Synergistic Effects of Testosterone and Oestrogens on Accessory Sex Glands and Sexual Behaviour of the Boar

Abstract

The effects of oestrogens on the activity of accessory sex glands were studied in castrated boars receiving testosterone continuously. Diethylstilboestrol (DES), 17\g=b\-oestradiol(E2) and oestrone (E1) were administered successively for 6-week periods which alternated with treatments of testosterone alone. Semen was collected twice each week and measurements were made of the total, the strained and the gel volumes. Citric acid and fructose contents of the seminal plasma were also determined. Highly significant (P<0\m=.\01) differences between boars were observed for all criteria in a series of collections made before castration.Castration resulted in reduction in the total quantities of secretory products of the accessory sex glands. Subsequent treatment with testosterone alone for a period of 12 weeks had only a slight effect on their secretions. Supplementary treatment with DES, E2 or E1 significantly (P<0\m=.\01) increased the secretory activity of these glands from the levels in the respective preceding periods with testosterone alone. After withdrawal of oestrogens, the elevated levels of citric acid secretion remained high or increased further, while the amounts of seminal plasma and fructose continued at the higher levels or declined.Oestrogens also had a synergistic effect with testosterone on improving the libido of castrated boars. The reaction time was decreased by 45% (P<0\m=.\01)during supplementary treatment with oestrone for 12 weeks.The results of these experiments suggest that oestrogens act synergistically with testosterone on the accessory sex glands and on the sexual behaviour of the boar.

Return of testicular function after vaccination of boars against GnRH: consequences on testes histology

“…The latter finding might be due to a rebound phenomenon as it was also shown during pubertal development, where testicular function is optimized in a wave-like pattern until reaching the mature status (Allrich et al, 1983;Wagner and Claus, 2008). In contrast, weight of accessory sex glands is well known to be controlled by gonadal steroids, which include both testosterone and estradiol-17b in boars (Joshi and Raeside, 1973;Claus and Hoffmann, 1980).…”

Effects of age and live weight on the sexual development of gilts and boars fed two planes of nutrition

“…Cervix weight and length increased (P < 0.01) to a lesser extent ( x 1.4 and x 1.2, respectively) after puberty. (Joshi and Raeside, 1973 ;Morat et al 1980 ;Booth, 1980Booth, , 1983Lauwers et al, 1981) and undernutrition is known to reduce androgen production (Dickerson et al, 1964 ;Bonneau, 1987 (1983). However, the growth performances in the study of Den Hartog and Noordewier (1984) were similar to ours, while in that of Etienne et al (1983) gilts fed ad libitum had a slower growth rate so that they were one month older at 125 kg of live weight.…”

Metabolism of oestrone and oestradiol-17beta to conjugated steroids by the accessory sex glands of the male pig

“…As noted above, boars are remarkable for their high production of oestrogens by the testes and the secretion of large volumes of fluids from the accessory sex glands. Furthermore, our earlier work had suggested that oestrogens acted synergistically with testosterone on these glands ( Joshi & Raeside 1973). In the present study we have used younger animals which are known to respond to the high levels of testicular steroids seen in the postnatal period in the pig (Raeside et al 1997a, Schwartzenberger et al 1993.…”

“…It was concluded that a small supply of oestrogen appears to be favourable if not essential for the well-being of the male accessory reproductive organs. In more physiological terms, it was demonstrated later ( Joshi & Raeside 1973) that oestrogens act synergistically with testosterone on the accessory sex glands and on the sexual behaviour of the boar. Because the action of testosterone depends in such large measure on its further metabolism in target cells (Mainwaring 1977), we wished to determine to what extent the response to an oestrogen might similarly relate to its metabolism in the male reproductive system.…”