Anxiety-related behavioural responses associated to morphine withdrawal syndrome: Sex differences in the expression of BDNF in mice

PEDRÓN VALERIA T.; VARANI ANDRÉS P.; BALERIO GRACIELA N.

Barcelona

Congreso; 8th FENS - Forum of Neuroscience; 2012

The Federetion of European Neuroscience Societies

Previous studies from our laboratory have shown an anxiolytic effect associated to morphine (MOR) withdrawal in male but not in female mice. On the other hand, baclofen (BAC), a GABAB receptor agonist, prevented this behavioural response. The aim of the present study was to evaluate the expression of brain derived neurotrophic factor (BDNF) in several brain regions in mice from both sexes after determining the anxiolytic response during MOR withdrawal and the prevention with BAC. Prepubertal Swiss-Webster male and female albino mice were treated with MOR (2 mg/kg, i.p.), twice daily for 9 days in order to induce animal´s dependence while another group of animals received saline. On the tenth day, a group of dependent mice received naloxone (NAL; 6 mg/kg, i.p.) 60 minutes after the last dose of MOR (Abstinent Group), and another pool of dependent animals received the pretreatment with BAC (2 mg/kg, i.p.) previous to NAL injection (Prevention Group). Immediately after the last injection, mice were placed on a plus maze in order to assess anxiety related behavioural responses during 15 minutes. After behavioral assessment, mice were sacrificed and brains were collected in order to perform inmunohistochemical labeling of BDNF. We observed a decrease in the expression of BDNF on the CA3 subregion of the hippocampus (p< 0,05), nucleus accumbens core (p< 0,05), bed nucleus of the stria terminalis (p< 0,05), cingulate cortex (p< 0,01), central amigdala (p< 0,05) and an increase in BDNF expression in basolateral amigdala (p< 0,01) in abstinent male mice. The higher intensity in the anxiety related behavioural response observed in male mice could be related to changes in the expression of BDNF during MOR withdrawal syndrome. Supported by Grants UBACyT B016 and PIP 11420090100303.