A study of central neurotransmitter mechanisms in morphine-induced 'Straub reaction' in mice: role of central dopamine receptors.
1. The role of putative neurotransmitters was investigated in morphine-induced Straub reaction (SR) in albino mice. 2. Apomorphine (15 mg/kg) was also effective in inducing SR. However, in a smaller dose (0.2 mg/kg) it blocked SR induced by morphine. 3. Morphine-induced SR was potentiated by tranylcypromine, reserpine (acute effect), imipramine and L-dopa and blocked by reserpine (chronic effect), alpha-methyldopa, pimozide, chlorpromazine, haloperidol and metoclopramide. Prazosin and clonidine partially blocked morphine SR in high doses. 4. Propranolol, yohimbine, cyproheptadine and atropine were ineffective in blocking morphine SR. 5. The results indicate that morphine SR is mediated through release of DA in the CNS which excites central D2 receptors. Activation of central alpha 1-adrenoceptors might also play a minor role.
Gupta
M L
ML
Department of Pharmacology and Therapeutics, K.G.'s Medical College, Lucknow, India.
Nath
R
R
Gupta
T K
TK
Gupta
G P
GP
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000502:physiology; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013623:Tail / Q000294:innervation / Q000502:physiology*
D015259:Dopamine Agents; D018377:Neurotransmitter Agents; D011954:Receptors, Dopamine; D009020:Morphine; D001058:Apomorphine