Behavioral effects of interleukin-1 beta: modulation by gender, estrus cycle, and progesterone.
Endogenous release or exogenous administration of the cytokine Interleukin-1 (IL-1) produces several behavioral alterations, including suppression of locomotion and exploration. Because there are bidirectional interactions between IL-1 and the hypothalamic-pituitary-gonadal axis, we investigated possible differences between males and females in various phases of the estrus cycle in the behavioral effects of IL-1. In addition, we assessed the role of progesterone in mediating estrus cycle-dependent differences in these effects. Female rats in either the estrus or the non-estrus phase of their cycle and male rats were injected with either IL-1 beta (2 or 5 micrograms/kg) or saline. Activity in the open field test was measured 2 h later by counting the number of line crossings and rearings. In saline-injected rats, nonestrus females performed less line crossings than estrus females. IL-1 produced a significant dose-dependent reduction of line crossing in males and estrus females. In contrast, in nonestrus females the lower dose of IL-1 had no effect, and the effect of the higher dose was significantly smaller in nonestrus than in estrus females. The higher dose of IL-1 suppressed rearing in all three groups, but the effect of the lower dose on the number of rearings was significant only in estrus females. In a second experiment, ovariectomized females were injected with either progesterone (2 mg/rat) or oil, followed 2 h later by an injection of either IL-1 beta (2 micrograms/kg) or saline. Activity was measured continuously by a biotelemetric system. IL-1 reduced activity in progesterone-treated ovariectomized females but not in oil-injected controls. These findings suggest that changes in progesterone secretion along the estrus cycle modulate the behavioral responsiveness to IL-1 in female rats.
Avitsur
R
R
Department of Psychology, Hebrew University of Jerusalem, Mount Scopus, Israel.
Donchin
O
O
Barak
O
O
Cohen
E
E
Yirmiya
R
R
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001831:Body Temperature / Q000187:drug effects; D004971:Estrus / Q000502:physiology*; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D012727:Sex Characteristics
D007375:Interleukin-1; D011374:Progesterone