J. Anim Sci.
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J. Anim Sci. 1989. 67:1334-1340.
© 1989 American Society of Animal Science
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Control of Luteinizing Hormone in Postpubertal Boars with Large Testes1

P. L. Wolfe, M. W. Wolfe, T. T. Stumpf, J. A. Stotts2, M. L. Day3, R. J. Kittok, R. K. Johnson and J. E. Kinder4

University of Nebraska,5 Lincoln, NE 68583-0908

Abstract

The objective of the present study was to investigate endocrine control of LH in postpubertal boars with large testes. Eight boars with the highest estimated paired testis weights from a line selected for large testes and nine boars from a line selected at random were used. Blood samples were collected over a 13-h period at weekly intervals for 4 wk. Samples were collected at 12-min intervals for 12 h before and 1 h after exogenous LHRH. Boars were bled when they were intact during the initial week. The second and third blood collections were 7 and 14 d after castration. The fourth bleeding occurred 7 d after exogenous 17ß-estradiol (E2) replacement. In intact boars, mean LH was similar between boars from the two groups, but amplitude of pulses of LH was lower in intact boars with large testes than in boars from the control line. Maximum concentration of LH after administration of LHRH was less in boars with large testes than in boars from the control group. Seven days after castration, characteristics of LH measured did not differ between males from the two groups. However, 14 d after castration, amplitude of pulses of LH and maximum concentrations of LH after LHRH were less in males from the group with large testes than in males from the control group. After E2 administration, amplitude of pulses of LH tended to be lower in males from the group with large testes than in males from the control group. Therefore, amplitude of pulses of LH and responsiveness of the anterior pituitary to LHRH are suppressed in porcine males with larger testes compared with males from a control group both before and after castration.

Footnotes

1 Published as paper no. 8675, Journal Ser. Nebraska Agric. Res. Div. The authors thank K. Hannah, J. Ossenkop and L. Rife for assistance in preparation of the manuscript and Kenneth A. Pearson for technical assistance with hormone analyses. We also thank Gordon Niswender for the LH antisera; Norman Mason for estradiol antisera; and Leo E. Reichert for the purified LH used for iodination. This research was partially funded by the National Pork Producer's Council.

2 Present address: Syntex Co., 1321/2 N. Jefferson Ave., Pierre, SD.

3 Present address: Dept. of Anim. Sci., The Ohio State Univ., Columbus.

4 To whom reprint requests should be sent.

5 Dept. of Anim. Sci.






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Copyright © 1989 by the American Society of Animal Science.