title: Plasma progesterone levels and cocaine-seeking in freely cycling female rats across the estrous cycle.
abstract: Previous studies have reported sex and estrous cycle-dependent differences in the reinstatement of cocaine-seeking triggered by cocaine injections or drug-paired cues. However, the relationship between estradiol or progesterone levels and cocaine-seeking in a reinstatement model of relapse has not been explored. Thus, we examined changes in plasma hormone levels during cocaine-taking and -seeking behaviors in gonadally intact female rats. Rats self-administered cocaine (0.5mg/kg infusion) during daily 2-h sessions, followed by extinction. For reinstatement, cocaine (0, 5, or 10mg/kg, i.p.) was administered 30 min prior to testing. Vaginal smears and blood samples were collected prior to and during chronic cocaine self-administration, extinction, and reinstatement testing. Relative to non-estrous females, females in estrus showed greater responding during self-administration, extinction, and during cocaine-primed reinstatement. The highest progesterone levels were noted at the time of lowest cocaine-seeking (proestrus) and the lowest levels of progesterone occurred at the time of highest cocaine-seeking (estrus). In contrast, plasma estradiol levels did not show any clear pattern with cocaine-seeking. These data from an animal model of relapse supports recent clinical evidence that progesterone reduces subjective craving in cocaine-dependent women. Overall, these results suggest that progesterone administration may be a useful intervention for reducing the incidence of relapse.
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Feltenstein
authors.forename: Ronald E
authors.initials: RE
authors.lastname: See
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D003042:Cocaine / Q000008:administration & dosage; D019970:Cocaine-Related Disorders / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000502:physiology*; D005108:Extinction, Psychological / Q000502:physiology; D005260:Female; D009042:Motivation; D011374:Progesterone / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012646:Self Administration; D013223:Statistics as Topic
chemical_list: D011374:Progesterone; D004958:Estradiol; D003042:Cocaine