LTP-blocking effect of ethanol

Fig. (3). Effects of crocin and its analogues on the LTP-blocking effect of ethanol.

A Time-course of potentiation of population spike amplitude. Saline (, 0) or CSE (250 mg/kg, A ) was orally administered 30 min before tetanus, and then saline ( ) or 30% ethanol (O.A ) was orally administered 10 min later (20 min prior to tetanus). B The dose-dependency of the influence of CSE on the LTP-blocking effect of ethanol. The numbers of observations are as follows saline alone (control), n=9 ethanol alone, n=8 ethanol and 125 mg/kg CSE, n=5 ethanol and 250 mg/kg CSE, n=ll. All data are represented mean SEM of n observations. p<0.0l vs. saline group (control). p<0.01 vs. ethanol alone (Duncan s multiple range test). 

When 30 % of ethanol (20 ml/kg) was administrated by the intravenous injection 10 min prior to tetanus blocked the induction of LTP. By the oral CSE (125 and 250 mg/kg) administrations 20 min prior to ethanol injection, the LTP-blocking effect of intravenously injected ethanol was significantly attenuated dose-dependently Fig. (8-A). Fig. (8-B) indicated the dose-dependency of the influence of CSE on the LTP-blocking effect of ethanol. The effect of CSE was also observed when ethanol was injected intracerebroventricularly [13],... 

We already indicated that intravenous injection of ethanol blocked the LTP induced by tetanic stimulation [18]. However, when saffron crude extracts were injected intracerebroventricularly, the blocking effect of ethanol on the LTP decreased dose-dependently [19]. Moreover, crocin prevents the ethanol-induced impairment of memory acquisition in ST and SD tests [20], From these results it is easily suggested that crocin antagonized the blocking effect of ethanol on the induction of LTP. 

An oral administration of crocin had no effect on memory acquisition in normal mice but improved the ethanol-induced impairment of learning behaviors of mice in passive avoidance performance tasks. This phenomenon resembled that of crude extract of saffron as reported previously. The tendencies of the effect between CSE and crocin are similar to each other. From these results it can be easily speculated that crocin is the most important principle in crude extract of saffron. Other crocetin glucoside esters weakly antagonized the blocking effect of ethanol on the LTP compared to crocin. 

Crocin of 50 mg/kg ameliorated the blocking effect of ethanol on the LTP at approximately 84% compared to the control as indicated in Fig. (10). Crocetin gentiobiose glucose ester also antagonized the blocking effect of ethanol on the LTP dose-dependently. But die intensity is not so strong, about a half of crocin when compared the intensity of 50 mg/kg. On the other hand, crocetin di-glucose ester did not remove the inhibitory effect of ethanol on the LTP. 

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