Comparison of motor depressant effects of caerulein and N-propylnorapomorphine in mice.
The motor depressant effects of caerulein and N-propylnorapomorphine (NPA) were compared in male mice. Caerulein (1-50 micrograms/kg SC) in a dose dependent manner depressed the exploratory activity, whereas NPA in lower doses (0.5-10 micrograms/kg SC) decreased the motor activity, but in higher doses (over 50 micrograms/kg) had stimulating effect on the exploratory behavior. In mice selected according to their motor response after administration of 100 micrograms/kg NPA to weak and strong responders, the low dose of NPA (1 microgram/kg) similarly suppressed motor activity in both selected groups, while the effect of caerulein (2 micrograms/kg) was apparently higher in weak responders. Destruction of catecholaminergic terminals by 6-hydroxydopamine (60 micrograms ICV) reversed completely the motor depressant effect of NPA, whereas degeneration of serotoninergic terminals (5,7-dihydroxytryptamine 60 micrograms ICV or p-chloroamphetamine 2 X 15 mg/kg IP) enhanced the sedative effect of NPA. The motor depressant effect of caerulein remained unchanged after lesions of monoaminergic terminals in forebrain. Subchronic haloperidol (0.25 mg/kg IP, twice daily during 14 days) treatment, reducing significantly the density of high-affinity dopamine2- and serotonin2-receptors, decreased the motor depressant action of caerulein. It is possible that motor depressant effect of caerulein, differently from the action of NPA, is mediated through the high-affinity dopamine2-receptors and in lesser extent through the high-affinity serotonin2-receptors.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002108:Ceruletide / Q000494:pharmacology*; D003864:Depression, Chemical; D005106:Exploratory Behavior / Q000187:drug effects; D010134:Fenclonine / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009411:Nerve Endings / Q000378:metabolism; D016627:Oxidopamine; D011954:Receptors, Dopamine / Q000187:drug effects; D011985:Receptors, Serotonin / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology; D013134:Spiperone / Q000378:metabolism
D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D011985:Receptors, Serotonin; D015116:5,7-Dihydroxytryptamine; D013134:Spiperone; C009074:N-n-propylnorapomorphine; D002108:Ceruletide; D016627:Oxidopamine; D006220:Haloperidol; D012844:Sincalide; D001058:Apomorphine; D010134:Fenclonine