| Prenatal opioids exposure negatively affects the neurobehavioral abilities of children born from dependence
dams. Adolescent housing conditions can buffer the detrimental impacts of early life experiences or contradictory
can worsen individual psychosocial functions. The present study investigated the effects of maternal morphine
dependence and different rearing conditions on behaviors and protein expression in brain reward circuits of male
pups. Female Wistar rats a week before conception, during pregnancy and lactation were injected twice daily
with escalating doses of morphine or saline. On a postnatal day 21, male pups were weaned and subjected to
three different environments for two months: standard (STD), isolated (ISO), or enriched environment (EE). The
anxiety and drug-related reward were measured using elevated plus maze, open field test, and conditioned place
preference. Western blotting was used to determine the protein level of ΔFosB and μ-opioid receptor proteins in
the striatum and the midbrain of male offspring, respectively. Results showed that maternal morphine administration dramatically increased anxiety-like and morphine place preference behaviors in offspring. Also, ISO
condition aggravated these behavioral outcomes. While, rearing in EE could attenuate anxiety and morphine
conditioning in pups. At molecular levels, maternal morphine exposure and social isolation markedly increased
both of ΔFosB and μ-opioid receptor proteins expression. However, rearing in the EE declined ΔFosB protein
expression. Together, these findings help to elucidate long lasting impacts of early life morphine exposure and
rearing environment on the behavioral and molecular profile of addicted individuals. |