@article{juniewicz_welsh_johnson_1985, title={EFFECTS OF ZERANOL UPON BOVINE TESTICULAR FUNCTION}, volume={23}, ISSN={["0093-691X"]}, DOI={10.1016/0093-691X(85)90191-8}, abstractNote={Effects of zeranol upon testicular function in bulls were studied. In Experiment I, young bulls (104±1.7 days of age) were either implanted with 36 mg zeranol or served as controls with reimplantation on days 56 and 112 after first implant. After a 168-day treatment period, half the bulls were orchidectomized with the remaining bulls assigned to a 168-day recovery period, after which they were also orchidectomized. Zeranol inhibited testicular development during the treatment period. Testosterone (T) concentrations were lower (P<0.01) in treated bulls. Spermatozoa were absent in testes of treated bulls while control bulls averaged 27×106 sperm per gram of testis. At the end of the 168-day recovery period, testes weights and sperm concentrations were similar (P>0.10) between bulls previously treated with zeranol and controls. Implantation of older bulls with either 36 mg (267±3.4 days of age: Experiment II) or 72 mg (16 months of age: Experiment III) of zeranol had no effect (P>0.10) upon spermatogenesis or T production over a 168-day treatment period. The results indicate that the inhibitory effects of zeranol upon bovine testicular function are age-dependent and suggest that there may be an increased sensitivity of the hypothalmic-pituitary-testicular axis to zeranol in the prepuberal bull.}, number={4}, journal={THERIOGENOLOGY}, author={JUNIEWICZ, PE and WELSH, TH and JOHNSON, BH}, year={1985}, pages={565–582} }
 @article{juniewicz_johnson_1984, title={ABILITY OF CORTISOL AND PROGESTERONE TO MEDIATE THE STIMULATORY EFFECT OF ADRENOCORTICOTROPIC HORMONE UPON TESTOSTERONE PRODUCTION BY THE PORCINE TESTIS}, volume={30}, ISSN={["0006-3363"]}, DOI={10.1095/biolreprod30.1.134}, abstractNote={The influence of corticosteroids and progesterone upon porcine testicular testosterone production was investigated by administration of exogenous adrenocorticotropic hormone (ACTH), cortisol and progesterone, and by applying a specific stressor. Synthetic ACTH (10 micrograms/kg BW) increased (P less than 0.01) peripheral concentrations of testosterone to peak levels of 5.58 +/- 0.74 ng/ml by 90 min but had no effect upon levels of luteinizing hormone (LH). Concentrations of corticosteroids and progesterone also increased (P less than 0.01) to peak levels of 162.26 +/- 25.61 and 8.49 +/- 1.00 ng/ml by 135 and 90 min, respectively. Exogenous cortisol (1.5 mg X three doses every 5 min) had no effect upon circulating levels of either testosterone or LH, although peripheral concentrations of corticosteroids were elevated (P less than 0.01) to peak levels of 263.57 +/- 35.03 ng/ml by 10 min after first injection. Exogenous progesterone (50 micrograms X three doses every 5 min) had no effect upon circulating levels of either testosterone or LH, although concentrations of progesterone were elevated (P less than 0.01) to peak levels of 17.17 +/- 1.5 ng/ml by 15 min after first injection. Application of an acute stressor for 5 min increased (P less than 0.05) concentrations of corticosteroids and progesterone to peak levels of 121.32 +/- 12.63 and 1.87 +/- 0.29 ng/ml by 10 and 15 min, respectively. However, concentrations of testosterone were not significantly affected (P greater than 0.10). These results indicate that the increase in testicular testosterone production which occurs in boars following ACTH administration is not mediated by either cortisol or progesterone.}, number={1}, journal={BIOLOGY OF REPRODUCTION}, author={JUNIEWICZ, PE and JOHNSON, BH}, year={1984}, pages={134–142} }
 @article{juniewicz_toelle_robison_johnson_1984, title={VARIATION IN TESTOSTERONE PRODUCTION AMONG BOARS AND ITS RELATIONSHIP TO SEXUAL INTEREST AND BREEDING PERFORMANCE}, volume={22}, ISSN={["0093-691X"]}, DOI={10.1016/0093-691X(84)90483-7}, abstractNote={Variation in ability to produce testosterone in response to both GnRH and ACTH administration and quatitative relationships between GnRH-stimulated testosterone levels, ACTH-stimulated testosterone levels, sexual interest and breeding performance were assessed in a group of 31 Duroc boars (115.4 ± 2.5 kg body weight and 212.2 ± 3.0 days of age). Mean area beneath the testosterone response curve increased (P<0.01) after GnRH and ACTH but the magnitude of response was variable among boars. Post-GnRH testosterone area varied from 7.44 to 50.86 ng/ml X h with a CV = 52.41% while post-ACTH testosterone area varied from 4.99 to 28.78 ng/ml X h with a CV = 45.46%. Mean sexual interest and mean breeding performance scores were correlated (r = 0.67, P<0.01); however, correlations of either variable with testosterone areas were low and nonsignificant. These results indicate that the testosterone-producing ability of boars of similar age and breeding is highly variable and suggest that peripheral testosterone concentrations may not be good indicators of either libido or breeding performance.}, number={3}, journal={THERIOGENOLOGY}, author={JUNIEWICZ, PE and TOELLE, VD and ROBISON, OW and JOHNSON, BH}, year={1984}, pages={259–268} }
 @article{juniewicz_johnson_1980, title={EPISODIC FLUCTUATION OF TOTAL ESTROGENS IN PERIPHERAL-BLOOD OF BULLS - EFFECTS OF ESTRADIOL-17-BETA ON LH AND TESTOSTERONE SECRETION}, volume={23}, ISSN={["0006-3363"]}, DOI={10.1095/biolreprod23.5.1029}, abstractNote={Fluctuations in peripheral concentrations of total unconjugated estrogens (F) and the response of luteinizing hormone (LH), testosterone (T), and total glucocorticoids (CC) to administration of exogenous estradiol-17#{216}(E2 ) were studied in the male bovine in two experiments. In Experiment 1 hourly blood samples were collected via jugular cannula from four puberal Angus bulls during 24 h preinfusion, 12 h infusion and 12 h postinfusion periods. Episodic fluctuations in peripheral concentrations of E, LII, T, and CC were observed during the 24 h preinfusion period; however, the only significant temporal relationship observed was between concentrations of LH at 1 h and concentrations of T at the subsequent hour (LAG- LH-T-CORR, r = 0.42). Infusion of E2 at the rate of 41.7 mg/h resulted in acute increases in circulating concentrations and areas beneath hormone profile curves for LH, T, and CC. During the postinfusion period, both LH and T areas were less than areas calculated for similar times during the preinfusion period. In contrast, GC areas were greater (P<0.10) during the postinfusion period than at similar times prior to infusion. Based on results of the first experiment, Experiment 2 was designed to compare the effects of E2 infusion on circulating levels of Lii, T, and CC between eight control and seven E2 -treated bulls. Blood samples were collected every 30 mm for a 6 h preinfusion period after which E2 or propylene glycol was continuously infused for 6 h at a rate of 16.7 mg/h. Samples were also collected for a maximum of 6 h postinfusion. Significant acute increases in circulating concentrations and areas of LH and T were observed in five of seven E2 -treated bulls. There were no changes in hormone levels of control bulls during infusion. Both LH and T areas were not significantly different between F2 -treated and control bulls during the postinfusion period. Infusion of F2 did not influence levels of circulating CC and areas of CC. These results demonstrate that E can be included with LH, T, and CC as hormones whose peripheral concentrations fluctuate in an episodic manner. Also, administration of pharmacological levels of E2 can result in an acute increase in levels of circulating LH and T.}, number={5}, journal={BIOLOGY OF REPRODUCTION}, author={JUNIEWICZ, PE and JOHNSON, BH}, year={1980}, pages={1029–1037} }