Hypothalamic Vasopressin Gene Expression Increases in Both Males and Females Postpartum in a Biparental Rodent

Abstract

In previous studies, the closely related neuropeptide hormones oxytocin and vasopressin have been implicated in the central mediation of parental behaviour. Several studies in rats and sheep have demonstrated a role for oxytocin in the initiation of maternal behaviour. Recently, a few studies in a biparental species, the prairie vole (Microxytocinus ochrogaster) have suggested that vasopressin is important for paternal care. The present study investigated this latter possibility by measuring changes in vasopressin and oxytocin hypothalamic gene expression 1 day and 6 days following parturition in prairie voles which show paternal care and in montane voles (M. montanus) which lack paternal care. In prairie voles, vasopressin gene expression increased in both males and females postpartum, relative to sexually naive controls. In the non-paternal montane vole, no change in vasopressin gene expression was observed in either sex. In contrast to this species difference in vasopressin gene expression, hypothalamic oxytocin gene expression increased in both prairie and montane vole females, but not in males of either species. To augment measures of gene expression, we assessed vasopressin (V1a) and oxytocin receptor binding in both species. Although forebrain vasopressin V1a receptor binding was not altered following parturition in either species, oxytocin receptor binding increased in the ventromedial nucleus of the hypothalamus in females, but not males, in both prairie and montane voles. In summary, vasopressin gene expression increases in both males and females postpartum in a biparental species and oxytocin gene expression and receptor binding increase selectively in females. These results are consistent with earlier reports of a role for vasopressin in paternal care and for oxytocin in maternal behaviour.

Progesterone receptors mediate male aggression toward infants

“…PR activation may sustain or suppress activity in neurotransmitter circuitries that have been implicated in parental behaviors, such as those that produce vasopressin (2,25,26) and oxytocin (27). Activated PR may also modulate signaling through other steroid receptor-mediated signaling pathways, such as those mediated by estrogen receptors (ERs) (28,29).…”

Arginine vasopressin V1a receptor antagonist impairs maternal memory in rats

“…Exogenous AVP is capable of inducing maternal behavior in rats [16], and the infusion of a V1 antagonist into the medial preoptic area suppresses the behavior [17]. Additionally, AVP stimulates paternal behavior in prairie voles [18] and meadow voles [19], and central vasopressin gene expression is elevated in both sexes in biparental prairie voles [20]. However, more work is needed to clarify the role of AVP during this reproductive state, as little is known about its possible role in maternal memory.…”

Examination of AVPR1a as an autism susceptibility gene

“…3,4 One biomolecular pathway that clearly influences social behavior, and is therefore worthy of consideration in autism, is the argininevasopressin (AVP) system. The hormone AVP has been shown, across numerous organisms, to influence such varied social traits as vocal modulation, 5 sexual and parenting behavior, 6 mate affiliation and attachment, 7 aggression, 8 and social recognition. 9 The effects of AVP tend to be more pronounced in males, as opposed to the related hormone, oxytocin, whose effects tend to be stronger in females.…”