| Popis: |
In the female rat, oxytocin (OT) is recognized for its role in regulating reproductive functions, both as a hormone in the general circulation and as a neurotransmitter in the central nervous system (CNS). As a hormone, OT produces contractions of the pregnant uterus and mammary gland. Its neurotransmitter actions range from the modulation of neuroendocrine reflexes (milk-ejection reflex) to the establishment of complex social and bonding behaviours related to reproduction and care of the offspring. This diversity of effects has led to OT being considered as a coordinating factor, ensuring that the behavioural, physiological and neuroendocrine changes appropriate to lactation are activated at the correct time in the peri-partum period [1,2]. In this respect, expression of OT receptors in some areas of the CNS is modulated by levels of gonadal steroids in the circulation and the sequence of changes of these levels, especially towards the end of gestation. However, some OT receptors are insensitive to changing steroid levels, allowing for differential activation of OT-dependent pathways. The studies reported here concern the pharmacological characterisation of OT receptors in different areas of the CNS (especially in areas displaying contrasting steroid sensitivity); the demonstration that the electrophysiological effect of activation of OT receptors in the limbic system may change during the peripartum period; and the proposal that one of the central actions of OT may be to reduce anxiety levels in the lactating rat. |
