Morphine attenuated the anxiety-like behaviour associated to acetic acid-induced visceral pain in adolescent male, but not in female mice lacking CB1 receptors.

CANERO ELIANA M.; PEDRÓN VALERIA T.; AON, AMIRA J.; VARANI ANDRÉS P.; BALERIO GRACIELA N.

Congreso; 11th FENS Forum of European Neuroscience; 2018

The aim of the present study was to evaluate the interaction between the CB1 cannabinoid receptors and the endogenous opioid system by assaying anxiety like-behaviour related to acetic acid-induced visceral pain in adolescent mice of both sexes lacking CB1 receptors.The elevated plus maze and acetic acid-induced writhing tests were used in order to evaluate the effect of morphine (MOR) on the anxiety like-behaviour associated to visceral pain. CB1 knockout (CB1 KO) and wild-type (WT) mice were pre-treated with MOR (3 mg/kg or 9 mg/kg i.p.) or saline (SAL) injection 20 minutes before acetic acid (1.5% i.p.) or SAL administration, and immediately after, the total number of writhes or anxiety-like responses were registered for a period of 20 min.MOR (3 mg/kg) decreased and MOR (9 mg/kg) completely blocked the nociceptive response (expressed as percentage of writhing inhibition) compared to their control groups (mice only treated with acetic acid) (p