Sex Differences in Progesterone Effects on Responses to Stress and Drug Cues

Cocaine dependence is a chronic, relapsing disorder in which stress/negative mood and exposure to drug-related stimuli or "cues" are associated with high rates of relapse (McKay et al., 1995; O'Brien et al., 1998; R. Sinha, 2001; Shaham et al., 2003). In particular, sex differences in relapse precipitants have been noted, with women reporting greater stress related relapses while men report higher number of relapses associated with drug cue/temptation situations (Lex, 1991; McKay et al., 1996; R. Sinha, 2001; R. Sinha, Rounsaville BJ, 2002). Current SCOR studies have shown that stress and cocaine cues increase drug craving and stress related arousal, responses that differ in cocaine men and women (R. Sinha et al., 2003; H.C. Fox et al., 2005a). Furthermore, stress-induced cocaine craving and HPA responses are predictive of cocaine relapse, which is also moderated by gender (R. Sinha et al., 2006). However, no previous research has examined the basis of sex differences in stress and cue induced craving and arousal, both of which are known to increase relapse susceptibility. Greater knowledge of the sex-specific neurobiology of cocaine dependence will facilitate development of gender-specific cocaine relapse prevention efforts. Growing evidence supports a role for gonadal hormones in explaining the sex differences observed in stress responses as well as in the behavioral responses to cocaine (Festa \& Quinones-Jenab, 2004; K. Carroll, Fenton LR, Ball SA, Nich C, Frankforter TL, Shi J, Rounsaville BJ, 2004; Lynch, 2006; Kajanti \& Phillips, 2006). Estrogen increases behavioral responses to cocaine, while presence of progesterone decreases subjective and behavioral effects of cocaine, more so in females than males (Jackson et al., 2006; Sofuogu et al., 1999; M. Sofuoglu et al., 2002; Evans \& Foltin, 2006). Stress and cocaine each enhance brain stress circuits, namely the corticotrophin releasing factor (CRF)-hypothalamic-pituitary-adrenal (HPA) axis and central noradr