Baclofen pretreatment prevents behavioral and molecular changes induced by morphine conditioned place preference in male, but not in female mice.

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

Congreso; XLVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE FARMACOLOGÍA EXPERIMENTAL. REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIA.; 2016

It is known that sex differences exist with respect to various pharmacological responses of morphine (MOR). Previous studies from our laboratory showed sex differences in the behavioral, molecular and neurochemical responses to MOR withdrawal syndrome and they were related to an increased sensitivity to MOR effects in males. In addition, baclofen (BAC), a GABAB receptor agonist, was able to prevent the somatic expression and the molecular and neurochemical changes induced by MOR withdrawal syndrome in mice. On the contrary, little is known about BAC effects on the reinforcing properties on MOR in male and female mice. Taking this into account, the aims of the present study were: 1) to evaluate the effect of BAC pretreatment in the conditioned place preference (CPP) induced by MOR in prepubertal male and female mice; 2) to analyze the effect of BAC pretreatment in the expression of BDNF induced by the reinforcing effects of MOR (7 mg/kg, sc) in prepubertal male and female mice in order to rule out the influence of sexual hormones. The CPP paradigm consists in three phases: pre-conditioning, conditioning and post-conditioning. Brains were obtained by transcardial perfusion immediately after the post-conditioning session to perform BDNF immunohistochemistry. Our results showed that MOR administration was able to induce CPP in both male and female mice (p