Evaluation of the effects of morphine consumption during lactation period on learning and memory of rat’s offspring

Background and Aim: The frequent use of opioids changes function and plasticity of neural circuits. Exposing the immature nervous system to opioids can have deeper and more extensive impacts. The aim of this study was to investigate the effects of morphine consumption during lactation period on learning and memory of rats offspring. Material and Methods: This experimental study included 40 male Wistar rats with age range of 45-50 days.&nbsp; Animals were divided into control group (CO) and 3 experimental groups of rats whose mothers had received subcutaneous injections of 5 (M5), 10 (M10) or 20 (M20) mg/kg morphine every 12 hours during lactation period. Spatial learning was evaluated by Morris water maze (MWM) on 4 consecutive days (4 trials/day). Spatial memory retrieval was also evaluated on the last day. &nbsp;&nbsp; Results: Our results indicated that the rats whose mothers had received morphine during lactation period spent more time and traveled more distance to find the hidden platform than the controls in the learning stage. These differences were statistically significant when doses of 10 and 20 mg/kg morphine (P<0.001) were used. Also, they spent less time and passed less distance in the target quadrant in probe trial (P<0.001). Conclusion: Morphine consumption during lactation period impairs spatial learning and memory of the rats' offspring in a dose dependent manner. Keywords: Morphine, Lactation period, Spatial learning, Memory, Rat. &nbsp; Received: Jan 16, 2018&nbsp;&nbsp;&nbsp;&nbsp; Accepted: May 22, 2018