Estrous cycle and sex differences in performance on anxiety tasks coincide with increases in hippocampal progesterone and 3alpha,5alpha-THP.
Sex differences and estrous cycle variations in anxiolytic-like behaviors and progestin concentrations were examined. Proestrous (n=22), estrous (n=19), diestrous (n=20), and male (n=18) Long-Evans rats were tested in horizontal crossing, open field, elevated plus-maze, emergence, holeboard, social interaction, tailflick, pawlick, and defensive burying tasks. Concentrations of plasma and hippocampal progesterone and 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP) were measured by radioimmunoassay in behaviorally tested (proestrus n=11, estrus n=8, diestrus n=9, male n=7) and yoked non-tested rats (proestrus n=11, estrus n=8, diestrus n=10, male n=8). Proestrous females exhibited more anxiolytic-like behavior than all other groups on the elevated plus-maze, social interaction, and defensive burying tasks. Proestrous females had significantly shorter latencies to emerge from a cylinder than did estrous and diestrous females, but not males. Proestrous and estrous females entered significantly more peripheral and total squares in a brightly-lit open field than did males. While proestrous females had a tendency to make more beam breaks than did males in the horizontal crossing task, there were no differences between groups on the holeboard task. There was a tendency for proestrous females to have longer tailflick latencies than diestrous and male rats; however, on the pawlick task there were no differences among the groups. Plasma and central progesterone and 3alpha,5alpha-THP of tested and non-tested rats were not different. Proestrous females had significantly higher plasma and hippocampal progesterone and 3alpha,5alpha-THP levels than all other groups. These data demonstrate that proestrous increases in anxiolytic-like behavior coincide with elevated circulating and hippocampal progestin concentrations.
Frye
C A
CA
Department of Psychology, SUNY-Albany, 1400 Washington Avenue, Albany, NY 12222, USA. cafrye@cnsunix.albany.edu
Petralia
S M
SM
Rhodes
M E
ME
D000818:Animals; D001007:Anxiety / Q000378:metabolism*; D001522:Behavior, Animal / Q000502:physiology; D003900:Desoxycorticosterone / Q000031:analogs & derivatives* / Q000378:metabolism*; D004971:Estrus / Q000378:metabolism*; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D011374:Progesterone / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D012737:Sex Factors
D003900:Desoxycorticosterone; C009413:tetrahydrodeoxycorticosterone; D011374:Progesterone