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Biomedical subjects

A Argiolas

Publications and source records attributed to A Argiolas.

At least 55 records · Page 3Linked to original sources
PubMed1995

Oxytocin in human intrauterine tissues at parturition.

The recent detection of oxytocin (OT) mRNA in human gestational tissues suggests that OT may be locally synthesized and released to act on the uterus as a local mediator in the mechanism of parturition. In order to investigate this possibility the OT immunoreactive (I.R.) content was examined directly in placental decidua and amniochorial membranes after term and preterm delivery and in their culture media at term gestation. I.R.OT concentrations were also measured in maternal, retroplacental and umbilical plasma as well as in amniotic fluid in the presence or the absence of labour. Low I.R.OT concentrations (below 15 fmol g-1 wet tissue) were found in both amniochorial membranes and placental decidua. Moreover, whereas in amniochorion they were higher (P < 0.05) after preterm than term spontaneous parturition, in decidua they were higher (P < 0.05) after term than preterm vaginal delivery. Detectable amounts (below 15 fmol g-1 wet tissue per h) of I.R.OT were also found in culture media from explants of the above tissues. Among all the examined maternal and fetal fluids a rise in I.R.OT content at parturition was detected only in the amniotic liquor (P < 0.05). These findings suggest that I.R.OT concentrations in intrauterine tissues are very low; however, considering that OT is the most potent endogenous uterotonic agent, OT as such concentrations might play a paracrine function in the biochemical events leading to human parturition. Therefore, a role for amniotic OT in parturition can not be excluded.

Adult↗
PubMed1995

Oxytocin-induced penile erection. Role of nitric oxide.

In order to investigate the mechanism of action by which oxytocin induces penile erection, the effect of NG-nitro-L-arginine methyl ester (NAME) and NG-monomethyl-L-arginine (NMMA), inhibitors of nitric oxide (NO) synthase, injected into the paraventricular nucleus of the hypothalamus (PVN) on the response to oxytocin injected into the PVN was studied in male rats. NAME and NMMA, but not NG-mono-methyl-D-arginine (D-NMMA), which does not inhibit NO-synthase, prevented in a dose-dependent manner the response to oxytocin. NAME was 4-5 times more potent than NMMA. NAME prevention of the oxytocin effect was not observed when NAME was given together with L-arginine but not with D-arginine. Oxytocin-induced penile erection was prevented by the oxytocin antagonist d(CH2)5Tyr(Me)-Orn8-vasotocin and by methylene blue, an inhibitor of guanylate cyclase, but not reduced hemoglobin, a NO scavenger, given intracerebroventricularly (i.c.v.). In contrast, both methylene blue and hemoglobin were ineffective when injected into the PVN, unlike d(CH2)5Tyr(Me)-Orn8-vasotocin. Penile erection was induced also by sodium nitroprusside and hydroxylamine, two NO donors, injected into the PVN. Like the oxytocin effect, the NO donor response was prevented by i.c.v. d(CH2)5Tyr(Me)-Orn8-vasotocin and methylene blue, but not hemoglobin. In contrast, the three compounds were ineffective in preventing the NO donor response when injected into the PVN. The present results suggest that oxytocin induces penile erection by activating NO synthase in the PVN. NO in turn activates oxytocinergic neurons projecting to extra-hypothalamic areas that control the expression of this male sexual function by a guanosine cyclic 3':5'-monophosphate (cGMP) independent mechanism at least in the PVN.

Animals↗
PubMed1994

Nitric oxide synthase inhibitors prevent N-methyl-D-aspartic acid-induced penile erection and yawning in male rats.

The effect of NG-nitro-L-arginine methylester (NAME) and N-mono-methyl-L-arginine (NMMA), inhibitors of nitric oxide (NO) synthase on penile erection and yawning induced by N-methyl-D-aspartic acid (NMDA) injected in the paraventricular nucleus of the hypothalamus (PVN) was studied in male rats. NAME (75-150 micrograms) and NMMA (250-500 micrograms), but not N-monomethyl-D-arginine (D-NMMA)(250-500 micrograms) prevented both responses in a dose-dependent manner when given intracerebroventricularly (i.c.v.) 15 min before NMDA (50 ng). NMDA-induced penile erection and yawning was also prevented by the guanylate cyclase inhibitor methylene blue (200-400 micrograms i.c.v.), but not by the NO scavenger methemoglobin (50-100 micrograms i.c.v.). NAME (10-20 micrograms), but not Methylene blue or methemoglobin (10-20 micrograms), prevented NMDA-induced responses also when injected in the PVN 15 min before NMDA. The present results suggest that NMDA-induced penile erection and yawning is mediated by an increased NO synthesis in the PVN.

Amino Acid Oxidoreductases↗
PubMed1994

Penile erection and yawning induced by 5-HT1C receptor agonists in male rats: relationship with dopaminergic and oxytocinergic transmission.

1-(3-Chlorophenyl)piperazine (m-CPP) (0.1-4 mg/kg s.c.) and N-(3-trifluoromethylphenyl)-piperazine (TFMPP) (0.5-4 mg/kg s.c.), 5-HT1C receptor agonists, but not 8-hydroxy-dipropylamino-tetralin (8-OH-DPAT) (0.1 and 0.2 mg/kg s.c.), a 5-HT1A receptor agonist, induced penile erection and yawning with a U-inverted dose-response curve in male rats. The maximal effect was found with 0.5 mg/kg s.c. of m-CPP and with 1 mg/kg s.c. of TFMPP. The m-CPP (0.5 mg/kg s.c.) and TFMPP (1 mg/kg s.c.) responses were prevented by mianserin (0.2 mg/kg s.c.) and by ritanserin (1 mg/kg s.c.) given 15 min before m-CPP and TFMPP. In contrast, m-CPP- or TFMPP-induced penile erection and yawning were not antagonized by haloperidol (0.1 mg/kg s.c.) or by [d(CH2)5Tyr(Me)2,Orn8]vasotocin (5 micrograms i.c.v.). Apomorphine- and oxytocin-induced penile erection, but not yawning, was also antagonized by mianserin and less effectively by ritanserin. The results suggest that 5-HT1C receptor agonist-induced penile erection and yawning are not mediated by increased dopaminergic and/or oxytocinergic transmission, and raise the possibility that a neuronal dopamine-oxytocin-5-HT link is involved in the control of penile erection and not necessarily of yawning in male rats.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Nitric oxide is a central mediator of penile erection.

In order to evaluate a possible role of brain nitric oxide (NO) on the control of penile erection, the effect of nitroglycerin, that is thought to act by producing NO, was studied on spontaneous penile erection in male rats. In addition the effect of drugs that prevent NO formation and/or activity such as NG-nitro-L-arginine methyl ester (NAME) and methylene blue, on N-methyl-D-aspartic acid (NMDA)-, apomorphine- and oxytocin-induced penile erection was also studied. Nitroglycerin induced penile erection in a dose-dependent manner when given intracerebroventricularly (i.c.v.) (33-99 micrograms) or in the paraventricular nucleus of the hypothalamus (0.8-3.3 micrograms). Nitroglycerin-induced penile erection was prevented by the guanylate cyclase inhibitor methylene blue injected i.c.v. (200-400 micrograms) but not in the paraventricular nucleus of the hypothalamus (10-20 micrograms). Conversely, NMDA-, apomorphine- and oxytocin-induced penile erection was prevented by NAME (150 micrograms) or methylene blue (400 micrograms) given i.c.v. NAME (20 micrograms), but not methylene blue (20 micrograms), was effective in preventing the behavioral response also when injected in the paraventricular nucleus. The present results suggest that NO is a common mediator of several neurotransmitters involved in the control of this primary male sexual function.

Animals↗
PubMed1994

Prevention by NG-nitro-L-arginine methyl ester of apomorphine- and oxytocin-induced penile erection and yawning: site of action in the brain.

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.

Animals↗
PubMed1994

Penile erection and yawning induced by paraventricular NMDA injection in male rats are mediated by oxytocin.

The effect of N-methyl-D-aspartic acid (NMDA), (+-)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA), or (+-)-trans-1-amino-1,3-cyclo-pentanedicarboxylic acid (ACPD) (5-60 ng in 0.3 microliter of saline) microinjected in the paraventricular nucleus of the hypothalamus on penile erection and yawning was studied in male rats. NMDA induced both penile erection and yawning in a dose-dependent manner. AMPA and ACPD also induced penile erection but less potently than NMDA, but were ineffective in causing yawning. NMDA effect on penile erection and yawning was prevented by (+)-MK-801 (0.05-0.1 mg/kg IP, 10 min before NMDA), by the oxytocin antagonist d(CH2)5Tyr(Me)-Orn8- vasotocin (50-100 ng ICV 10 min before NMDA), but not by haloperidol (0.1-0.5 mg/kg IP 10 min before NMDA). The results suggest that NMDA induces penile erection and yawning by increasing oxytocinergic transmission by acting in the paraventricular nucleus of the hypothalamus.

Animals↗
PubMed1994

Apomorphine-and oxytocin-induced penile erection and yawning in intact and castrated male rats: effect of sexual steroids.

The effect of apomorphine (80 micrograms/kg s.c.) and oxytocin (30 ng i.c.v.) on penile erection and yawning was studied in intact and castrated male rats. In castrated rats both apomorphine and oxytocin responses were abolished. In these animals, testosterone (100 microgramS/kg s.c. once a day for 3 days), restored penile erection while estradiol benzoate (10 micrograms/kg s.c. once a day for 3 days) restored yawning induced by both compounds. 5-Dihydrotestosterone (DHT) or progesterone (each at a dose of 100 micrograms/kg s.c. once a day for 3 days) were ineffective. Given together, estradiol benzoate and DHT partially restored apomorphine- and oxytocin-induced yawning and penile erection, whereas estradiol benzoate and progesterone restored only yawning. Estradiol benzoate-induced recovery of yawning was prevented by the antiestrogen tamoxifen (1 mg/kg s.c. once a day for 3 days). In intact rats, progesterone increased and estradiol benzoate decreased apomorphine- and oxytocin-induced yawning without modifying penile erection, although oxytocin-induced yawning was prevented much less by estradiol benzoate than that induced by apomorphine. Testosterone or DHT were ineffective on both responses. Estradiol benzoate inhibition of apomorphine- and oxytocin-induced yawning was prevented by tamoxifen, which per se failed to modify apomorphine and oxytocin responses, as well as by testosterone or progesterone. The present results suggest that apomorphine- and oxytocin-induced penile erection and yawning are endocrine-dependent and differentially modulated by sexual steroids, suggesting that the mechanisms controlling the two behaviors are different even though they are often associated.

Animals↗
PubMed1993

Nitric oxide synthase inhibitors prevent apomorphine- and oxytocin-induced penile erection and yawning in male rats.

The effect of NG-nitro-L-arginine methyl ester and NG-monomethyl-L-arginine, two inhibitors of nitric oxide synthase, on apomorphine- and oxytocin-induced penile erection and yawning, was studied in male rats after intravenous and intracerebroventricular administration. Both compounds prevented dose-dependently apomorphine and oxytocin responses, when given systemically (5-50 mg/kg) or centrally (30-500 micrograms per rat), but NG-nitro-L-arginine methyl ester was about 5 times more potent than NG-monomethyl-L-arginine. The D-isomer of NG-monomethyl-L-arginine, which does not inhibit nitric oxide synthase, was ineffective. The results suggest that central nitric oxide is involved in the expression of penile erection and yawning induced by apomorphine and oxytocin.

Amino Acid Oxidoreductases↗
PubMed1993

alpha-Melanocyte-stimulating hormone during human perinatal life.

To obtain information on human pituitary intermediate lobe activity throughout the perinatal period, plasma alpha MSH immunoreactivity (IR) was measured in 106 newborns at delivery and during the first week of postnatal life. Subjects were divided into groups according to gestational age at birth, mode of parturition, and antenatal state of health. Plasma alpha MSH IR decreased progressively from severe preterm to fullterm neonates born by vaginal delivery (VD; P < 0.001) or cesarean section (CS) with and without prenatal distress (P < or = 0.001 in both cases). alpha MSH IR was due, in all studied conditions, to three major forms: desacetyl alpha MSH, alpha MSH, and diacetyl alpha MSH. Desacetyl alpha MSH was always the most represented form, but it decreased from 75-80% of the total in severe premature to 40-45% in mature infants. In term neonates, total alpha MSH IR values were higher in subjects born by normal VD than by elective CS (P < or = 0.05), in complicated than in normal VD (P < or = 0.01), and in CS performed because of fetal distress than in elective CS (P < or = 0.01). No significant difference was detectable in mature subjects in the percentages of the three alpha MSH forms in relation to the mode of delivery and fetal state during antenatal life or at parturition. Twelve hours after birth, total alpha MSH IR significantly decreased in all groups of term newborns, reaching a plateau of 0.8-1.4 pmol/L. In premature infants, similar concentrations were detectable by the fourth postnatal day. We conclude that 1) alpha MSH IR intermediate lobe secretion progressively decreases throughout the third trimester of pregnancy; 2) stress, including that pertinent to parturition, stimulates alpha MSH IR release; and 3) pituitary intermediate lobe activity declines shortly after birth independently of the maturity reached by the fetus, the mode of parturition, and the presence of antenatal chronic distress, although the process is slightly retarded in premature newborns.

Cesarean Section↗
PubMed1993

Evidence of chromosomal fragile sites in schizophrenic patients.

Chromosomal fragility and other chromosomal abnormalities were frequently observed in subjects with neuropsychiatric disorders, such as fragile X syndrome, autism or schizophrenia, but only for the first one the fragility is accepted to be associated to a specific pathology, so that it is used as a diagnostic marker. In this study the authors analyzed 50 schizophrenic males, searching for the rare fragile sites or other aberrations with the method suitable for fra(X) detection. Chromosomes from schizophrenic patients resulted more fragile than those from normal controls, especially chromosome 9. The authors discuss the implications of a possible association of these data with the aetiopathogenesis of schizophrenic syndrome.

Chromosome Fragile Sites↗
PubMed1992

Effect of excitatory amino acid receptor antagonists on apomorphine-, oxytocin- and ACTH-induced penile erection and yawning in male rats.

The effect of excitatory amino acid receptor antagonists, (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclo-hepten-5, 10-imine hydrogen maleate ((+)-MK-801), (+/-)-3-(2-carboxy-piperazin-4-yl)-propyl-1-phosphonic acid (CPP), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and (+/-)-2-amino-4-phosphonobutanoic acid (AP-4), on penile erection and yawning induced by subcutaneous apomorphine (80 micrograms/kg), intracerebroventricular (i.c.v.) oxytocin (30 ng) and adrenocorticotropin (ACTH)-(1-24) (10 micrograms) was studied in male rats. Intraperitoneal (0.1-0.4 mg/kg) and i.c.v. (10-50 micrograms) (+)-MK-801 prevented dose dependently the penile erection and yawning induced by the three drugs. The (+)-MK-801 effect coincided with the appearance of head weaving, body rolling, hyperlocomotion and ataxia. Haloperidol (0.5 mg/kg i.p.) antagonized the prevention by (+)-MK-801 of oxytocin responses. Penile erection but not yawning was also prevented by high, but not low doses of CPP and CNQX, which impaired motor performance, AP-4 was ineffective at all doses tested. The above compounds were ineffective when injected into the paraventricular nucleus of the hypothalamus, the brain area where apomorphine and oxytocin act to induce penile erection and yawning. The results suggest that excitatory amino acid transmission is not involved in the expression of penile erection and yawning induced by the above compounds.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1992

Hippocampal oxytocin mediates apomorphine-induced penile erection and yawning.

Repeated episodes of penile erection and yawning can be induced in male rats either by low doses of the dopaminergic agonist apomorphine or by oxytocin given systematically or into a lateral ventricle (ICV), respectively, or after microinjection of the two substances directly in the paraventricular nucleus (PVN) of the hypothalamus. These behavioral responses are prevented in a dose-dependent manner by the ICV administration of the potent oxytocin antagonist d(CH2)5Tyr(Me)-Orn8-vasotocin. In contrast, the PVN injection of d(CH2)5Tyr(Me)-Orn8-vasotocin (1-30 ng), while effective in preventing oxytocin effect, was unable to prevent apomorphine response. On the other hand, apomorphine-, but not oxytocin-induced penile erection and yawning was prevented by electrolytic lesion of the medial septum (MS). Such a lesion decreased oxytocin content by about 45% in the hippocampus. The above results suggest that the hypothalamic-hippocampal oxytocinergic pathway mediates apomorphine-induced penile erection and yawning and that oxytocin is involved at different levels in the CNS for the control of these behavioral responses.

Animals↗
PubMed1992

Apomorphine- and oxytocin-induced penile erection and yawning in male rats: effect of pertussis toxin.

The effect of the intracerebroventricular (ICV) administration of pertussis toxin on penile erection and yawning induced by apomorphine and oxytocin was studied in male rats. Pertussis toxin (2 micrograms ICV) prevented the above behavioral responses to apomorphine (80 micrograms/kg SC) and oxytocin (30 ng ICV) on day 3 and 4, but not on day 0 and 1 after treatment. Oxytocin and apomorphine responses were restored on day 6. Similar results were obtained by microinjecting pertussis toxin (0.5 microgram) in the paraventricular nucleus of the hypothalamus, the most sensitive brain area for the induction of penile erection and yawning by oxytocin and apomorphine. The results suggest that G proteins are involved in the expression of above responses to apomorphine and oxytocin.

Animals↗
PubMed1992

Proteolytic conversion of neurohypophyseal peptides by rat thymocytes: involvement of endopeptidases.

The proteolytic conversion of oxytocin and Arg8-vasopressin by purified rat thymocytes was studied at 37 degrees C and physiological pH 7.4. The formed peptide fragments were isolated by high performance liquid chromatography and characterized by amino acid analysis. When oxytocin was incubated with rat thymocytes, oxytocin 1-8 and oxytocin 1-7 were isolated. In contrast, only Arg8-vasopressin 1-8 was found when Arg8-vasopressin was incubated with thymocytes. The formation of oxytocin 1-8, oxytocin 1-7 and Arg8-vasopressin 1-8 was prevented partially by 10(-3) M phenylmethylsulfonyl fluoride and iodoacetamide, and abolished by 0.5 x 10(-3) M Zn2+ and Hg2+ ions and 10(-3) M o-phenanthroline, but not by 10(-5) M leupeptin, lima bean trypsin inhibitor, trasylol, captopril and phosphoramidon. 0.5 x 10(-3) M EDTA was without effect on the formation of oxytocin 1-8 and Arg8-vasopressin 1-8 but increased by about 30% the formation of oxytocin 1-7. The results suggest that proteases capable of metabolizing oxytocin and Arg8-vasopressin are localized in the thymocyte surface membrane. Since oxytocin and vasopressin are synthetized by thymic epithelial cells and exert several actions on thymocytes, these proteases may play a physiological role in the inactivation of neurohypophyseal peptides at the thymocyte level.

Amino Acids↗