Isotretinoin (13-cis-retinoic acid) alters learning and memory, but not anxiety-like behavior, in the adult rat

Isotretinoin (ISO, 13-cis-retinoic acid) is commonly prescribed as Accutane for the treatment of acne. ISO is a known teratogen and the physical side effects of the drug have been well documented. However, possible psychological risks associated with the drug have yet to be determined. Retinoid receptors are abundant in the striatum and hippocampus, brain structures involved in implicit and explicit memory processes, respectively. The current study examined whether ISO influenced implicit or explicit memory processes using a two-stage radial-arm maze (RAM) task. The two stages were identical, except for the method of presenting arm choices to the rats: one at a time (Stage 1) or in pairs (Stage 2). Male rats (n = 12/group) were tested on both stages of the RAM during chronic oral treatment with ISO (0, 5, 10, or 15 mg/kg/day). Performance indicated that ISO impaired explicit memory in Stage 2, but retention tests one month after ISO exposure ended, indicated recovery from this explicit memory impairment and evidence of enhanced implicit memory in the 10 mg and 15 mg ISO rats. These data indicate extensive, enduring memory effects from oral ISO treatment at doses likely to produce serum levels within the range typically used to treat acne in humans.