Social stimuli augment estrogen receptor binding in preoptic area of female prairie voles.

In female prairie voles ovarian estrogen secretion is stimulated by exposure to males. The present study determined that social stimuli can also enhance the neural response to estrogen. Ovariectomized female voles given a fixed amount of estradiol and exposed to males had higher levels of estrogen receptor binding in cell nuclei in the preoptic area than did females given estrogen and not exposed to males.

Males increase progestin receptor binding in brain of female voles.

In female prairie voles, behavioral estrus is induced by exposure to an unfamiliar male and ovulation is induced by mating. Experiments were conducted to determine whether a saturable high-affinity progestin binding site (PRC) is present in cytosols of brain tissue from females exposed to male stimuli for a period of time which is sufficient to bring most females into heat. PRC were detected in both the medialbasal hypothalamus (MBH) and preoptic area (POA). However, PRC levels increased in response to male stimuli in the MBH but not in the POA. The lack of an increase in the POA could not be attributed to changes in circulating progesterone. These results indicate that social stimuli can influence cellular events within specific areas of the female brain and suggest that one distinguishing feature between the spontaneous and induced ovulators may be the pattern of estrogen-induced progestin receptors within areas of the brain which are involved with the control of sexual behavior and/or ovulation.

Males increase serum estrogen and estrogen receptor binding in brain of female voles.

Sexual development of female prairie voles does not occur unless females are exposed to stimuli from an unfamiliar male. Three experiments were conducted to determine whether a saturable high-affinity estradiol binding site (ERN) is present in cell nuclei of brain tissue from females exposed to male stimuli and whether serum estradiol and brain ERN are correlated with the duration of male exposure. Brain ERN were detected and found to be correlated with serum estradiol levels. Significant increases in brain ERN were observed within 18 hours after females were exposed to a male for either a continuous (uninterrupted) or transient (1 1/4 hour) period. A significant increase in serum estradiol was observed for females given continuous male exposure. The rate of increase of ERN in brain was significantly higher for females given continuous as opposed to transient male exposure. The results suggest that the continued presence of a male can accelerate the rate of increase of ERN in the brain, presumably through increases in circulating estradiol.

In vivo aromatization of [3H]testosterone in high and low mating lines of Japanese quail.

Japanese quail selected bidirectionally for adult mating frequency were utilized to study in vivo aromatization of testosterone (T) in relation to masculine copulatory behavior. Functionally castrated high (HM) and low mating (LM) line quail were injected with 75 microCi of [3H]T. One hour after the injection, all radioactivity recovered in telencephalic-diencephalic brain tissue was in the form of T, dihydrotestosterone (DHT), or estradiol (E2). Neither the total 3H nor the [3H]T metabolite radioactivity differed between the two genetic lines. Of all [3H]T metabolic radioactivity, [3H]E2 represented 45 +/- 6 % in the HM line and 46 +/- 6% in the LM line, indicating that the line difference in mating frequency was not due to a corresponding difference in aromatase activity. Inasmuch as both the HM and LM line birds actively converted T to E2, these results implicate a neural mechanism involving E2-receptor interactions as the cause of the behavioral differences between the HM and LM lines.

Blood proteins and amino acids of female breeder turkeys fed on maize-soybean diets supplemented with methionine.

Two hundred and six female breeder turkeys were fed on maize-soybean diets of equal energy content, containing 100, 120 or 140 g crude protein (CP)/kg to which DL-methionine was added at 0, 1, 2 or 3 g/kg diet in a factorial design. Serum albumin concentrations were found to be more sensitive measures of dietary protein adequacy than were total serum protein concentrations. Albumin concentrations at peak egg production were highest among birds fed on 120 and 140 g CP/kg diets. Four weeks later, they were highest only for those on the 140 g CP/kg diet. The elevated concentrations of blood threonine and lysine and the decreased concentration of glycine with increased dietary protein were in agreement with the data on egg production. These data suggested that a sub-optimal balance of dietary amino acids may have occurred.