Acute phenobarbital administration induces hyperalgesia: pharmacological evidence for the involvement of supraspinal GABA-A receptors
Braz. j. med. biol. res
;
34(3): 397-405, Mar. 2001. ilus
Article
in English
| LILACS
| ID: lil-281622
ABSTRACT
The aim of the present study was to determine if phenobarbital affects the nociception threshold. Systemic (1-20 mg/kg) phenobarbital administration dose dependently induced hyperalgesia in the tail-flick, hot-plate and formalin tests in rats and in the abdominal constriction test in mice. Formalin and abdominal constriction tests were the most sensitive procedures for the detection of hyperalgesia in response to phenobarbital compared with the tail-flick and hot-plate tests. The hyperalgesia induced by systemic phenobarbital was blocked by previous administration of 1 mg/kg ip picrotoxin or either 1-2 mg/kg sc or 10 ng icv bicuculline. Intracerebroventricular phenobarbital administration (5 æg) induced hyperalgesia in the tail-flick test. In contrast, intrathecal phenobarbital administration (5 æg) induced antinociception and blocked systemic-induced hyperalgesia in this test. We suggest that phenobarbital may mediate hyperalgesia through GABA-A receptors at supraspinal levels and antinociception through the same kind of receptors at spinal levels
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Phenobarbital
/
Spinal Cord
/
Receptors, GABA-A
/
Hyperalgesia
/
Hypnotics and Sedatives
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2001
Type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal de Minas Gerais/BR
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