Abstract
The involvement of 5-HT in morphine-induced electrophysiological changes in the caudate nucleus and substantia nigra was examined in freely behaving rats. It was found that morphine treatment modified differently the sensory-evoked responses in these two structures. After tryptophan pretreatment, morphine induced in the substantia nigra the same responses as observed in the caudate nucleus after morphine alone. Cinanserin pretreatment blocked morphine-induced changes only in the substantia nigra, while PCPA had almost no effect in that site. In the caudate nucleus, the opposite phenomena were observed i.e. cinanserin pretreatment did not modify the morphine effect, although PCPA reversed the morphine-induced changes. An increase in morphine dosage overcame the PCPA effect on its action in both structures. These observations indicate that 5-HT plays an important role in morphine action. It can then be assumed that the caudate nucleus and substantia nigra have different functional properties in relation to morphine action that could be complementary or compensatory.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
