Oxytocin increases the density of high affinity α2-adrenoceptors within the hypothalamus, the amygdala and the nucleus of the solitary tract in ovariectomized rats
Department of Molecular Medicine, Endocrine and Diabetes Unit, Karolinska Institutet/Karolinska Hospital, S-171 76 Stockholm, Sweden. Brain Research
(Impact Factor: 2.84).
08/2005; 1049(2):234-9. DOI: 10.1016/j.brainres.2005.05.034
Oxytocin induces long-term changes in, for example, blood pressure, spontaneous motor activity and corticosterone levels in rats. Previous studies in male rats have suggested a role for alpha(2)-adrenoceptors within the central nervous system in these effects. The aim of the present study was to investigate if oxytocin treatment in female rats would influence alpha(2)-adrenoceptors within the hypothalamus, the amygdala and the nucleus of the solitary tract (NTS). For this purpose, female ovariectomized (OVX) rats were treated with oxytocin (1 mg/kg s.c.) or saline once a day for 10 days. Rats were decapitated 5 days after the last injection, and brains and plasma were collected. Quantitative receptor autoradiography for characterization of high affinity alpha(2)-adrenoceptor agonist binding and radioimmunoassay for corticosterone were performed. Oxytocin increased the B(max) values of the alpha(2)-adrenoceptor agonist [3H]UK14.304 binding sites significantly in all the analyzed areas (P<0.05). K(d) values were unchanged. Plasma levels of corticosterone were significantly decreased in the oxytocin-treated rats (P<0.05). These findings are in further support of an interaction between oxytocin receptors and alpha(2)-adrenoceptors and show that oxytocin treatment may increase alpha(2)-adrenoceptor recognition probably leading to an increase in alpha(2)-adrenoceptor signaling in several parts of the brain.
Available from: Dasiel Oscar Borroto Escuela
- "Oxytocin can induce anti-stress-like effects such as reduction of blood pressure and cortisol levels. It increases pain thresholds, exerts an anxiolytic-like effect and stimulates various types of positive social interactions (Uvnas-Moberg and Petersson, 2005). It has been indicated as a " cuddle " transmitter. "
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ABSTRACT: This article is focused on understanding the mechanisms for the interactions between the central catecholamine (CA) and oxytocin (OXY) neurons and their relevance for brain function especially social behaviour in the field of pair bonding. Such a topic is analysed under two perspectives namely the intercellular communication modes between CA and OXT neurons and the molecular integrative mechanisms at the plasma membrane level between their respective decoding systems. As a matter of fact, recent observations strongly indicate a major role of volume transmission and receptor-receptor interactions in the CA/OXT neuron interplay in the brain control of social behaviour and pair bonding. This article is part of a Special Issue entitled: Brain Integration.
Available from: Linda Handlin
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ABSTRACT: The aim of the present thesis was to investigate hormonal and physiological effects in mothers during a breastfeeding session and in dogs and their owners in response to short-term interaction. In study one, sixty-six mothers receiving either exogenous oxytocin infusion and/or epidural analgesia (EDA) during labor or intramuscular oxytocin injection post partum were studied. Oxytocin, prolactin, adrenocorticotrophic hormone (ACTH) and cortisol levels, as well as blood pressure were measured during a breastfeeding session two days after birth. In response to breastfeeding two days after birth, the mothers displayed a pulsatile release of oxytocin and increasing prolactin levels. In addition, the activity in the HPA-axis was reduced and maternal blood pressure decreased. The results also show that EDA administration in combination with oxytocin during labor resulted in significantly lower oxytocin levels and higher cortisol levels, as well as higher blood pressure in response to breastfeeding two days after birth, compared to EDA administration alone. In addition, oxytocin infusions dose-dependently lowered the mothers’ endogenous oxytocin levels two days after birth. In study two, ten female dog owners and their male Labrador dogs participated, together with ten controls. Their levels of oxytocin, cortisol and insulin, as well as their heart rate, were measured. The connection between the quality of the dog-owner relationship and hormone levels was also explored. Short-term interaction between dogs and their owners resulted in oxytocin release in both species and their cortisol levels and heart rate were also affected. Oxytocin levels and positive attitudes regarding the dog-owner relationship were positively correlated. In conclusion, both human-human and human-animal interactions induce oxytocin release and promote oxytocin mediated effects, such as decreasing cortisol levels and blood pressure. In addition, social interaction and oxytocin levels are positively related.
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ABSTRACT: Stress may lead animal and human behavior to an unstable condition in short and long term. It is a risk factor to a mental disorder such as depression, which is generally related to a failure after an effort. Its high prevalence is worldwide and it is a WHO (World Health Organization) concern. Depression may impair social, economical and affective relationships, besides bringing great suffering to the human being. The main symptoms are decreased energy and motivation, anhedonia, sadness, difficulty for concentration and memory, bonding disruptions, etc. The most accepted hypothesis for depression can be well recognized by the main drugs currently adopted for its treatment: they include serotonin and noradrenaline as their fundamental basis. However, their efficacies are still limited. A promising candidate that might help modulate this disease is oxytocin (OT). OT is a nonapeptide produced by the hypothalamus which exerts central and peripheral effects, not only during pregnancy and lactation, but acts in male and non pregnant females as well. It is being considered as an antistress neuropeptide and it has antidepressive effects. However, the blood brain barrier greatly impairs peripheral OT to reach the brain. The general goal of this review is to raise some issues concerning advantages and difficulties related to a possible exogenous administration of OT for this mental disorder. More specifically, it will be reviewed: 1. stimuli for OT release (behavioral/endocrinological and chemical/drugs); 2. OT effects on the central nervous system, mainly related to stress; 3. exogenous OT: routes of administration, blood brain barrier, indirect mechanisms of action, whole molecule x fragments of OT, doses. This review will not cover all aspects of the multifactorial disorder such as depression into all its variables. However, it may contribute to the understanding of one possible component, the oxytocinergic system.
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