title: Allopregnanolone promotes success in food competition in subordinate male rats.
abstract: OBJECTIVE
  Allopregnanolone or 3α-hydroxy-5α-pregnan-20-one (AlloP) is normally sedative and anxiolytic, but can under provoking circumstances paradoxically induce aggressive behavior. Therefore, it is of particular interest to determine if there is a relationship between an anxiolytic effect and aggressive behavior following AlloP administration.
  
  
  METHODS
  Male Wistar rats were housed in triads comprising of 1 young rat (35 days) and 2 older rats (55 days), with the intent of producing a social hierarchy. The triads were sampled for total serum testosterone and submitted to a social challenge in the form of a food competition test (FCT), where the rats competed for access to drinking sweetened milk. At baseline, the younger rats were identified as subordinates. To test for the behavioral effect of AlloP, the subordinate rats were given intravenous AlloP injections of 0.5 and 1 mg/kg. To assess the optimal AlloP effect, 6 intervals (5, 10, 15, 20, 30 and 40 min) between injection and the FCT were used. In separate studies, AlloP was also given by subcutaneous and intraperitoneal administration at 10 and 17 mg/kg.
  
  
  RESULTS
  AlloP (1 mg/kg, i.v.) increased drinking time and aggressive behavior in subordinate rats, with a positive correlation between these behaviors. The subcutaneous injection (17 mg/kg) also increased drinking time in subordinate animals. Serum testosterone concentration was higher in dominant compared to subordinate rats, and correlated with drinking time and weight.
  
  
  CONCLUSIONS
  AlloP increased drinking time and aggressive behavior, and the correlation indicates a relationship between an anxiolytic effect and aggressive behavior.
authors.affiliation: Division of Obstetrics and Gynecology, Department of Clinical Sciences, Umeå Neurosteroid Research Center, Umeå University Hospital, Umeå, Sweden. magnus.lofgren@obgyn.umu.se
authors.forename: Magnus
authors.initials: M
authors.lastname: Löfgren
authors.forename: Sara K
authors.initials: SK
authors.lastname: Bengtsson
authors.forename: Maja
authors.initials: M
authors.lastname: Johansson
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Bäckström
mesh_terms: D061605:Administration, Intravenous; D000374:Aggression / Q000187:drug effects*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D003163:Competitive Behavior / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000187:drug effects*; D006608:Hierarchy, Social; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D008297:Male; D011280:Pregnanolone / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013256:Steroids / Q000008:administration & dosage / Q000494:pharmacology*; D013739:Testosterone / Q000097:blood; D013997:Time Factors
chemical_list: D014151:Anti-Anxiety Agents; D013256:Steroids; D013739:Testosterone; D011280:Pregnanolone