Oxytocin promotes bone formation during the alveolar healing process in old acyclic female rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Idazoxan and the effect of intracerebroventricular oxytocin or vasopressin on sodium intake of sodium-depleted rats

The alpha(2)-adrenergic agonist clonidine and the neuropeptide oxytocin, inhibit sodium intake when injected intracerebroventricularly (i.c.v.). The present work investigates whether (1) vasopressin also inhibits sodium intake when injected i.c.v., and (2) the effect of oxytocin and of vasopressin on sodium intake is affected by i.c.v. injection of idazoxan, an alpha(2)-adrenergic antagonist. Clonidine (30 nmol), oxytocin (40, 80 nmol) and vasopressin (40, 80 nmol) were injected i.c.v. 20 min prior to a 1.5% NaCl appetite test, in rats depleted of sodium for 24 h by a combination of a single s.c. injection of furosemide (10 mg/rat) and removal of ambient sodium. Every dose of clonidine, oxytocin and vasopressin inhibited the 1.5% NaCl intake. Seizures were observed with the higher dose of vasopressin, but not with either dose of oxytocin. The effect of i.c.v. injection of clonidine (30 nmol), oxytocin (80 nmol) or vasopressin (40 nmol) was partially inhibited by prior i.c.v. injection of idazoxan (160, 320 nmol). The results suggest that the inhibition of 1.5% NaCl intake induced by i.c.v. injection of neuropeptides in sodium-depleted rats depends, in part, on the activation of central alpha(2)-adrenoceptors. (C) 1997 Elsevier B.V. B.V. All rights reserved.

Effect of oxytocin on transepithelial transport of water and Na+ in distinct ventral regions of frog skin (Rana catesbeiana)

Thoracic, abdominal, and pelvic fragments of ventral skin of Rana catesbeiana were analysed regarding the effect of oxytocin on: (1) transepithelial water transport; (2) short-circuit current, (3) skin conductance and electrical potential difference; (4) Na+ conductance, the electromotive force of the Nat transport mechanism, and shunt conductance; (5) short-circuit current responses to fast Na+ by K+ replacement in the outer compartment, and (6) epithelial microstructure. Unstimulated water and Na+ permeabilities were low along the ventral skin. Hydrosmotic and natriferic responses to oxytocin increased from thorax to pelvis, Unstimulated Na+ conductance was greater in pelvis than in abdomen, the other electrical parameters being essentially similar in both skin fragments. Contribution of shunt conductance to total skin conductance was higher in abdominal than in pelvic skin. Oxytocin-induced increases of total skin conductance, Na+ conductance, and shunt conductance in pelvis were significantly larger than in abdomen, An oscillatory behaviour of the short-circuit current was observed only in oxytocin-treated pelvic skins. Decrease of epithelial thickness and increase of mitochondria-rich cell number were observed from thorax to pelvis, Oxytocin-induced increases of interspaces were more conspicuous in pelvis and abdomen than in thorax.

Progesterone (PR), Oestrogen (ER-alpha and ER-beta) and Oxytocin (OTR) Gene Expression in the Oviduct and Uterus of Pregnant and Non-pregnant Bitches

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

13,14-Dihydro-15-Keto Prostaglandin F-2 alpha Release in Response to Oxytocin Challenge Early Post-Partum in Anoestrous Nelore Cows Submitted to Temporary Calf Removal and Progesterone Priming

The study evaluated, in early post-partum anoestrous Nelore cows, if the increase in plasma oestradiol (E2) concentrations in the pre-ovulatory period and/or progesterone priming (P4 priming) preceding ovulation, induced by hormonal treatment, reduces the endogenous release of prostaglandin PGF(2)alpha and prevents premature lysis of the corpus luteum (CL). Nelore cows were subjected to temporary calf removal for 48 h and divided into two groups: GPE/eCG group (n = 10) and GPG/eCG group (n = 10). Animals of the GPE/eCG group were treated with a GnRH agonist. Seven days later, they received 400 ID of eCG, immediately after PGF(2)alpha treatment, and on day 0, 1.0 mg of oestradiol benzoate (EB). Cows of the GPG/eCG group were similarly treated as those of the GPE/eCG group, except that EB was replaced with a second dose of GnRH. All animals were challenged with oxytocin (OT) 9, 12, 15 and 18 days after EB or GnRH administration and blood samples were collected before and 30 min after OT. Irrespective of the treatments, a decline in P4 concentration on day 18 was observed for cows without P4 priming. However, animals exposed to P4 priming, treated with EB maintained high P4 concentrations (8.8 +/- 1.2 ng/ml), whereas there was a decline in P4 on day 18 (2.1 +/- 1.0 ng/ml) for cows that received GnRH to induce ovulation (p < 0.01). Production of 13,14-dihydro-15-keto prostaglandin F-2 alpha (PGFM) in response to OT increased between days 9 and 18 (p < 0.01), and this increase tended to be more evident in animals not exposed to P4 priming (p < 0.06). In conclusion, the increase in E2 during the pre-ovulatory period was not effective in inhibiting PGFM release, which was lower in P4-primed than in non-primed animals. Treatment with EB promoted the maintenance of elevated P4 concentrations 18 days after ovulation in P4-primed animals, indicating a possible beneficial effect of hormone protocols containing EB in animals with P4 priming.

Ionotropic Glutamate Receptors in Hypothalamic Paraventricular and Supraoptic Nuclei Mediate Vasopressin and Oxytocin Release in Unanesthetized Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Polymorphisms in Oxytocin and alpha(1a) Adrenergic Receptor Genes and Their Effects on Production Traits in Dairy Buffaloes

The use of molecular markers may auxiliary the buffalo breeding. The oxytocin (OXT) and the adrenergic receptor alpha(1A) (ADRA1A) may be involved in milk ejection in ruminants. The aim of this study was to verify the existence of polymorphisms in the OXT and ADRA1A genes and their associations with milk production traits. A total of 220 buffaloes were genotyped using PCR-RFLP for both genes. The SNP identified in the ADRA1A gene was associated with protein percentage in dairy buffaloes. This is the first report of such association in the literature, which has not been studied in other species.

Intervenções benéficas durante o parto para a prevenção da mortalidade materna

O caráter multifatorial das complicações e da mortalidade materna torna difícil e demorada a tarefa de seu controle a longo prazo. A atenção profissional à mulher gestante e/ou parturiente representa seguramente elemento chave para a obtenção de bons resultados, tanto maternos quanto perinatais. Partindo-se do pressuposto de que atenção médica profissional ao parto de maneira adequada tem a capacidade de diminuir a ocorrência de complicações associadas à morbidade e mortalidade materna, são apresentadas resumidamente as evidências sobre algumas intervenções incluídas nesta atenção. São enfocadas as evidências derivadas de estudos realizados com extremo rigor metodológico e científico, os ensaios controlados randomizados, sobre intervenções capazes de reduzir as complicações e a mortalidade materna. Estas principais intervenções referem-se basicamente a: atenção institucional ao parto, atendimento profissional capacitado, utilização de parteiras tradicionais em determinados contextos, uso de tecnologias apropriadas incluindo o partograma, local do parto, posição para o parto, uso de episiotomia, tipo de parto, uso de ocitócicos na fase ativa do parto, realização de esforços de puxo no período expulsivo, manejo da dequitação e profilaxia da hemorragia puerperal. Ainda que o efeito de prevenir mortes seja difícil de ser avaliado pela baixa freqüência, sua utilização de forma racional e padronizada, por meio de manuais e normatizações de condutas de serviços, tem um efeito positivo sobre a qualidade da atenção ao nascimento. Isso faz parte do contexto técnico e humano do direito que toda mulher tem ao melhor atendimento possível nesse momento tão especial de sua vida.

Elevated progesterone concentrations enhance prostaglandin F-2 alpha synthesis in dairy cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prolonged interval between parturition of normal live pups in a bitch

On day 64 after artificial insemination, a six-year-old primiparous briard bitch whelped three live pups between 05.00 and 08.00. It was presented at 11.00 on the same day with failure to complete parturition. on ultrasound examination, a normal live fetus was observed and the bitch was treated with oxytocin three times during the day (1(.)0, 2(.)0 and 2(.)0 iu intramuscularly), with no effect. The following day, a higher dose of oxytocin (5(.)0 iu) was administered intramuscularly at 11.00, after a uterine ultrasound examination confirmed viability of the fetus. At 18.00 of the same day, the bitch whelped the fourth normal live pup, 37 hours after initiation of parturition and 34 hours after expulsion of the last fetus. Effectiveness of oxytocin and normal versus prolonged parturition due to uterine inertia are discussed.

Water deprivation and the double- depletion hypothesis: common neural mechanisms underlie thirst and salt appetite

Water deprivation-induced thirst is explained by the double-depletion hypothesis, which predicts that dehydration of the two major body fluid compartments, the extracellular and intracellular compartments, activates signals that combine centrally to induce water intake. However, sodium appetite is also elicited by water deprivation. In this brief review, we stress the importance of the water-depletion and partial extracellular fluid-repletion protocol which permits the distinction between sodium appetite and thirst. Consistent enhancement or a de novo production of sodium intake induced by deactivation of inhibitory nuclei (e.g., lateral parabrachial nucleus) or hormones (oxytocin, atrial natriuretic peptide), in water-deprived, extracellular-dehydrated or, contrary to tradition, intracellular-dehydrated rats, suggests that sodium appetite and thirst share more mechanisms than previously thought. Water deprivation has physiological and health effects in humans that might be related to the salt craving shown by our species.

Role of serotonergic 5-HT1A and oxytocinergic receptors of the lateral septal area in sodium intake regulation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)