Nerve growth factor affects defense-related behaviors, but not lordosis, in ovariectomized, estrogen-treated rats

Effects of NGF and anti-NGF on estrogen-sensitive behaviors were examined in ovariectomized, estrogen-treated rats. Intracerebroventricular (i.c.v.) administration of NGF resulted in a significant decrease in body weight. Daily treatment with low levels of estradiol resulted in a steady increase in lordosis behavior as reflected by average lordosis quotient and lordosis score. No effects of NGF or anti-NGF on lordosis behavior were detected. Estrogen treatment also resulted in a significant increase in the number of vocalizations elicited from female controls by male contact during sex behavior. NGF-treatment enhanced this effect, resulting in significantly more vocalizations elicited earlier in the course of estrogen treatment than were elicited from non-NGF-treated controls. These effects were blocked by progesterone. An increase in the number of rejections elicited by male contact during sex behavior was also observed in NGF-treated animals relative to controls. In addition, i.c.v. infusions of anti-NGF prevented the estrogen-mediated increase in elicited vocalizations, suggesting that NGF may have a physiological role in regulating this behavior. These data implicate NGF in the regulation of specific defense-related behaviors in estrogen-treated rats. Effects of NGF and anti-NGF on immunocytochemical staining for p75NGFR-, and ChAT-like immunoreactivity were also analyzed and are discussed.