The ontogeny and the adult expression of motor behaviors were studied in male and female rats born from mothers exposed to delta 9-tetrahydrocannabinol (THC, 5 mg/kg) during gestation and lactation. Perinatal exposure to THC increased both rearing and locomotor activities in males and females at immature preweanling ages (P-15 and P-20). These effects disappeared after ceasing THC exposure (postweaning ages), but they were observed again in adult (P-70) females. The effects appeared as persistently high motor activity in familiar environments, disappearing the characteristic habituation profile in locomotor and exploratory behaviors. In novel environment condition tests, adult (P-70) THC-exposed females, but not males, exhibited lower locomotor activity in the socio-sexual approach test, and an increase in the emergence latency in the dark-light emergence test. Additionally, animals of both sexes exposed to THC showed a increase in the time spent grooming measured in novelty conditions. These findings suggest that perinatal exposure to THC affects both the development and the adult expression of motor behaviors and it resulted in a sex-dimorphic psychomotor activation very similar to that observed after perinatal exposure to other drugs of abuse. A possible role of THC-induced pituitary-adrenal (PA) axis activation was also evaluated by measuring plasma corticosterone levels in adult animals perinatally exposed: THC-exposed females exhibit a clear increase of this adrenal hormone, whereas THC-exposed males displayed lower levels of this hormone.(ABSTRACT TRUNCATED AT 250 WORDS)