Effects of chlorpheniramine and hydroxyzine administration, as histamine H1- receptor antagonists, on the nociception threshold of cholestatic rats
Hormozgan Medical Journal: October 01, 2009, 13 (3); e88767
April 28, 2009
Article Type: Research Article
February 07, 2009
April 28, 2009
P. Effects of chlorpheniramine and hydroxyzine administration, as histamine H1- receptor antagonists, on the nociception threshold of cholestatic rats,
Hormozgan Med J.
Introduction: The elevated endogenous opioid tone in cholestasis is associated with
changes including an increase in the nociception threshold. We aimed to study the effect of
chlorpheniramine and hydroxyzine, H1-receptor antagonists, on modulation of nociception in
a model of elevated endogenous opioid tone, cholestasis.
Methods: Cholestasis was induced by ligation of main bile duct using two ligatures
and transsection the duct. Tail-flick latencies (TFLs) were measured at 30 minutes
after injection of chlorpheniramine (5, 10, 20 and 40 mg/kg, i.p.) and hydroxyzine
(6.25, 12.5,25 and 50 mg/kg, i.p.) during 7 days after the surgery.
Results: A significant increase (P<0.01) in TFLs was observed in cholestatics
compared to non-cholestatics. Chlorpheniramine (10, 20 and 40 mg/kg) and
hydroxyzine (12.5, 25 and 50 mg/kg) in cholestatic group significantly increased
TFLs compared to saline treated cholestatic group (P<0.05). Drugs injection in noncholestatics
did not alter TFLs compared to saline treated ones.
Conclusion: These data showed that systemic injection of chlorpheniramine and
hydroxyzine modulate nociception threshold in tone, as it does in the increased
activity of exogenous opioids. Perhaps, elevation of pain threshold in cholestatic rats
is a possible mechanism for the known antipruritic effect of these drugs.
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