Diet, hormonal, and metabolic factors affecting bone mineral density in adolescent amenorrheic and eumenorrheic female runners.

Seven adolescent female runners with secondary amenorrhea and six adolescent eumenorrheic female runners received dietary supplements of 1200 mg calcium carbonate and 400 IU vitamin D/d for 12 months. Bone mineral density (BMD) of the axial skeleton was measured by dual photon densitometry at the beginning and end of the 12 month period. Plasma estradiol and ionized calcium concentration were also determined. Bone mineral density decreased in two of the amenorrheic subjects, with the lowest estradiol values concurrent with the severest training regimen and highest calcium intake. There was a significant decrease in plasma estradiol concentration in the amenorrheic runners (p less than 0.05). Plasma ionized calcium and estradiol explained 99% of the variation in BMD (r2 = 0.999). A significant inverse relationship between plasma estradiol and miles run/week was observed (r2 = -0.748). Adolescent female runners who train extensively and have low plasma estradiol levels may be adversely affecting BMD despite supplemental calcium and vitamin D intake.

Developmental profile of plasma androgens in cockerels genetically selected for mating frequency.

Plasma levels of androstenedione (AE), testosterone (T), and dihydrotestosterone (DHT) were measured at 1, 56, 112, and 168 days of age by radioimmunoassay in lines of cockerels divergently selected for male mating frequency. Values for total androgen (total A = AE + DHT + T) were also computed. No significant differences in mean hormone values were found between lines at any age. Hormone patterns throughout development were also similar for both lines. Plasma AE and T increased between Days 1 and 56, stabilized through Day 112, and rose again prior to 168 days of age. In contrast, DHT levels were low throughout Day 112 and rose significantly by Day 168. Total A in the high mating line was low throughout Day 112 with significant increases occurring by Day 168. In the low mating line, total A was low on Day 1, increased significantly by Day 56, and it remained unchanged through Day 112. Peak values occurred by Day 168. Within line correlation analyses between AE, T, DHT, and total A revealed a more uniform hormonal state throughout development in the high mating line than in the low mating line. Because no differences were found between the mating lines in baseline levels of individual androgens or in concentration patterns of androgens up through the attainment of sexual maturity, it appears that neither posthatch baseline levels nor posthatch temporal androgen concentrations control male sexual behavior in the mating lines of birds.

Glucocorticoid concentrations, corticosteroid binding protein characteristics and reproduction performance of sows and gilts subjected to applied stress during mid-gestation.

Two experiments were conducted to evaluate the effects of applied heat (greater than or equal to 28 C) and crowding (less than or equal to .9 m2 floor space/animal) stress for 50 days during mid-gestation on glucocorticoid concentrations, corticosteroid binding globulin (CBG) characteristics and reproductive performance of 20 sows (Exp. 1) and 23 gilts (Exp. 2). Blood as collected via puncture of the anterior vena cava on days -1 and 0 before initiation of treatment and on days 1, 2, 12, 13, 48, 29 and 1, 5, 9 +/- l, 19 +/- 1, 50, 63 +/- 3, 90 +/- 1 after initiation of treatment for sows and gilts. respectively. Plasma glucocorticoids and CBG characteristics were determined by competitive protein binding techniques. Overall mean glucocorticoid concentrations for eight sows and 12 gilts subjected to stress were lower (P less than .05) than those of control animals, CBG binding capacities (CBC) were lower (P less than .05) in treated sows and gilts bled on days 12 and 9 +/- 1 after initiation of stress, respectively. Overall mean CBC and affinity (Ka) of cortisol to bind to the CBG molecule were lowered (P less than .05) in stressed gilts. Other than a reduction (P less than .05) in gestation length observed in stressed crossbred sows, reproductive performance was not affected by stress. When infrequent blood samplings are employed, measurement of CBC may serve as a more precise indicator of a physiological stress response than glucocorticoid concentration.