Male albino rats were permanently cannulated bilaterally in the caudate/putamen nucleus and subsequently injected unilaterally with cyclic AMP or cyclic GMP. Both of these cyclic nucleotides failed to produce any obvious change in motor activity. The concomitant intrastriatal injection of carbachol and cyclic AMP resulted in enhancement of the carbachol-induced dyskinesias. Under similar conditions, cyclic GMP blocked the carbachol effects. The dibutyryl (db) derivatives of cyclic AMP and cyclic GMP both enhanced the carbachol-induced dyskinesias and both db cyclic nucleotides induced dyskinesias when injected intrastriatally alone. The concomitant intrastriatal injection of dopamine and carbachol resulted in a blockade of the carbachol-induced dyskinesias. Dopmaine had no effect on db cyclic AMP and db cyclic GMP dyskinesias. The db cyclic AMP effects characteristically involved the distal limb musculature, while the db cycle GMP effects largely involved the proximal limb and trunk muscles. The hypothesis for opposing action of cyclic AMP and cyclic GMP in the CNS and the discrepancy between the effects of intrastriatal injection of cyclic AMP and dopamine were discussed.

Animals↗

PubMed1975

Motor effects of cholinergic stimulation of the globus pallidus in rats.

Forty-seven rats were cannulated permanently in either the globus pallidus or neostriatum and subsequently injected with carbachol, scopolamine, or carbachol plus scopolamine. The injection of carbachol (1 mug) into the globus pallidus produced transient hyperkinetic phasic dyskinesias (84%) followed in some cases by ipsilateral circling (47%) associated with hypertonic contralateral hind limbs. This condition progressed in some rats to a cataleptic state (42%). The injection of scopolamine (50 mug) or scopolamine (50mug) plus carbachol (1 mug) into the pallidum produced ipsilateral circling associated with hypotonia of the contralateral hind limb in a few rats. No hyperkinetic dyskinesias nor catalepsy were produced by these injections. The injection of carbachol (1 mug) into the neostriatum produced hyperkinetic dyskinesias (86%) of long duration, minimal circling (both directions) (10%), and catalepsy (29%). These effects were blocked by the addition of 50 mug of scopolamine to the carbachol injection. Scopolamine (50-100 mug) alone produced no effects after injection into the caudate/putamen. Saline injections in the neostriatum or globus pallidus produced no motor disturbance.

Animals↗

PubMed1974