Neurotropic effects of the optical isomers of the selective adenosine cyclic 3',5'-monophosphate phosphodiesterase inhibitor rolipram in rats in-vivo

The efficacy of the selective adenosine cyclic 3',5'-monophosphate (cAMP) phosphodiesterase (PDE) inhibitor (+/-)-rolipram and its optical isomers (0.006 to 25 mg kg-1) in inducing characteristic behavioural changes like hypothermia, hypoactivity, forepaw shaking, grooming and head twitches in rats has been examined. (+)-Rolipram was found some 15 times less potent than the racemate suggesting a stereoselective interaction with a rat brain cAMP phosphodiesterase isoenzyme. Following their intracerebral administration, the stereoisomers also demonstrated their unusual potency ratio. These findings suggested that (+)-rolipram is a less potent neurotropic PDE inhibitor in-vivo than its (-)-enantiomer.