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

The effect of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), and oxytocin (OT) on cAMP and cGMP accumulation was investigated in LLC-PK1 kidney epithelial cells. The addition of ANP, AVP, and OT to intact cells produced a time- and concentration-dependent increase in cGMP accumulation. ANP produced a 1.7-fold increase in cGMP at 10 pM and a maximal 28-fold increase in cGMP at 1 microM. ANP had no effect on basal or AVP-induced stimulation of cAMP accumulation. OT was 10-fold more potent than AVP at increasing cGMP levels, producing a 2.1-fold increase in cGMP at 0.1 nM, whereas AVP was 100-fold more potent at increasing cAMP levels. At a concentration of 1 microM, AVP and OT produced a maximal 12 to 14-fold increase in cGMP, while OT and AVP produced 50- and 90-fold increase in cAMP, respectively. The selective OT agonist [Thr4, Gly7]oxytocin was very effective at increasing cGMP, but not at increasing cAMP levels. The V2-vasopressin agonist [deamino-Pen1,Val4, D-Arg8]vasopressin did not increase cGMP levels, but produced a 20-fold increase in cAMP levels. The addition of ANP together with either AVP or OT produced an additive increase in cGMP content. Simultaneous addition of AVP and OT did not lead to a greater increase in cAMP or cGMP levels. These results suggest that the AVP- and OT-induced increase in cGMP is mediated by OT receptors, whereas the increase in cAMP is probably mediated by vasopressin receptors. ANP increased the activity of particulate guanylate cyclase by 6-fold, while AVP and OT has no effect on particulate guanylate cyclase activity. The relatively selective inhibitor of soluble guanylate cyclase, methylene blue, had no effect on the ANP-induced increase in cGMP content in intact cells, but produced a 50% inhibition of the increase in cGMP by AVP and OT. Methylene blue did not alter the stimulation of cAMP by AVP or OT. These results demonstrate that ANP, AVP, and OT increase cGMP in LLC-PK1 kidney epithelial cells. The increase in cGMP by ANP is mediated by particulate guanylate cyclase, whereas AVP and OT probably increase cGMP by interacting with OT receptors coupled to soluble guanylate cyclase.
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PMID:Atrial natriuretic peptide, oxytocin, and vasopressin increase guanosine 3',5'-monophosphate in LLC-PK1 kidney epithelial cells. 289 98

The effects of phosphodiesterase inhibitors, an activator and an inhibitor of guanylyl cyclase, and cAMP and cGMP analogs on oxytocin-induced contractions have been studied in the testicular capsule of rats. The nonspecific phosphodiesterase inhibitors, theophylline and caffeine, attenuated the oxytocin-induced contractions via mechanisms that seem to be related to an increase in cAMP levels, since a similar effect was produced by dibutyryl cAMP. Sodium nitroprusside facilitated oxytocin-induced contractions. This effect was mimicked by dibutyryl cGMP. Methylene blue, an inhibitor of soluble guanylyl cyclase, decreased oxytocin-induced contractions, which suggests an involvement of guanylyl cyclase in the oxytocin effect. These results suggest that cAMP modulates the contraction and that cGMP, contrary to what happens in most smooth muscles, could participate in oxytocin-induced contractions in the testicular capsule of rats.
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PMID:Role of cyclic nucleotides in contraction induced by oxytocin in the testicular capsule of the rat in vitro. 899 Apr 88

A dose of oxytocin (50 ng i.c.v.) that induces penile erection and yawning, increased the concentration of NO2- from 0.98 +/- 0.29 to 4.2 +/- 0.79 microM and of NO3- from 5.6 +/- 0.33 to 12.03 +/- 0.99 microM in the dialysate from the paraventricular nucleus of the hypothalamus of male rats, as measured by in vivo microdialysis. NO2- concentration was also increased by [Thr4, Gly7]-oxytocin (100 ng i.c.v. and oxytocin(8) (1 microgram i.c.v.) which also induced penile erection and yawning, but not by oxytocin(1-6) (1 microgram i.c.v.) or oxytocin (7-9) 1 microgram i.c.v.), which were unable to induce these behavioral responses. The oxytocin effect on NO2 concentration, penile erection and yawning was prevented by the oxytocin receptor antagonist. d(CH2)5,Tyr(Me)-Orn8-vasotocin (1 microgram i.e.v.) or by the nitric oxide synthase inhibitor, NG-nitro-1-arginine methyl ester (200 micrograms i.c.v.), but not by the dopamine receptor antagonist, haloperidol (0.5 mg/kg i.p.). The nitric oxide scavenger, hemoglobin (200 micrograms i.c.v.), prevented oxytocin-induced NO2- concentration increase, but was unable to prevent penile erection and yawning. Methylene blue (300 micrograms i.c.v.) an inhibitor of guanylate cyclase, was ineffective on oxytocin-induced NO2- concentration increase, but prevented the behavioral responses. The results suggest that oxytocin induces penile erection and yawning by increasing nitric oxide synthase activity in the cell bodies of oxytocinergic neurons projecting to extra-hypothalamic brain areas and mediating the behavioral responses.
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PMID:Oxytocin increases nitric oxide production in the paraventricular nucleus of the hypothalamus of male rats: correlation with penile erection and yawning. 917 53