Date of Award:

5-1975

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

LeGrande C. Ellis

Committee

LeGrande C. Ellis

Committee

James A. Jessaman

Committee

Warren Foote

Committee

R. P. Sharma

Committee

Thomas L. Bahler

Abstract

The regulation of the contractility and intratesticular pressure of rabbit testes was studied. The effects of, and interactions among, prostaglandins (PGs) E1 and F2α testosterone, acetylcholine, epinephrine and norepinephrine were ascertained both in vitro and in vivo. All of these compounds, except for high concentrations of PGE1 and testosterone, stimulated the testicular capsule to contract. PGE1 at low concentrations potentiated the contractions produced by epinephrine and acetylcholine. Above 10-7M, PGE1 inhibited contractions caused by PGF2α epinephrine or acetylcholine. Testosterone inhibited contractions caused by PGF2α in vitro.

Preinjections of rabbits with the PG synthetase inhibitor, indomethacin, significantly reduced testicular contractility in vivo. A second inhibitor of PG synthetase, 5,8,11,14-eicosatetraynoic acid (TYA), had no such effect. Reserpine failed to alter testicular contractions in vivo. Attempts to stimulate the spermatic nerve electrically using Ag-AgCl electrodes did not alter intratesticular pressure.

Exposing male rabbits to females had no significant effect on testicular contractions in vivo or in vitro. Serum testosterone measurements were made after injections of indomethacin, TVA, reserpine and combinations of indomethacin and PGE1. No significant changes were noted among groups due to large variability.

Intratesticular pressure showed spontaneous, rhythmical fluctuations in some preparations. Intravenous injections of norepinephrine increased overall pressure, whereas isoproterenol decreased it. The inhibition of rhythmical pressure changes after iv infusion of isoproterenol persisted at least half an hour. During this time norepinephrine failed to increase intratesticular pressure.

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