Prenatal kolanut exposure suppresses hippocampal dentate gyrus neurogenesis in adolescent and young adult rats

Abstract Kolanut, a social delicacy for men and women, including pregnant women, in West African countries, and in sub-Saharan African continent contains caffeine, theobromide and tannins. This study investigated the possible adverse effects of kolanut following prenatal exposure on hippocampal neurogenesis in adolescent rats. 12 Sprague Dawley pregnant rats were exposed to 400 mg/kg kolanut consumption daily from first day until parturition. 24 pups were grouped into three groups of 8 pups into postnatal day (PND) 21, 56 and 70, and each sub grouped into control and treated groups. Six brain sections per animal were processed for Nissl, DCX and Ki-67 immunohistochemical staining, malonaldehyde (MDA) and brain derived neurotropic factor (BDNF) using ELISA technique. Histomorphology examination on Nissl stain sections showed gestational significantly reducing mean area, mean diameter and mean neuronal density at PND 21 and 56 and significantly inhibited DCX immunoreaction and expression in migrating neurons in subgranular zone of dentate gyrus at PND 21, 56 and 70 in comparison to control groups respectively. At PND 21 and 70, gestational kolanut treatment suppressed cumulative neurogenesis by inhibiting expression of Ki-67 protein in subgranular zone of dentate gyrus but significantly increased hippocampal expression of BDNF protein at PND 56 and 70 and hippocampal MDA concentration at PND 21, 56 and 70. Prenatal gestational kolanut consumption adversely decreased the process of neurogenesis and inhibited normal neuronal maturation and differentiating processes and provoked decreased generation of neural progenitor cells in the hippocampus, suggesting caution/moderation in the use of kolanut by pregnant women to avert possible postnatal cognitive defects in their children later in life.