Therefore,

increased maternal inhibitors norepinerphine may play a role in the PNS phenotype. This hypothesis is strengthened by the observations in the offspring of dams treated with propranolol, a beta-adrenoreceptor antagonist, showing up-regulation of fetal beta 1-adrenoceptors, and increases in norepinephrine activity in adulthood (Erdtsieck-Ernste et al., 1993). To what extent antagonism of the beta-adrenergic receptor also alters the behavioral phenotype of the offspring remains to be studied. Apart from direct effects on the offspring, sympathetic activation may affect the offspring’s phenotype by altering glucocorticoid transport across the placenta. A SRT1720 in vivo study in human cell culture suggests that heightened norepinephrine decreased expression of Hsd11b2 ( Sarkar et al., 2001). Another pathway through which maternal stress could impact the development of the offspring is altered immune system activity. In general, stress exposure leads to increased immune activation and subsequent higher levels of pro-inflammatory cytokines in the dams. In humans, immune activation during pregnancy, such as viral infection during pregnancy, has been associated with heightened risk for neuropsychiatric disorders like schizophrenia and autism (Brown and Derkits, 2010, Chess, 1977 and Wilkerson et al.,

2002). However, the immune response induced by infection may be different this website from the response induced by stress. A study in mice showed that increases in interleukin-6 and interleukin-8 during below pregnancy predicted higher maternal weight which is associated with an increased metabolic risk for the offspring, however, no significant correlations were found between maternal cytokine levels and fetal adiposity. This study did not assess if the maternal cytokine levels during pregnancy predict the metabolic phenotype of the offspring in adulthood (Farah et al., 2012). Overall, the

data on the effects of maternal immune activation due to stress on the offspring phenotype is limited. In future studies a thorough investigation of the cytokine levels in both dam and fetus may advance our knowledge on the underlying mechanisms. PNS has been shown to alter the development of the amygdala, prefrontal cortex and hippocampus (Coe et al., 2003, Fujioka et al., 2006, Kawamura et al., 2006 and Kraszpulski et al., 2006). In summary, prenatal stress was shown to decrease neurogenesis (Coe et al., 2003 and Fujioka et al., 2006), neuronal arborization (Kraszpulski et al., 2006),neuronal density (Kawamura et al., 2006) these brain areas. Furthermore, dendritic architecture was shown to be altered in PNS rats (Jia et al., 2010). Finally, PNS exposure resulted in decreased neuronal connectivity (Goelman et al., 2014). In addition to amygdala, prefrontal cortex and hippocampal development, it may be that exposure to prenatal stress induces changes in development of the hypothalamus.