The Prenatal Hypoxic Pathology Associated with Maternal Stress Predisposes to Dysregulated Expression of the <i>chrna7</i> Gene and the Subsequent Development of Nicotine Addiction in Adult Offspring

Abstract

<b><i>Introduction:</i></b> Previous studies have shown that fetal hypoxia predisposes individuals to develop addictive disorders in adulthood. However, the specific impact of maternal stress, mediated through glucocorticoids and often coexisting with fetal hypoxia, is not yet fully comprehended. <b><i>Methods:</i></b> To delineate the potential effects of these pathological factors, we designed models of prenatal severe hypoxia (PSH) in conjunction with maternal stress and prenatal intrauterine ischemia (PII). We assessed the suitability of these models for our research objectives by measuring HIF1α levels and evaluating the glucocorticoid neuroendocrine system. To ascertain nicotine dependence, we employed the conditioned place aversion test and the startle response test. To identify the key factor implicated in nicotine addiction associated with PSH, we employed techniques such as Western blot, immunohistochemistry, and correlational analysis between <i>chrna7</i> and <i>nr3c1</i> genes across different brain structures. <b><i>Results:</i></b> In adult rats exposed to PSH and PII, we observed increased levels of HIF1α in the hippocampus (HPC). However, the PSH group alone exhibited reduced glucocorticoid receptor levels and disturbed circadian glucocorticoid rhythms. Additionally, they displayed signs of nicotine addiction in the conditioned place aversion and startle response tests. We also observed elevated levels of phosphorylated DARPP-32 protein in the nucleus accumbens (NAc) indicated compromised glutamatergic efferent signaling. Furthermore, there was reduced expression of α7 nAChR, which modulates glutamate release, in the medial prefrontal cortex (PFC) and HPC. Correlation analysis revealed strong associations between <i>chrna7</i> and <i>nr3c1</i> expression in both brain structures. <b><i>Conclusion:</i></b> Perturbations in the glucocorticoid neuroendocrine system and glucocorticoid-dependent gene expression of <i>chrna7</i> associated with maternal stress response to hypoxia in prenatal period favor the development of nicotine addiction in adulthood.