Nitric oxide mediates caerulein-induced suppression of locomotor activity.
Caerulein, a non-selective agonist of cholecystokinin (CCK) receptors, is shown to suppress locomotor activity in rodents via stimulation of CCK(A) receptors. In the present study we examined the possible involvement of nitric oxide (NO) in caerulein-induced hypolocomotion in rats. Caerulein (10 microg/kg) markedly decreased the horizontal and vertical components of locomotor activity in rats measured in dark motility boxes. Pretreatment with a nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), at 5 mg/kg i.p., abolished the inhibiting action of caerulein on the horizontal activity, but did not affect the reduced frequency of rearing. The other doses of L-NAME (1, 10 and 20 mg/kg) were ineffective against caerulein. As L-NAME at this dose range does not stimulate locomotor activity, it is likely that NO is involved in the motor suppressant effect of systemically administered caerulein.
Volke
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Department of Physiology, University of Tartu, Estonia. vallo.volke@ut.ee
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Kõks
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Bourin
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Männistö
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D000704:Analysis of Variance; D000818:Animals; D002108:Ceruletide / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000819:agonists*
D004791:Enzyme Inhibitors; D011949:Receptors, Cholecystokinin; D009569:Nitric Oxide; D002108:Ceruletide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester