Vertes R P, Wu P H
Exp Brain Res. 1985;60(1):48-53. doi: 10.1007/BF00237017.
Adenosine and its analogs have previously been shown to exert a depressant effect on several measures of hippocampal excitability in the hippocampal slice and intact anesthetized preparation. In the present report, we examined the effects of intraventricular injections of adenosine analogs on hippocampal slow-wave activity in the freely moving rat. Each of three adenosine analogs-5'-N-ethylcarboxamidoadenosine (NECA) and N6-(phenylisopropyl) adenosine (L- and D-PIA)--were found to strongly suppress hippocampal electroencephalographic (EEG) activity. For instance, low doses of NECA (0.5 micrograms) produced an 80-90% decrease in the amplitude of the hippocampal EEG. NECA was approximately 20-fold more potent than L-PIA, and L-PIA was twice the potency of D-PIA. In separate experiments in the anesthetized rat, NECA and L-PIA were found to block completely the activation of the hippocampal theta rhythm elicited with brain-stem stimulation. The effects of adenosine analogs on both the hippocampal EEG and theta rhythm were very effectively reversed with methylxanthine, 8-para-sulphophenyl-theophylline (8-PSPT). The present findings demonstrate that adenosine analogs exert a powerful depressant effect on the hippocampal EEG in the natural unanesthetized state, and suggest that changes in the levels of endogenous adenosine may play a significant role in modulating the normal activity and function of the hippocampus.
腺苷及其类似物先前已被证明对海马切片和完整麻醉制剂中的几种海马兴奋性指标具有抑制作用。在本报告中，我们研究了脑室内注射腺苷类似物对自由活动大鼠海马慢波活动的影响。三种腺苷类似物——5'-N-乙基羧酰胺腺苷（NECA）和N6-（苯异丙基）腺苷（L-和D-PIA）——中的每一种都被发现能强烈抑制海马脑电图（EEG）活动。例如，低剂量的NECA（0.5微克）可使海马EEG振幅降低80-90%。NECA的效力约为L-PIA的20倍，而L-PIA的效力是D-PIA的两倍。在对麻醉大鼠进行的单独实验中，发现NECA和L-PIA能完全阻断脑干刺激引起的海马θ节律的激活。腺苷类似物对海马EEG和θ节律的影响可被甲基黄嘌呤8-对磺苯基茶碱（8-PSPT）非常有效地逆转。本研究结果表明，腺苷类似物在自然未麻醉状态下对海马EEG具有强大的抑制作用，并表明内源性腺苷水平的变化可能在调节海马的正常活动和功能中起重要作用。
