Alpha-1- and alpha-2-noradrenergic receptors modulate lordosis behavior in female guinea pigs.
Modulation of lordosis behavior by stimulation of noradrenergic receptor subtypes was examined in ovariectomized, estradiol benzoate (10 micrograms)-primed guinea pigs. In the first experiment, subcutaneous administration of the alpha-2-noradrenergic agonist, UK-14,304 (0.01, 0.5, or 1.0 mg/kg, Pfizer Central Research), produced a significant increase in lordosis behavior when these animals were compared with estrogen-primed control animals injected with saline. In a second experiment, estrogen-primed animals were injected with the alpha-1-noradrenergic agonist methoxamine (0.5 mg/kg, s.c.), UK-14,304 (0.5 mg/kg, s.c.), or both drugs given together. Methoxamine or UK-14,304 administered alone facilitated lordosis in fewer than 50% of animals (17 and 39%, respectively). However, when both drugs were given together, 76% of the animals became sexually receptive. A third experiment showed that lordosis behavior facilitated by UK-14,304 could be attenuated by the administration of the alpha-2-noradrenergic antagonist idazoxan (2.5 mg/kg, s.c.). Only 29% of sexually receptive animals (i.e. those animals primed with estradiol benzoate plus UK-14,304) continued to show lordosis after they received idazoxan. The results obtained from these and previously reported experiments suggest that both alpha-1- and alpha-2-noradrenergic receptors are involved in the regulation of lordosis behavior in the guinea pig.
Vincent
P A
PA
Institute of Animal Behavior, Rutgers University, Newark, N.J.
Feder
H H
HH
D000818:Animals; D000068438:Brimonidine Tartrate; D005260:Female; D006168:Guinea Pigs; D008729:Methoxamine / Q000008:administration & dosage; D010052:Ovariectomy; D010656:Phenylephrine / Q000008:administration & dosage; D011810:Quinoxalines / Q000008:administration & dosage; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*
D011810:Quinoxalines; D011941:Receptors, Adrenergic; D010656:Phenylephrine; D000068438:Brimonidine Tartrate; D008729:Methoxamine