The improving effect of melatonin on some anatomical parameters and functional memory outcomes of rats exposed to acetaminophen via modified T-Maze test

Abstract

The aim of this study is investigating the effect of melatonin on some anatomical parameters and the functional memory outcomes on rats (as an animal model) with autistic like behavior after administration with acetaminophen by modified T-maze spontaneous alternation test to examine the behavioral alteration(spatial learning and working). Thirty healthy Albino male rat pups were selected for this study. At post natal day 3 (PND3), rat pups were divided into three groups (10pups\group). Group 1were served as a control and includes pups which were injected subcutaneously with normal saline for 8 days then gavaged with normal saline for 2 weeks, Group 2 includes pups which were injected subcutaneously with (50 mg/kg) of acetaminophen once daily for 8 days then these pups were gavaged with normal saline for 2 weeks. Group 3 includes pups which were injected subcutaneously with (50 mg/kg) acetaminophen once daily for 8 days then gavaged with melatonin (10 mg/kg) for 2 weeks. Developmental parameters were monitored. Modified T-maze were performed test at PND22, 23, and 24 to determine the rat learning/memory deficits in all pups to compare between them.The present study demonstrated that acetaminophen exposed rat pups exhibited a significantly decrease in body weight of pups of acetaminophen groups(36.24±0.97)g in comparison with control, and melatonin groups (44.98±0.87),and (46.97±2.16) g respectively. A significant delay in the eye opening in pups of acetaminophen group (16.60±0.54) day when compared to that control (15.16±0.75) day and melatonin groups(15.50±0.53) day. Spontaneous alternation in T-Maze test suggested that the alternation rate from three consecutive days(PNDs 22,23,24) in the acetaminophen group (45.83±15.95 %) was significantly lowest when it was compared to the control (91.66± 9.62%) and melatonin groups(91.66± 16.67%),and also it demonstrate that pups of acetaminophen group have higher percentage of side-preference rate in comparison to that of the control and melatonin group.Acetaminophen induces several alteration in rat pups at dose 50 mg/kg/day from PND 3 to PND11.These alteration include the body weight, eye openinǵs day, functional memory outcomes. These alteration were ameliorated by administration with melatonin (10 mg/kg for 2 weeks) after exposure to acetaminophen.