Fatemeh Aghighi - Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
Mojgan Mohammadifar - Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
Hamidreza Banafshe - Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
Mahmoud Salami - Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran

Objective(s): In addition to genetic factors, environmental phenomena during postnatal age highly affect development and, in turn, function of the brain. The present work evaluates if morphine consumption during lactation period influences the spatial performances and synaptic plasticity in rats at neonatal period of age. Materials and Methods: Three groups of mothers were subcutaneously administered by 5 (M5), 10 (M10) or 20 (M20) mg/kg morphine every 12 hours during the lactation period. At 45 days old, their offspring were introduced to Morris water maze for assessment of spatial learning and memory. Basic field excitatory post-synaptic potentials (fEPSPs) were recorded in the CA1 area of hippocampus and, then, long term potentiation (LTP) was induced by tetanic stimulation. Results: We found that the M10 and M20 rats spent more time and traveled longer distance to find the hidden platform of maze when compared to the control animals (PConclusion: The present study provides behavioral and electrophysiological proofs for negative effect of morphine on the hippocampal-related function in the neonatally morphine-exposed rats.

Hippocampus, Lactation, Maze learning, Morphine, Rats, Spatial Memory, Synaptic plasticity