H. Davidowa et al., CHOLECYSTOKININ EXCITES NEOSTRIATAL NEURONS IN RATS VIA CCKA OR CCKB RECEPTORS, European journal of neuroscience, 7(12), 1995, pp. 2364-2369
The effect of iontophoretically applied cholecystokinin (CCK) on neuro
ns of the neostriatum was studied in rats anaesthetized with urethane.
The most frequently observed effect of the sulphated octapeptide (CCK
-8S) on striatal neurons was excitation. Spontaneously active neurons
responded more often to CCK-8S than quiescent cells. Silent, primarily
non-responsive neurons could often be stimulated with CCK-8S using gl
utamate to induce an ongoing discharge. Thus, 45.8% of the 177 neurons
studied changed their discharge rate by more than 30%, Certain CCK re
ceptor antagonists could prevent the effect of CCK-8S, fully or at lea
st partly, in the majority of CCK-responsive neurons. The data suggest
that cholecystokinin modulates the firing of active neostriatal neuro
ns via the CCKA or the CCKB receptor type. Furthermore, we compared ne
uronal responses to glutamate with those recorded during concomitant a
dministration of CCK-8S in order to study the interaction of both tran
smitters, which may be colocalized in striatal afferents, CCK-8S mainl
y enhanced the excitatory effect of glutamate on striatal neurons, but
in several neurons the response to glutamate was reduced. The CCKB re
ceptor antagonist could prevent CCK-8S from increasing the glutamate-i
nduced activation.