Sexually Dimorphic Brain Regions
Prenatal stress does have an effect on brain sexual differentiation after measuring the volume of the sexually dimorphic nucleus of the preoptic area of both female and males in the control and stressed groups. Prenatal stress inhibits the masculinzation of the male brain by inhibiting the growth of the sexually dimorphic nucleus of the preoptic area. Previous studies found that a decrease in testosterone is seen in pups of prenatally stressed mothers. Authors suggest this may cause the reduced in the sexually dimorphic nucleus of the preoptic area and says it is similar to the effects of neonatal castration. Also, stressed males had larger sexually dimorphic nucleus of the preoptic area at birth, but then at 20 and 60 days are found to only have 50% of the volume of the control males. Whereas control males are two times larger than control females on days 20 and 60, but the stressed males show no statistical difference to control females on respective days. These findings show support that the male brain is not showing the expected sexual dimorphism when prenatally stressed. Another study led by Kerchner et al. investigated the volume of the medial amygdala and the two compartments posterodorsal and the posteroventral in mice that also were prenatally stressed. Posterodorsal is thought to show organizational and activational effects from gonadal steroids. The medial amygdala for the control and stressed males was 85% larger than females with the males (stressed and control) resembling each other. To look for specific regions within the medial amygdala that may have been affected, data showed that both the posterodorsal and posteroventral, all male groups were larger in volume than the females, but male groups did not significantly differ from each other. This study confirmed that the medial amygdala is sexually dimorphic; the males are larger than the females. The posterodorsal and posteroventral were shown to be sexually dimorphic too. The writer suggested that these areas may act similarly to sexually dimorphic nucleus of the preoptic area in response to testosterone, but prenatal stress did not show an effect on the medial amygdala as it does on the sexually dimorphic nucleus of the preoptic area. Also, the posteroventral was 40% larger in control males than females. These results were thought to be caused by the sensitive period of the medial amygdala which is in the first days after birth. The medial amygdala, posterodorsal and posteroventral all show to be resistant against demasculinization from prenatal stress.
Read more about this topic: Prenatal Stress
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