Oral THC produces minimal behavioral alterations in preadolescent rats

Although the oral route has traditionally been used for THC administration during the perinatal period in the rat, most studies administering THC during the postnatal period utilize intraperitoneal (ip) administration. In an effort to utilize the same route of administration in both prenatal and postnatal studies, we administered Δ-9-tetrahydrocannabinol (THC) in sesame oil by gavage during postnatal days 22–40 (equivalent to childhood to early adolescence) to male and female rats. We quantified behavior 40 min after administration in the Accuscan activity monitor on days 22, 29 and 40. In addition, we examined active and passive avoidance behaviors in treated adults. Acutely, THC had subtle effects on activity when measured during the period of drug administration and minimal effects on avoidance behaviors examined up to 140 days of age.Since several groups have found that lower doses of THC administered intraperitoneally to periadolescent rats do produce behavioral alterations, we suspect that the inordinately slow absorption of the drug via the oral route may be responsible for the paucity of significant findings in our study. Therefore, oral administration of THC, particularly under conditions of mild food deprivation, may lead to sub-psychoactive concentrations of the drug within the brain.