Plasma Luteinizing Hormone and Testosterone in the Adult Male Pig: 24 Hour Fluctuations and the Effect of Copulation

Abstract

Secretory patterns of LH and testosterone were characterized in the intact male miniature pig. All blood samples were taken from indwelling catheters. Hourly sampling was carried out over 24 h and during a morning period blood was collected for 2 h at 10 min intervals. No significant difference was detected in the plasma LH concentration on the basis of hourly sampling. Plasma testosterone was significantly (P less than 0-05) lower during the evening and night when compared with morning values. The second experiment was concerned with the pattern of plasma LH and testosterone concentrations before and after copulation. Blood sampling was performed at 10 min intervals. Plasma LH was significantly (P less than 0-001) raised for 30 min after copulation when compared with any 30 min period (0-120 min) before copulation. Plasma testosterone was not significantly altered for any 30 min period of the experiment (0-270 min). The data are interpreted as a possible mechanism for endocrine control of testicular function.

DIURNAL RHYTHM OF 5αANDROST-16-en-3-One AND TESTOSTERONE IN PERIPHERAL PLASMA OF BOARS

“…Low concentrations were observed in the evening until midnight and from morning till noon. This is in contrast to the observations of Andresen (1975) who reported no diurnal variations of the boar taint steroid 5a-androstenone in boars and to Ellendorff et al (1975) who found diurnal variations in testosterone in minipigs; however, there was only one peak (in the morning) and one minimal value (in the evening) per day. Since the feeding pattern in the latter ex¬ periment was similar to our own we cannot accept that there is an influence of the feeding time on the fluctuations.…”

“…of Animal Science, Clemson, South (Katangole et al 1971;Karg et al, in press), the roebuck') and the ram (Katangole et al 1974). In the miniature-boar Ellendorff et al (1975) found lower testosterone concentrations during the evening and night compared with morning values, similarly in man testosterone is higher in the morning and lower in the evening (Nieschlag 1974), whereas Sanwal et al (1974) found three distinct peaks per day in the bull.…”

Influence of Season and Social Environment on the Reproductive-Endocrine Status of the Adult Landrace Boar

“…The pattern of seasonal change in testosterone concentration paralled that in testicular length for these same boars (Trudeau and Sanford 1986) and concurs with an earlier report on the domestic boar (Claus et al 1985a (Sanford et al 1977;Sanford and Yarney 1983). LH and testosterone secretion is oulsatile in the boar (Ellendorff et al 1975;Sanford et al 1976). Although there is a cause-andeffect relationship between these secretions, not all LH pulses elicit an increase in testosterone secretion (Liptrap et al 1986 (Lincoln and Peet 1977;Sanford et al 1977Sanford et al , 1984 and may also play a regulatory role in the boar.…”

Effects of an Intravenous Injection of Tetracosactid on Plasma Corticosteroid and Testosterone Levels in Unstressed Male Rabbits

“…These two steroids were not separated but determined as total corticosteroids by a modified competitive protein-binding radioassay (Murphy 1967;modification: Vermeiden 1975 Testosterone plasma concentrations were measured by radioimmunoassay without chromatography (Ellendorff et al 1975) using an antiserum directed against testosterone-3-oxime-bovine serum albumine (Endocrine Science; Tarzana, Calif., USA). Out of 31 steroids tested by the supplier only dihydrotestosterone (44.0%), 5a-androstane-3/)', ß-dioì (3.0%), 5-androstene-3/i, ß-àiol (2.5 %) and -4-androstenedione (2.0%) significantly (more than I.O'/o) cross-reacted with this antibody.…”