CROCIN (CROCETIN DI-GENTIOBIOSE ESTER) PREVENTS THE INHIBITORY EFFECTOF ETHANOL ON LONG-TERM POTENTIATION IN THE DENTATE GYRUS IN-VIVO

The effects of crocin (crocetin di-gentiobiose ester) and its analogs on long-term potentiation (LTP) of evoked potential in the dentate gyr us were investigated by using anesthetized rats. Intracerebroventricul ar injection of crocin (51.2 nmol) alone did not affect the synaptic p otential evoked by single stimulation of the medial perforant path, an d neither inhibited nor facilitated the LTP induced by strong (30 puls es at 60 Hz) or weak (20 pulses at 60 Hz) tetanus. Administration of e thanol (30 v/v%, 2 ml/kg i.v.) blocked the LTP induced by application of tetanus (30 pulses at 60 Hz), but the LTP-blocking effect of ethano l was prevented by preadministration of crocin (51.2 nmol i.c.v.). Cro cetin gentiobiose glucose ester also antagonized the LTP-blocking effe ct of ethanol, but it required a higher dose (102.5 nmol i.c.v.) to ex hibit a more significant effect than crocin. Crocetin di-glucose ester at a dose up to 102.5 nmol (i.c.v.) did not significantly affect the LTP-blocking effect of ethanol. Neither gentiobiose alone (102.5 nmol i.c.v.) nor glucose alone (204.9 nmol i.c.v.) mimicked the activity of crocin. These results suggest that crocin can prevent the ethanol-ind uced impairment of hippocampal synaptic plasticity in vivo and that ge ntiobioses attached to the fatty acid chain are important for crocin t o exert the biological activity.