypophysis close to the corticotropic cells of the rostral pars distalis and caudally close to the melanocorticotropic cells of the intermediate lobe. Double immunostainings revealed the presence of three subpopulations of perikarya: one population containing only CRF, a second containing only arginine vasotocin (VT), and a third one containing both CRF and VT. This coexistence of CRF and VT was also demonstrated by comparing adjacent sections stained with anti-CRF and anti-VT, respectively. Because antisera used in the present work were carefully absorbed, these data strongly suggest that CRF and VT coexist in some perikarya, at least in the animals studied.

Anguilla↗

PubMed1988

Plasma levels of immunoreactive mesotocin and vasotocin during oviposition in chickens: relationship to oxytocic action of the peptides in vitro and peptide interaction with myometrial membrane binding sites.

Plasma concentrations of immunoreactive vasotocin (AVT) and mesotocin (MT) were measured periodically before and subsequent to spontaneous oviposition in conscious chickens. The concentrations of AVT and MT approximately an hour prior to oviposition were 5.2 +/- 1.1 microU/ml and 14.7 +/- 5.1 pg/ml, respectively. Plasma AVT levels increased abruptly at oviposition (25.1 +/- 3.3 microU/ml) and decreased to 5.0 +/- 0.6 microU/ml within 30 min postoviposition. Significant changes in MT were not observed. The data indicate that AVT is selectively released during oviposition. The uterus was removed immediately after oviposition and the oxytocic potencies of several peptides were tested on muscle strips in vitro. The order of oxytocic potencies was AVT greater than or equal to arginine vasopressin (AVP) much greater than MT = pressinoic acid. Partially purified membranes were prepared from separate portions of the uteri used in the oxytocic assay. [3H]arginine8 vasopressin, [3H]AVP, bound to membranes saturably (Bmax = 17 fmol/mg protein) and with high affinity (Kd = 0.7 nM). The rank order of potency of the peptides in displacing [3H]AVP from the binding sites was the same as in the oxytocic assay which suggests that the [3H]AVP binding sites in uterine membranes represent physiological receptors that interact with AVT during oviposition.

Animals↗

PubMed1988

Arginine vasotocin from the pituitary gland of the lamprey (Petromyzon marinus): isolation and amino acid sequence.

Arginine vasotocin (AVT) was isolated from extracts of sea lamprey pituitary glands (Petromyzon marinus). The amino acid sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Arg-Gly-NH2 is identical to the molecule isolated from teleosts and tetrapods. The total yield was estimated to be 9.6 pmol per gland. No evidence could be found for the existence of a second neurohypophyseal nonapeptide in the lamprey pituitary.

Amino Acid Sequence↗