80 Nicotine increases eclampsia-like seizure threshold and attenuates microglial activity in rat hippocampus through the A7 nicotinic acetylcholine receptor

Abstract

Introduction A considerable number of studies have demonstrated that nicotine, a α 7-nicotinic acetylcholine receptor ( α 7-nAChR) agonist, can dampen immune response through the cholinergic anti-inflammatory pathway. Evidence suggests that inflammation plays a critical role in eclampsia, which contributes to maternal and fetal morbidity and mortality. Objectives In the present study, possible anti-inflammation and neuro-protective effects of nicotine via α 7-nAChRs have been investigated after inducing eclampsia-like seizures in rats. Methods Rat eclampsia-like models were established by administering lipopolysaccharide (LPS) plus pentylenetetrazol (PTZ) in pregnant rats. Rats were given nicotine from gestation day (GD) 14–19. Then, clinical symptoms were detected. Seizure severity was recorded by behavioral tests, serum levels of inflammatory cytokines were measured by Luminex assays, microglia and astrocyte expressions were detected by immunofluorescence, and changes in neuronal number in the hippocampal CA1 region among different groups were detected by Nissl staining. Results Our results revealed that nicotine effectively improved fetal outcomes. Furthermore, it significantly decreased systolic blood pressure, and maternal serum levels of Th1 cytokines (TNF- α , IL-1 β , IL-6 and IL-12P70) and an IL-17 cytokine (IL-17A), dramatically increased Th1 cytokine (IL-4) and eclampsia-like seizure threshold. Moreover, this attenuated neuronal loss and decreased the expression of microglial activation markers of the hippocampal CA1 region in the eclampsia-like group. Additionally, pretreatment with α -bungarotoxin, a selective α 7-nAChR antagonist could prevent the protective effects of nicotine in eclampsia-like model rats. Conclusion Our findings indicate that the administration of nicotine may increase eclampsia-like seizure threshold and attenuate microglial activity in rat hippocampus through the α 7 nicotinic receptor.