title: Regional distribution of progesterone and 5 alpha-pregnane-3,20-dione in rat brain during progesterone-induced "anesthesia".
abstract: Progesterone and 5 alpha-pregnane-3,20-dione (5 alpha-DHP) concentrations were measured in seven brain areas and in plasma during "anesthesia" induced by progesterone (1-2 mg IV) in female rats. The highest levels of progesterone were detected in the striatum and hypothalamus (23.3 +/- 5.27 and 22.7 +/- 4.30 micrograms/g +/- SEM, respectively); these concentrations were approximately 1000 times higher than those during the post-ovulatory phase. Highest levels of 5 alpha-DHP were detected in the striatum and hippocampus (11.5 +/- 1.74 and 10.4 +/- 3.15 micrograms/g +/- SEM, respectively). The ratio of 5 alpha-DHP to progesterone was approximately 100 times higher in brain tissue than in plasma. We conclude that a conversion of progesterone to 5 alpha-DHP occurs in the brain during the course of progesterone-induced "anesthesia". This metabolic step may be an important contributory factor to the anesthetic potency of progesterone.
authors.affiliation: Department of Pathology, University of Umeå, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Bixo
authors.forename: T
authors.initials: T
authors.lastname: Bäckström
mesh_terms: D043582:5-alpha-Dihydroprogesterone; D000704:Analysis of Variance; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002531:Cerebellum / Q000032:analysis; D002540:Cerebral Cortex / Q000032:analysis; D003342:Corpus Striatum / Q000032:analysis; D005260:Female; D006624:Hippocampus / Q000032:analysis; D007031:Hypothalamus / Q000032:analysis; D008526:Medulla Oblongata / Q000032:analysis; D008636:Mesencephalon / Q000032:analysis; D011277:Pregnanediones / Q000032:analysis*; D011374:Progesterone / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D011277:Pregnanediones; D011374:Progesterone; D043582:5-alpha-Dihydroprogesterone