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Differential involvement of 5‐hydroxytryptamine 1A (5‐HT 1A ) receptors in the antinociceptive effects of hyperbaric oxygen (HBO 2 ) and nitrous oxide (N 2 O) in mice
Author(s) -
Winkle Christina K,
Rich Roxanne M,
Chung Eunhee,
Shirachi Donald Y,
Quock Raymond M
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.742.2
Subject(s) - nociception , chemistry , 5 ht receptor , pharmacology , agonist , receptor , serotonin , anesthesia , medicine , biochemistry
Earlier we reported that a 60‐min exposure to HBO 2 induced an antinociceptive response that lasted for up to 90 min following exposure [Zylstra et al ., FASEB J 22:711.17, 2008]. Recent studies have reported a sustained antinociceptive effect of a selective, high‐efficacy 5‐HT 1A receptor agonist in rodents [Deseure et al ., Eur J Pharmacol 568:134, 2007]. To determine whether supraspinal or spinal 5‐HT 1A receptors might be involved in HBO 2 ‐ or N 2 O‐induced antinociception, male NIH Swiss mice (20‐30 g) were exposed to HBO 2 (2.5 ATA, 60 min) then removed to room air for 90 min or N 2 O acutely (11 min). Mice were pretreated with intracerebroventricular (i.c.v.) or intrathecal (i.t.) selective 5HT 1A antagonist WAY‐100635 prior to antinociceptive testing using the abdominal constriction test. Results show that both i.c.v. and i.t. pretreatments with WAY‐100635 produced comparable and dose‐related antagonism of the antinociceptive response to HBO 2 . On the other hand, i.c.v. and i.t. pretreatment with WAY‐100635 had no effect on N 2 O‐induced antinociception. These results suggest that both supraspinal and spinal 5HT 1A receptors are involved in the 90‐min antinociceptive response to a 60‐min exposure to HBO 2 . However, there does not appear to be a role for 5HT 1A receptors in the antinociceptive response to N 2 O. (Supported in part by NIH Grant GM‐77153, the College of Pharmacy and the Chico Hyperbaric Center.)