Differential vulnerability of male versus female rats to long-term effects of birth insult on brain catecholamine levels

There are gender differences in the prevalence and severity of several human behavioral disorders, in which both obstetric complications and dysregulation of brain monoamine systems have been implicated. In animal studies, males are more susceptible than are females to lasting behavioral deficits following various perinatal insults. The current study compared monoamine levels in brain regions from adult male and female rats that had been born under various conditions-vaginal birth (control), Caesarean section (C-section), or C-section with 15 min of added anoxia (Anoxia). At adulthood, male rats born by C-section had increased dopamine (DA) levels in the nucleus accumbens and dorsal striatum, and decreased amygdalar norepinephrine (NE), compared to vaginally born males. C-sectioned female rats had increased NE levels in the thalamus in comparison to vaginally born females. The only monoamine change observed in the Anoxia groups was a decrease in nucleus accumbens NE in females. Thus addition of 15 min of anoxia to the C-section procedure reversed several of the monoamine changes produced by C-section alone. Birth group had no effect on serotonin in several brain regions in either sex. Male, but not female, rats born by C-section had decreased plasma epinephrine levels at birth and slightly increased brain lactate at 5 h after birth. Pups of both sexes in the Anoxia groups had high levels of plasma catecholamines at birth. The possible functional significance of the lasting, region-specific changes in brain DA and NE due to birth insult and possible roles of hormones at birth in producing these monoamine changes in the two sexes are discussed.