The influence of forepaw palmar sensorimotor deprivation on learning and memory in young rats

This study examined the effects of early palmar forepaw sensorimotor deprivation on learning and memory in rats. Sensorimotor deprivation was performed on 18-day-old male rats. Controls were sham operated. Studies were performed on rats aged 18, 25, 35, 45 and 60 days. Morris water maze testing was used to assess learning and memory. Long-term potentiation (LTP) was assessed by electrophysiological means in slices obtained from the hippocampal Schaffer collateral pathway. Nissl staining was performed to assess pyramidal cell number in hippocampal CA1 and CA3 regions. Hippocampal N-methyl-d-aspartate receptor 1 (NMDAR1) mRNA and protein levels were assessed. Learning and short-term memory were significantly depressed in 25 and 35 day old sensorimotor deprived rats (P<0.01). LTP was also significantly depressed in sensorimotor deprived rats at these ages, while hippocampal CA1 pyramidal cell counts were significantly decreased (P<0.05). CA3 cell numbers were significantly lower in 25-day-old sensorimotor deprived rats (P<0.05). Both NMDAR1 mRNA and protein levels were significantly lower in sensorimotor deprived rats aged 25 and 35 days (P<0.05). These findings indicate that palmar surface forepaw sensorimotor deprivation impairs subsequent learning and memory in young rats. Decreased hippocampal pyramidal cell numbers and altered NMDAR1 expression may underlie this impairment.