Paternal stress alters synaptic density and expression of GAP-43, GRIN1, M1 and SYP genes in the hippocampus and cortex of offspring of stress-induced male rats

•Paternal stress altered the immunoreactivity to synaptophysin in the prefrontal cortex and hippocampus of offspring.•Downregulation of genes involved in the process of learning and formation of memory such as GAP-43, GRIN1, M1 and SYP genes in offspring of stressed males.•Environmental enrichment after stress could reverse the stress-induced impacts. Adverse experiences during pregnancy have a negative impact on the neuronal structure and behavior of offspring, but the effects of a father's life events on the outcome of progeny are scarce. The present study is intended to investigate whether paternal stress affects the offspring brain structure, especially those regions concerned with learning and formation of memory, namely the hippocampus (HC) and prefrontal cortex (PFC), and also the expression of certain genes linked to learning and memory in the offspring. Induced stress to male rats by five stressors, one per day followed by allowing them to mate with the normal, unstressed female. Synaptophysin immunoreactivity was assessed in the tissue sections of the HC and PFC as well as expression of genes concerned with learning and memory was evaluated by RT-PCR in the progeny of stress-received males. The progeny of stressed rats had reduced antisynaptophysin immunoreactivity in the HC and PFC. The synaptic density in HC was less in the A-S (Offspring of male rats who received stress during adulthood) and PA-S (offspring of male rats who received stress during both adolescence and adulthood) than in P-S (offspring of male rats who received stress during adolescence) and C-C (offspring of control) groups. Similar results were observed even in the PFC. The results of post hoc tests proved that the HC and PFC of the progeny of stress-exposed rats exhibited considerably less synaptic density than control (P