Antinociception induced by intracerebroventricular or intrathecal administration of gentamicin in rats.
1. The intrathecal (i.t.) administration of gentamicin (AD50 = 3.98 micrograms) produced marked and dose-dependent antinociception in rats, as assessed by the tail-flick test. A weaker effect was obtained following intracerebroventricular drug administration (AD50 = 50.12 micrograms). 2. A transitory but dose-dependent antagonism of the effect of i.t. gentamicin was obtained following i.t. administration of calcium chloride (4 and 8 micrograms). 3. The magnitude and duration of morphine antinociception (5 micrograms, i.t.) were enhanced by the previous (intraperitoneal) i.p. or i.t. administration of gentamicin. 4. These results indicate that gentamicin-induced antinociception may depend on its calcium-antagonist property and involves drug diffusion to a spinal site of action.
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Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, SP, Brazil.
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D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D004357:Drug Synergism; D005839:Gentamicins / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds / Q000187:drug effects
D000700:Analgesics; D005839:Gentamicins; D009020:Morphine; D002122:Calcium Chloride