Early Prenatal Stress Increases Body Weight and Reduces Nociception in Adult Male Rats
A.O. Afolabi
Department of Physiology, College of Health Sciences, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo, Nigeria.
I. A. Alagbonsi *
Department of Physiology, Faculty of Medicine, Kogi State University, P.M.B. 1008, Anyigba, Kogi, Nigeria.
O. D. Oke
Department of Physiology, College of Health Sciences, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: Behavioral responses of 3-month-old male pups from female Wistar rats exposed to daily 1 hour or 3 hour restraint stress during the first 7 days of pregnancy were studied by tail flick and formalin test.
Methodology: Eighteen mature virgin female albino rats (140g-160g) were randomly allocated in a blinded fashion to 3 groups (n=6 each) and mated. Group 1 rats were the control and did not undergo restraint stress. Groups 2 and 3 rats were restrained for 1 hour and 3 hours respectively during the first 7 days of pregnancy. Six male rats only served purpose of copulation. At 3 month of age, 34 pups consisting of 10, 11 and 13 pups delivered by rats in groups 1, 2 and 3 respectively were randomly selected and studied for nociception.
Results: Body weights were higher in both 1 hour and 3 hour prenatally stressed pups compared to that of the control. The latency period during the tail immersion test in the pups prenatally stressed for 3 hour daily but not those stressed for 1 hour daily was significantly higher (p<0.05) compared to that of control. While there were no significant differences in the formalin score in pups prenatally stressed for 1 hour and 3 hour compared to the score of the control during the early phase, the formalin score of the pups prenatally stressed for 3 hour daily but not those stressed for 1 hour daily was significantly lower compared to that of the control during the late phase.
Conclusion: Our findings suggest that early prolonged prenatal stress modulates nociceptive sensitivity in 3-month-old rat and that different mechanisms are responsible for the effects of prenatal stress on acute and persistent pain in the formalin test.
Keywords: Body weight, pain, prenatal stress, Rat