Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, it was shown that in LLC-PK1 kidney epithelial cells hormones such as vasopressin or oxytocin increase cyclic GMP in a receptor-mediated and L-arginine-dependent manner. In the present study, the possible existence of cross-tolerance to vasopressin and oxytocin was investigated in nitrate-tolerant LLC-PK1 cells. Pretreatment with 1 mM glyceryl trinitrate for 3 h decreased cyclic GMP stimulation by 1 microM vasopressin and 1 microM oxytocin by 49% and 54%, respectively. Under the same conditions, cyclic GMP stimulation at 1 microM sodium nitroprusside was diminished by 56% whereas the cyclic GMP response to 100 microM glyceryl trinitrate was virtually abolished. Our results demonstrate that a substantial degree of cross-tolerance to L-arginine-dependent guanylate cyclase activators occurs in nitrate-pretreated nonvascular cells which may be due to glyceryl trinitrate-induced desensitization of soluble guanylate cyclase.
 ...
PMID:Cross-tolerance to L-arginine-dependent guanylate cyclase activators in nitrate-tolerant LLC-PK1 kidney epithelial cells. 197 70

A low dose of apomorphine (80 micrograms/kg s.c.), a mixed D1/D2 agonist that induces penile erection and yawning, increased the concentration of NO2-from 1.12 +/- 0.45 microM to 3.8 +/- 0.75 microM and NO3-from 5.53 +/- 0.82 to 11.25 +/- 2.30 microM in the dialysate collected from the paraventricular nucleus of the hypothalamus of male rats by in vivo microdialysis. The NO2-concentration was also increased by LY 171555 (50 micrograms/kg s.c.), a D2 agonist that induces penile erection and yawning, but not by SKF 38393 (5 mg/kg s.c.), a D1 agonist with no effect on these responses. Conversely, apomorphine's effect on NO2-was prevented by haloperidol (0.5 mg/kg i.p.), a mixed D1/D2 antagonist and L-sulpiride (25 mg/kg i.p.), a D2 antagonist, but not by the D1 agonist SCH 23390 (50 micrograms/kg s.c.), although all three compounds prevented penile erection and yawning. The apomorphine effect on NO2-, penile erection and yawning was also prevented by the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (200 micrograms i.c.v.). The nitric oxide scavenger haemoglobin (200 micrograms i.c.v.) also prevented the NO2-increase, but was ineffective against penile erection and yawning. In contrast, the oxytocin antagonist d(CH2)5Tyr(Me)-Orn8-vasotocin (1 microgram i.c.v.) and the guanylate cyclase inhibitor methylene blue (300 micrograms i.c.v.) had no effect on the NO2-increase, but did prevent the behavioural responses. We infer from this that dopamine agonists induce penile erection and yawning by acting on D2 receptors that increase nitric oxide synthase activity in the cell bodies of paraventricular oxytocinergic neurons projecting to extra-hypothalamic brain areas.
 ...
PMID:Dopamine agonists increase nitric oxide production in the paraventricular nucleus of the hypothalamus: correlation with penile erection and yawning. 892 Dec 95

The possible involvement of nitric oxide in the prevention by morphine of apomorphine- and oxytocin-induced penile erection and yawning was investigated by measuring the concentration of NO2- and NO3- in the dialysate obtained with a vertical microdialysis probe implanted in the paraventricular nucleus of the hypothalamus of male rats. Either apomorphine (80 micrograms/kg s.c.) or oxytocin (30 ng i.c.v.) increased significantly basal NO2- and NO3- concentration in the paraventricular dialysate, penile erection and yawning. Morphine (1.5 and 10 mg/kg i.p.) prevented dose-dependently either apomorphine or oxytocin responses when given 15 min before apomorphine or oxytocin. Prevention by morphine of apomorphine and oxytocin responses was abolished by naloxone (3 mg/kg i.p.) given 15 min before morphine. Morphine prevented apomorphine and oxytocin responses also when given in the lateral ventricles or directly in the paraventricular nucleus. In contrast, the selective agonist of the kappa opioid receptor subtype U-69,593 was found to be ineffective. The present results confirm previous findings showing that morphine acts through mu receptors in the paraventricular nucleus to prevent apomorphine and oxytocin-induced penile erection and yawning and suggest that this morphine effect is mediated by a decreased activity of nitric oxide in the paraventricular nucleus of the hypothalamus.
 ...
PMID:Prevention by morphine of apomorphine- and oxytocin-induced penile erection and yawning: involvement of nitric oxide. 915 Dec 98

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.
 ...
PMID:Oxytocin increases nitric oxide production in the paraventricular nucleus of the hypothalamus of male rats: correlation with penile erection and yawning. 917 53

1. Recent experimental evidence has shown that nitric oxide (NO) plays an important role in the expression of penile erection and yawning and that this molecule has to be added to the list of the best known neurotransmitters and neuropeptides involved in this symptomatology. 2. This was first suggested by the ability of NO synthase inhibitors injected in the lateral ventricles (i.c.v.) or in the paraventricular nucleus of the hypothalamus (PVN) to prevent these behavioral responses induced by dopamine agonists, oxytocin and NMDA. The inhibitory effect of NO synthase inhibitors was not observed when these compounds were injected concomitantly with L-arginine, the precursor of NO. Most important, this hypothalamic nucleus is one of the richest brain areas of NO synthase and also the brain site where dopamine, NMDA and oxytocin act to induce penile erection and yawning by activating central NO synthase containing oxytocinergic neurons. 3. NO synthase inhibitors given i.c.v. but not in the PVN prevent also penile erection and yawning induced by ACTH and serotonin1c agonists, which induce these responses by acting with mechanisms unrelated to oxytocinergic transmission. 4. Dopamine agonists, NMDA and oxytocin increase NO production in the PVN at doses that induce penile erection and yawning, as determined by measuring the concentration of NO2- and NO3- in the dialyzate obtained with a vertical probe implanted in the PVN by in vivo microdialysis. 5. NO donors, such as nitroglycerin, sodium nitroprusside and hydroxylamine, induce penile erection and yawning indistinguishable from those induced by oxytocin, dopamine agonists or NMDA when injected in the PVN. The NO donor response was prevented by the i.c.v. injection of the oxytocin receptor antagonist d(CH2)5-Tyr(Me)-Orn8-vasotocin, indicating that these compounds also induce penile erection and yawning by activating oxytocinergic transmission. 6. Finally, guanylate cyclase inhibitors (i.e. methylene blue and LY 83583) and hemoglobin injected in the PVN do not prevent drug-induced penile erection and yawning, nor 8-Br-cGMP injected in the PVN induces these behavioral responses suggesting that the mechanism by means of which endogenous or NO donor-derived NO facilitates oxytocinergic transmission to induce penile erection and yawning is not related to the activation of guanylate cyclase. Furthermore, since hemoglobin, in spite of its ability to prevent drug-induced NO production in the PVN, does not prevent penile erection and yawning, it is likely that NO acts as an intracellular rather than an intercellular modulator in the PVN neurons in which is formed to facilitate the expression of these behavioral responses.
 ...
PMID:Role of central nitric oxide in the control of penile erection and yawning. 938 Jul 88

A dose of apomorphine or oxytocin that induces penile erection and yawning increases nitric oxide production in the paraventricular nucleus of the hypothalamus, as determined by the increase in NO2- and NO3- concentration induced by these substances in the paraventricular dialysate obtained from male rats. All the above responses were prevented by a dose of omega-conotoxin-GVIA as low as 5 ng. This potent inhibitor of N-type Ca2+ channels was injected into the paraventricular nucleus 15 min before apomorphine (50 ng) or oxytocin (10 ng). In contrast, omega-conotoxin was ineffective when the above responses were induced by N-methyl-D-aspartic acid (50 ng). The peptide toxin (5 ng) was also ineffective on the penile erection and yawning induced by the nitric oxide donors sodium nitroprusside (50 microg) or hydroxylamine (50 microg), injected into the paraventricular nucleus. The present results suggest that omega-conotoxin-sensitive Ca2+ channels are involved in the activation of nitric oxide synthase, penile erection and yawning induced by apomorphine and oxytocin, but not by N-methyl-D-aspartic acid, at the paraventricular level.
 ...
PMID:Different effects of omega-conotoxin on penile erection, yawning and paraventricular nitric oxide in male rats. 983 Dec 88

Our hypothesis is that oxytocin (OT) causes natriuresis by activation of renal NO synthase that releases NO followed by cGMP that mediates the natriuresis. To test this hypothesis, an inhibitor of NO synthase, L-nitroarginine methyl ester (NAME), was injected into male rats. Blockade of NO release by NAME had no effect on natriuresis induced by atrial natriuretic peptide (ANP). This natriuresis presumably is caused by cGMP because ANP also activates guanylyl cyclase, which synthesizes cGMP from GTP. The 18-fold increase in sodium (Na+) excretion induced by OT (1 microgram) was accompanied by an increase in urinary cGMP and preceded by 20 min a 20-fold increase in NO3- excretion. NAME almost completely inhibited OT-induced natriuresis and increased NO3- excretion; however, when the dose of OT was increased 10-fold, a dose that markedly increases plasma ANP concentrations, NAME only partly inhibited the natriuresis. We conclude that the natriuretic action of OT is caused by a dual action: generation of NO leading to increased cGMP and at higher doses release of ANP that also releases cGMP. OT-induced natriuresis is caused mainly by decreased tubular Na+ reabsorption mediated by cGMP. In contrast to ANP that releases cGMP in the renal vessels and the tubules, OT acts on its receptors on NOergic cells demonstrated in the macula densa and proximal tubules to release cGMP that closes Na+ channels. Both ANP- and OT-induced kaliuresis also appear to be mediated by cGMP. We conclude that cGMP mediates natriuresis and kaliuresis induced by both ANP and OT.
 ...
PMID:Atrial natriuretic peptide and oxytocin induce natriuresis by release of cGMP. 987 9

In neonatal calves besides adaptations in organ function there are marked metabolic and endocrine changes. The growth hormone (GH)-insulin-like growth factor (IGF) axis is basically functioning, but needs maturation. Various metabolic and endocrine traits do not exhibit marked ontogenetic changes after the first week of life, but others remain different from the adult stage. Thus, plasma oxytocin or an oxytocin-like substance and nitrate concentrations are elevated for months. The ability to digest colostrum (C) and milk involves great alterations in structure and function of the gastrointestinal (GI) tract. C intake is important for passive immunity, provision of nutrients, minerals and vitamins, and contains biologically active substances. IGF-I, present in C in high amounts, appears to enhance GI tract development and function. For sufficient absorption not only of immunoglobulins, but also of fatty acids and fat-soluble vitamins, C should be ingested immediately after birth. The amino acid pattern and the glutamine/glutamate ratio depends greatly on whether C is fed or not. Effects on insulin, IGF-I, and IGF binding proteins depend on time-point and amounts of C fed. After the colostral period calves are almost exclusively fed milk and milk substitutes or weaned. Low iron intake, required for the production of pale meat, besides anemia causes metabolic and endocrine adaptations, such as enhanced insulin-dependent glucose utilization and appears to reduce IGF-I responses to GH. Metabolic and endocrine changes, such as insulin resistance and disturbed glucose metabolism, can be observed in part in association with high feeding intensity in veal calves.
 ...
PMID:Endocrine and metabolic aspects in milk-fed calves. 1052 25

A study of the effect of nicorandil (N-2-(hydroxyethyl)nicotinamide nitrate, CAS 65141-46-0), a potassium channel and guanylatecyclase activator, upon preparations of rat was deferens and uterus, and guinea pig ileum was performed. Nicorandil does not modify rat isolated was deferens responses to noradrenaline (norepinephrine) and potassium. The drug exerts a non-competitive antagonist effect upon rat isolated uterus response to serotonin, histamine, oxytocin, and, at high concentrations, inhibits guinea-pig isolated ileum responses to acetylcholine, histamine, 4-aminopyridine and potassium.
 ...
PMID:Effect of nicorandil upon different guinea-pig and rat isolated organ preparations in vitro. 1080 Jun 32

In male rats, noncontact erections occur concomitantly with an increase in NO2- and NO3- in the paraventricular nucleus of the hypothalamus (PVN). In the present study, both responses were reduced by the blockade of PVN excitatory amino acid receptors by dizocilpine, (+)-MK-801(1 and 5 microg), but not by 6-cyano-7-nitro-quinoxaline-2,3-dione (5 microg) or (+)-2-amino-4-phosphono-butanoic acid (5 microg). Also ineffective when injected into the PVN were the dopamine antagonists SCH 23390 (5 microg), S(+)-raclopride (10 microg), and cis-flupenthixol (10 microg), and the oxytocin antagonist d(CH2)5Tyr(Me)2-Om8-vasotocin (1 microg). However, when the last was given into the lateral ventricles, it reduced noncontact erections without modifying NO2- and NO3- increases. These results suggest that excitatory amino acid transmission increases in the PVN during noncontact erections. This may contribute to increased NO production in the PVN, and it may activate oxytocin neurons mediating this sexual response.
 ...
PMID:Effect of excitatory amino acid, dopamine, and oxytocin receptor antagonists on noncontact penile erections and paraventricular nitric oxide production in male rats. 1095 43


1 2 Next >>