CCK-8S systemic administration blocks the 7-nitroindazole-induced effects on the EEG of striatum and globus pallidus: a FFT analysis in the rat.

BACKGROUND Nitric oxide (NO) and cholecystokinin (CCK) are involved in the modulation of several neurotransmitter systems in the basal ganglia, and a functional interaction between their modulatory effects could be hypothesised. MATERIALS AND METHODS We studied the effects exerted by the administration of 7-nitroindazole (7-NI) (50 mg kg(-1) i.p.), a selective inhibitor of neuronal NO synthase, on the depth EEG activity of the striatum and of the globus pallidus in both not pre-treated and sulphated CCK octapeptide (CCK-SS)-treated (100 nM kg(-1) i.p.) rats. Striatal and pallidal depth EEG power spectra were examined by means of a Fast Fourier Transform analysis. RESULTS Striatal depth recordings showed a marked increase of % power of slow standard rhythms after 7-NI systemic treatment. In contrast, pallidal recordings revealed an increase of % power of rapid standard rhythms after i.p. injection of 7-NI. The same modifications were not evidenced in CCK-8S pre-treated rats after 7-NI administration. CONCLUSION The results show an influence exerted by peripheral CCK on the nitrergic modulation of the bioelectric activities of the striatum and of the globus pallidus. This effect could be of particular interest in the light of NO and CCK involvement in the neuroprotective mechanisms.