Transgenerational consequences of adolescent morphine exposure in female rats: effects on anxiety-like behaviors and morphine sensitization in adult offspring.
OBJECTIVE
Opiate abuse in adolescent girls has increased in the past decade; however, few animal studies have examined the potential consequences of opiate use occurring at this time. The purpose of the present study was to determine whether exposing female rats to morphine during the peripubertal period can alter the adult behavior of their offspring.


METHODS
Beginning at 30 days of age, female rats were injected subcutaneously (s.c.) twice daily with either morphine sulfate or saline. The initial morphine dose of 2.5 mg/kg was increased by 2.5 mg/kg daily for a total of 20 days. Ten days after the final drug treatment, all subjects were mated. Their subsequent offspring were then tested as adults on the elevated plus maze, in a novel environment or were examined in a morphine locomotor sensitization paradigm.


RESULTS
Adult female offspring of dams exposed to morphine during puberty spent less time in the open arms of the elevated plus maze and displayed decreased exploration in a novel environment. Female offspring also demonstrated a more rapid induction of morphine sensitization. Finally, male offspring demonstrated a significant enhancement in the expression of morphine sensitization.


CONCLUSIONS
Chronic morphine exposure during adolescence can have significant transgenerational effects on adult offspring. Future studies will be needed to determine how these changes are transferred to the offspring and whether these effects are specific to drug exposure that occurs during the peripubertal period.
Byrnes
Elizabeth M
EM
Department of Biomedical Sciences, Tufts University, Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA. elizabeth.byrnes@tufts.edu
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000209:etiology* / Q000523:psychology; D001522:Behavior, Animal / Q000187:drug effects*; D004334:Drug Administration Schedule; D004361:Drug Tolerance / Q000502:physiology; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D008124:Locomotion / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D009020:Morphine / Q000008:administration & dosage*; D009021:Morphine Dependence / Q000503:physiopathology*; D009294:Narcotics / Q000008:administration & dosage*; D049590:Postpartum Period / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D012726:Sexual Behavior, Animal / Q000187:drug effects; D013997:Time Factors
D009294:Narcotics; D009020:Morphine