PubMed Health⌕ Search

Biomedical subjects

B Barenton

Publications and source records attributed to B Barenton.

42 records · Page 3Linked to original sources
PubMed1982

Effect of cryptorchidism in the ram: changes in the concentrations of testosterone and estradiol and receptors for LH and FSH in the testis, and its histology.

Cryptorchidism was induced in 5 pre-pubertal lambs and 7 adult rams, 5 months after surgery, testicular weight and membrane protein content were 4-fold lower than in the control. The total number of Leydig cells per testis was markedly decreased but their size was not changed. In contrast, the total number of Sertoli cells per testis was not affected but their nuclear size was smaller. Induced cryptorchidism had no effect on the length of seminiferous tubules; blood vessel volume was reduced; and the production of germ cells was completely disrupted. The number of LH receptors estimated per Leydig cell was not changed in pre-pubertal lambs but decreased 4-fold in adult rams. The number of FSH receptors calculated per Sertoli cell was reduced by 95% in both pre-pubertal and adult animals. No effect on the binding affinities of LH (Ka = 1 X 10(10) M-1) and FSH (Ka = 4.5 X 10(9) M-1) to their testicular receptors was observed. Although testicular concentrations of testosterone and estradiol-17 beta were increased, the total content of testosterone within the testis was increased only in pre-pubertal lambs. The estimated ratio of testosterone per Leydig cell was higher in cryptorchid animals than in controls, suggesting that, despite their reduction in number and the decrease of LH receptors, the Leydig cells of cryptorchid rams have an enhanced steroidogenic capacity. This study also confirms the important dysfunction of the Sertoli cells in cryptorchid rams.

Animals↗
PubMed1982

Effects of induced hypoprolactinaemia in the ram: plasma gonadotrophin levels, LH and FSH receptors and histology of the testis.

In order to investigate the effects of induced hypoprolactinaemia on gonadotrophin levels and testicular function in the ram, CB 154 was administered either in summer under natural photoperiod or in winter combined with a light regime stimulating prolactin release. Under natural photoperiod in summer, plasma FSH levels increased from 2.5 to 4 ng/ml in controls and from 2.5 to 8 ng/ml in CB 154-treated rams. Control and treated groups differed significantly (P less than 0.05) from the second week of treatment onwards. In the animals photostimulated in winter, treatment with CB 154 did not change plasma FSH levels; no effect of CB 154 on plasma LH levels was detected in either experiment. Treatment with CB 154 in summer led to an increase in the volumes of peritubular blood vessels and interstitial tissue. The number of Leydig cells per testis was significantly (P less than 0.05) increased in CB 154-treated rams. However, at the time of measurement, there was no change in the structure of the seminiferous tubules or in the production of germ cells. In winter in photostimulated animals, no effect of treatment with CB 154 was detected either on the structure of intestitial and tubular compartments or on spermatogenesis. The change in prolactin levels affected neither the number of LH receptors, expressed per Leydig cell, nor the number of FSH receptors, expressed per Sertoli cell, in the experiments. It is concluded that induced hypoprolactinaemia can modify the release of FSH in the ram and change the structure of the intertubular tissue but that it does not affect the number of LH and FSH receptors or impair spermatogenesis.

Animals↗
PubMed1982

Influence of 2 Br-alpha-ergocryptine (CB 154) on the secretion of prolactin, LH, FSH and testosterone and on testicular growth in rams subjected to different photoperiods.

The influence of 2-Br-alpha-ergocryptine (CB 154) on the secretion of gonadotrophins and on testicular function has been studied in rams subjected to either a normal photoperiod or an abnormal photoperiod causing hyperprolactinaemia. The CB 154 treatment significantly lowered the mean frequency of LH and testosterone pulses in hyperprolactinaemic animals as compared to solvent-treated ones. Also, only those groups subjected to an abnormal photoperiod (groups 2 and 3) exhibited a significant rise in the frequency of LH and testosterone peaks after CB 154 was withdrawn. During treatment, plasma FSH concentrations increased significantly only in group 1 which was subjected to normal photoperiodic variations. Testicular growth was delayed in CB 154-treated rams compared to solvent-treated ones only in group 3 (hyperprolactinaemic).

Animals↗
PubMed1981

Failure of short-term hyperprolactinaemia to increase the number of gonadotrophin receptors in the ram testis.

Hyperprolactinaemia was induced during March in 2-year-old rams which had regressed testes. Five animals were intravenously infused with prolactin for 3 days at a rate that raised concentrations of prolactin in plasma to levels equivalent to those generally found in summer. Five untreated animals acted as controls. The treatment did not change plasma levels of LH and FSH and had no effect on testicular content of LH and FSH receptors. These results indicate that prolactin is not directly involved in the acute regulation of gonadotrophin receptors in the ram testis.

Animals↗
PubMedDate not supplied

Effects of experimental cryptorchidism and subsequent orchidopexy on seminiferous tubule functions in the lamb.

The reversibility of damage caused by cryptorchidism to the seminiferous tubules of the lamb was investigated at various ages. Lambs were made bilaterally cryptorchid either at birth or at 2 months of age. Then orchidopexy was performed at either 2 or 4 months of age. In permanently cryptorchid lambs, spermatogenesis stopped completely, and Sertoli cell function, as measured by FSH receptors, androgen receptors and ABP, was much reduced (-96%, -86% and -81%, respectively). Orchidopexy allowed the cryptorchid seminiferous epithelium to grow again, but the more differentiated the germ cells, the less they were capable of restoration. Even in 0- to 2- and 0- to 4-month-old temporarily cryptorchid lambs that had recovered normal Sertoli cell function, 16 to 49% of the tubules still were empty. It was concluded that cryptorchidism irreversibly damages the seminiferous tubules at a level other than the hormone receptors.

Age Factors↗