Unilateral Castration Research Articles

Androgen-dependence of ornithine decarboxylase in the rat epididymis

Ornithine decarboxylase (ODC) activity was measured in epididymides of 45-day-old rats. Higher ODC activity was detected in the corpus and cauda than in the caput epididymidis. Bilateral castration for 7 days caused epididymal ODC to fall to undetectable values, whereas testosterone restored activity to normal values. The effect of the androgen was significantly inhibited by cyproterone acetate. The caput was more sensitive to the action of testosterone than were the corpus and caudal segments. Unilateral castration for 4 or 8 days did not affect ODC on the control or castrated side, but the activity fell in epididymides of both sides after removal of the remaining testis. These results show that epididymal ODC activity is androgen-dependent.

Serum follicle stimulating hormone, luteinizing hormone, and testosterone in sexually stimulated intact and unilaterally castrated rams

Ten two-year-old intact (IN) and unilaterally castrated (UC) Targhee rams were exposed to an estrogenized ewe each week from June to October. Each week the rams were subjectively evaluated for libido (10 for high interest and 1 for no interest). Semen was collected from all cooperating rams and evaluated for volume, concentration, and motility. Every 2 wk, blood samples were obtained at −30 and 0 min before and 30 and 60 min after ewe access. Serum was harvested; follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone concentrations were quantified by radioimmunoassay (RIA). Week 5 of ewe access was assigned as Week 1. Libido scores rose from a low on Week 1, with eight rams ejaculating, to a high on Week 12, with all rams ejaculating (Week 1, 5.0 ± 1.0; Week 12, 10.0 ± 0.0). The product of testis length and width was significantly greater in UC compared with IN rams (88.4 ± 1.4 versus 73.2 ± 1.0 cm 2, respectively). Serum FSH concentrations (ng/ml) were greater (P < 0.05) in UC than IN rams and dropped over the experimental period. Serum LH concentrations (ng/ml) were significantly greater in UC compared with IN rams. This difference was more pronounced in Weeks 1 and 3 compared with Weeks 11 and 13. Serum testosterone concentrations (ng/ml) were similar in UC and IN rams throughout the experiment. In conclusion, serum testosterone was not altered in UC rams; however, serum FSH and LH concentrations were increased in UC rams. Unilateral castration did not enhance the normal changes in semen quantity and quality in the rams from July to October.

Effects of unilateral castration on morphologic characteristics of the testis in one-, two-, and three-year-old stallions

The effects of unilateral castration on testicular compensatory hypertrophy were measured in 12 Morgan stallions, four each at one, two, and three years of age. They were randomized within age to intact (IN) or unilaterally castrated (UC) groups. Allotment and surgery were in January 1983 and total castration was in June 1983, 150 d after unilateral castration. Testis weight increased linearly with age (P < 0.01) and was increased by unilateral castration (P < 0.07). Epididymal weight also increased linearly with age (P < 0.05) and was heavier in UC animals (P = 0.15). Tubule diameter (P < 0.10) and epithelial height (P < 0.03) were greater in UC than in IN stallions. In conclusion, testes of stallions underwent compensatory hypertrophy after unilateral castration.

Effects of unilateral castration on serum luteinizing hormone, follicle stimulating hormone, and testosterone concentrations in one-, two-, and three-year-old stallions

The endocrine control of compensatory hypertrophy was investigated in 12 Morgan stallions, four each at one, two and three years of age. Half were assigned to be unilaterally castrated (UC) in January and half to remain intact (IN). Nine blood samples were taken from each stallion at half-hour intervals 30, 90, and 150 d after unilateral castration for radioimmunoassay of serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone. Mean serum LH concentration was greater (P<0.06) in UC than IN stallions; however, the difference was greatest at 30 d and least at 150 d. Serum LH was greater (P<0.01) in two- and three-year-olds than in one-year-olds. The mean log 10 for serum FSH concentration was greater (P<0.06) in UC than IN stallions. Mean serum testosterone concentrations were similar in UC and IN stallions for all sample days, suggesting that the single testes of the UC stallions produced as much testosterone as the two testes of the IN stallions. Two- and three-year-old stallions had greater (P<0.01) serum testosterone than one-year-old stallions. Unilateral castration of stallions was associated with a significant increase in serum LH and FSH concentrations and, perhaps, higher intratesticular testosterone, which may explain, in part, the compensatory hypertrophy noted in the remaining testis.

Quantitative studies of compensatory testicular hypertrophy following unilateral castration in the boar.

Unilateral castration of Large White X Landrace boars at monthly intervals up to 5 months of age, with the remaining testis being removed 2 months later, resulted in compensatory hypertrophy of the testis which decreased with age. In pigs 3 and 4 months old there was significant hypertrophy of the testis but at 5 and 7 months of age testicular weight of the hemicastrates did not differ significantly from control values. The increase in the testicular weight of unilaterally castrated pigs was correlated with an increase in the number of Sertoli and germ cells at 3 months of age and germ cells at 4 months of age occupying the seminiferous epithelium. This was correlated with increased total seminiferous tubule length and larger cross-sectional area of the tubule. Sertoli cell occupancy did not differ significantly between unilaterally castrated and intact boars.

Effect of castration on plasma luteinizing hormone concentrations in prepubertal boars.

Mean concentrations and the occurrence of pulsatile release of luteinizing hormone (LH) were determined in 14-wk-old crossbred boars (50.5 +/- 1.5 kg) after bilateral or unilateral castration at 10 wk of age. Blood was collected at 10-min intervals for 5 h. Then gonadotropin releasing hormone (GnRH; 40 micrograms) was given and sampling was continued at 5-min intervals for 1 h. Compared with intact boars, bilateral castration increased (P less than .001) mean LH (982 +/- 56 vs 389 +/- 56 pg/ml), pulsatile releases of LH (7.0 +/- .6 vs 2.0 +/- .6 pulses/5 h) and LH pulse amplitude (617 +/- 29 vs 360 +/- 58 pg/ml). Unilaterally castrated boars did not differ from intact boars in any of the above measures of LH secretion. Testis weight increased more between 10 and 14 wk of age in the unilateral castrates than in the intact boars (432 +/- 42 vs 245 +/- 34%; P less than .05). Thus, compensatory hypertrophy occurred within 4 wk of castration. Plasma testosterone was lower for bilateral castrates than for intact animals (.1 +/- .8 vs 3.6 +/- .9 ng/ml; P less than .05) while unilateral castrates (3.8 +/- 1.0 ng/ml) and intact boars did not differ. Plasma estradiol concentrations in bilateral and unilateral castrates were not different from levels found in intact boars (1.8 +/- 1.8, 8.8 +/- 2.1 and 6.0 +/- 1.8 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Lateralization of LH-RH in rat hypothalamus

An asymmetrical LH-RH distribution in rat hypothalamus has been found. In Wistar rats LH-RH content in the right hypothalamus exceeds that in the left one; in albino rats a contrary distribution is observed. LH-RH lateralization changes during a 24-h period. Unilateral castration or cold stress lead to a shift in LH-RH distribution in the hypothalamus.

Effects of unilateral castration and unilateral cryptorchidism of the Holstein bull on plasma gonadotropins, testosterone and testis anatomy.

The effects of unilateral castration (UC) and induced unilateral cryptorchidism (CR) on plasma hormones and testis anatomy were studied in 36 Holstein bulls altered at either 3, 6 or 9 mo of age (n = 12). Plasma hormone concentrations were determined in six samples collected at hourly intervals on d 0, 1, 3, 7, 14 and 30, and then at monthly intervals through 6 mo after gonadal manipulation. Although plasma testosterone (T) showed a transient decrease (P less than .05) immediately after treatment, mean plasma concentrations of luteinizing hormone (LH) and T were unaffected by UC or CR over the 6-mo period (P greater than .05). Both hormones increased (P less than .05) in concentration with advancing age. Plasma follicle stimulating hormone (FSH) concentration was greater (P less than .05) in UC than in intact (IN) bulls overall, while FSH in CR bulls did not differ (P greater than .05) from either group. At slaughter, 11 mo after gonadal alteration, mean testis weight, ratio of testis weight to body weight and mean testis sperm cell numbers were increased (P less than .05) in UC bulls compared with mean testis values in intact (IN) bulls. Unilateral castration increased (P less than .05) seminiferous tubuler diameter and seminiferous epithelial cell height from basement membrane to the border of the lumen, but did not alter the ratio of tubuler to interstitial space within the testis. Seminiferous tubuler diameter and epithelial cell height were increased (P less than .05) in CR compared with IN bulls. Unilateral gonadal alteration at 3 mo of age caused a greater (P less than .05) hypertrophy of the scrotal testis in both UC and CR bulls than alteration at 6 or 9 mo of age. Results indicate that unilateral gonadal disruption is followed by rapid compensation in testis T production, little change in systemic LH and a rapid increase in secretion of FSH in the bull within those ages investigated. Further, UC elicits a greater compensatory hypertrophy than CR and the pituitary-testis endocrine axis is more responsive to alteration at 3 mo than at 6 or 9 mo of age in the bull.

Effects of unilateral castration and unilateral cryptorchidism of the Holstein bull on in vitro Leydig cell response.

The effects of unilateral castration (UC) and induced unilateral cryptorchidism (CR) on in vitro Leydig cell function were determined utilizing 36 Holstein bulls altered at either 3, 6 or 9 mo of age. Testes were removed 11 mo after gonadal manipulation and Leydig cells were dispersed in media containing 0 or 75 ng luteinizing hormone (LH). After incubation for 4 h, testosterone (T) concentration in the media was determined by radioimmunoassay. Leydig cells of UC animals produced greater (P less than .001) amounts of T than did Leydig cells of either CR or intact (IN) bulls with either 0 or 75 ng LH. Leydig cell T response was greater (P less than .001) in UC animals altered at 3 mo of age than in those altered at 6 or 9 mo of age. In a second experiment using only UC bulls altered at 3 mo of age, similar results were obtained. Leydig cells of UC bulls produced greater (P less than .05) amounts of T in vitro, both without LH or in response to 75 ng LH, than did Leydig cells of IN bulls at 10 mo after gonadal manipulation. Results indicate that UC in the bull causes increased Leydig cell capacity for T production in the remaining hypertrophied testis and this effect is greater when UC is performed at 3 mo of age than at 6 or 9 mo of age.

Testosterone, luteinizing hormone, follicle stimulating hormone, and prolactin response to unilateral castration in prepubertal Holstein bulls

Hemicastration of Holstein bulls at 3 months of age resulted in increased (P<0.005) testicular weitht and testis sperm cell content at 330 days after treatment, but did not alter sperm cell concentration in the remaining hypertrophied testis. Radioimmuroassay of blood hormones at 1, 6, 12, and 24 weeks after treatment revealed that unilateral castration did not alter (P>0.1) basal levels or GnRH response profiles of either LH or testosterone compared to intact bulls. Hemicastration caused FSH to be elevated (P<0.01) compared to intact bulls at all sampling periods in both unstimulated and GnRH stimulated bulls. Prolactin varied with season and was greater (P<0.001) in hemicastrated bulls than in intact bulls at 1 and 6 weeks after treatment. Results indicate that unilateral castration at 3 months of age caused testicular hypertrophy of both steroidogenic and gametogenic function and this phenomena may be triggered by increased FSH or prolactin secretion, or both. Further, results indicate different testicular regulation mechanisms exist for pituitary LH and FSH release in bulls.

Growth, differentiation, and function of the testes in the toad Bufo bufo bufo (L.), with special reference to regulatory capacities: effects of unilateral castration, hypophysectomy, and excision of Bidder's organs.

Function and compensatory growth of the testis have been studied in male toads of varying ages, ranging from postmetamorphosis to adults. All experiments lasted 2 months, starting about September 1. Spermatogenesis was normal in sexually immature, 1-year-old toads. The fastest growing young toads developed secondary sex characteristics, the thumbpads, during the experiment. The data suggest that size is more influential than age in determining the onset of sexual maturation. But body size is not the only factor which influences sexual maturation. The growth response of the remaining testis to unilateral castration decreased with increasing age and size of the toads. Two months after operation the remaining testis had reached the size of two testes in the young toads, whereas the testis showed no significant compensatory growth in the adult-sized toads, whether sexually immature or mature. Hypophysectomy reduced body growth in young toads and prevented a testicular growth response to unilateral castration. Young toads, but no adults, with excised Bidder's organs had larger testes than the control toads. In hypophysectomized, young toads spermatogenesis was still active 2 months after the operation.

Morphometric Studies of Compensatory Testicular Hypertrophy in the Rat after Hemicastration

The quantitative nature of the compensatory testicular hypertrophy following unilateral castration was examined in groups of immature Wistar-derived male rats hemicastrated at 10, 20, 30, 40 and 50 days of age and completely castrated 20 days later. Hemicastration resulted in compensatory hypertrophy of the remaining testis and it decreased as the animals aged. In 30-day-old rats compensatory testicular hypertrophy was 33% while at 70 days of age hypertrophy was reduced to 2%. The increase in testis weight of hemicastrated rats was correlated with an increase in total seminiferous tubule length and a larger cross-sectional area which was due in part to the greater number of germ cells per testis. Sertoli cell number did not increase significantly in the hemicastrated testis but more germ cells were associated with each Sertoli cell.

Effect of unilateral castration and unilateral cryptorchidism on gonadotropin and testosterone response to gonadotropin releasing hormone in the bull.

The effects of unilateral castration (UC) and induced unilateral cryptorchidism (UCR) on basal plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, and on the responses of these hormones to gonadotropin releasing hormone (GnRH), were investigated in bulls altered at 3, 6 or 9 months of age. Blood plasma was collected before and after GnRH (200 micrograms) stimulation approximately 1 year following gonadal manipulation. Neither mean baseline concentrations nor GnRH-induced increases in plasma testosterone were altered (P greater than .1) by hemicastration or UCR (P greater than .1). Both mean baseline LH and GnRH-induced LH release were greater (P less than .05) in bulls altered at 3 months of age than in bulls altered at 9 months of age. UC increased (P less than .05) plasma LH response to GnRH over that observed in intact bulls, but not above that in UCR bulls. UCR had no detectable effect on either baseline concentrations or GnRH-stimulated LH release. FSH was increased (P less than .05) in hemicastrates, while UCR had a variable effect on peripheral FSH: FSH was reduced (P less than .05) in UCR animals altered at 3 months of age but increased (P less than .05) in UCR bulls altered at both 6 and 9 months of age when compared to FSH in intact bulls. The results indicate that, compared with intact bulls, UC bulls release increased amounts of both gonadotropins but similar amounts of testosterone in response to GnRH stimulation. UCR had a variable effect on FSH release and did not alter either LH or testosterone.

Effects of short-term bilateral and unilateral castration and androgen replacement on the metabolism of [3H] testosterone in vitro by the epididymis of the immature rat.

The in-vitro metabolism of [3H] testosterone by the epididymis of the pubertal rat (55 days of age) has been examined after short-term bilateral and unilateral castration and androgen replacement. Bilateral castration did not decrease the metabolism of [3H] testosterone, but did result in a decline in the proportion of 5 alpha-dihydrotestosterone produced and an increase in that of 5 alpha-androstane-3 alpha, 17 beta-diol, androsterone and 5 alpha-androstane-3,17-dione. Changes in metabolism occurred in the caput within 2 days after surgery, but not until 5 days after surgery in the cauda epididymidis. Daily testosterone treatment, which maintained prostatic growth in bilaterally castrated animals, did not restore normal androgen metabolism and increased further the production of androsterone and 5 alpha-androstanedione by the cauda. In unilaterally castrated animals, androgen metabolism in epididymal tissue from the operated side was normal in the cauda but was indistinguishable in the caput from that of bilaterally castrated rats. These results indicate that (a) androgen metabolism by the caput, compared to that by the cauda, responds more quickly to androgen withdrawal and (b) that in the short term, normal androgen metabolism by the caput, but not the cauda, is dependent upon the presence of the ipsilateral testis. Furthermore, testosterone alone proved an inadequate replacement for bilateral castration which implies that the pubertal rat testis secretes additional compounds which are essential for normal function of the epididymis.

Effects of hemicastration and unilateral vasectomy on the remaining gonad and on the FSH, LH and testosterone blood concentration in bulls

The effects of unilateral castration and vasectomy on the weight and microscopic appearance of the contralateral testis and on the blood levels of testosterone, LH and FSH, were studied in German Fleckvieh bulls. Testicular weights were higher in hemicastrated bulls (P < 0.01) and unilaterally vasectomized bulls (P < 0.05) when compared to controls, 377 ± 45g (x ± s, N = 4 and 281 ± 12g, N = 4 vs 226 ± 38g, N = 3, respectively. Testosterone concentrations were higher during the weeks 14 to 22 after surgery in both treated groups. LH levels were not different from controls, but FSH levels increased significantly (P < 0.01) two weeks after hemicastration and unilateral vasectomy. Different factors appear to regulate the LH and the FSH concentrations in bulls. The increase of FSH after hemicastration may indicate a reduced production of inhibin or an inhibin-like substance from the testes, and a similar increase after unilateral vasectomy suggests that this substance may be resorbed distal to the testes.

Influence of unilateral castration and increased plane of nutrition on sexual development of Holstein bulls. I. Growth and sperm production

Sixty-five Holstein bull calves were used to study the effects of unilateral castration (UC) and increased plane of nutrition on the growth and development of the reproductive system. Bulls were slaughtered at 1 wk., 2, 4, 8 and 16 months. Half of each slaughter group above one week was unilaterally castrated at 7 days of age. Half of the bulls remaining at 6 months of age received 90% of their recommended daily TDN allowance while the remainder received 120%. Compensatory hypertrophy was evident as early as 2 months and the degree of compensation increased for the duration of the experiment (Age × UC, P<.01). By 16 months of age the remaining testis of UC animals was 73% heavier than the average testis weight of intact bulls. While epididymal weight was significantly increased by UC, seminal vesicle weight was not. UC bulls produced significantly more sperm per testis than intact bulls both from the onset of puberty to slaughter and for the 16 week period prior to slaughter. Testis sperm concentration was similar in UC and intact bulls. UC at one weel of age caused greater testis growth and greater sperm production per testis, but did not promote earlier puberty.

Influence of unilateral castration and increased plane of nutrition on sexual development of Holstein bulls. II. Histologic development of the testes

Sixty-five Holstein bull calves were assigned in an experiment to determine the effects of unilateral castration (UC) at 1 week of age and of two levels of nutrition after 6 months on reproductive development to 16 months. Five animals were killed at 1 wk and half the remainder UC at that age. Groups of 5 in all factorial groups were killed at 2, 4, 8 and 16 months. Tubular diameter increased with age (P<.01) and at 8 and 16 months with UC (P<.01). Epithelial area at 8 and 16 months increased with age and UC (P<.01). The percents of tubular and intertubular tissue varied with age (P<.01) with the tubular tissue having its highest value at 8 months. Indexes of both total tubular and intertubular tissue were increased with age and UC (P<.01). The number of type A spermatogonia per cross section of stage 1 tubules of 16-month bulls was increased by UC (P<.05).

Influence of unilateral castration and increased plane of nutrition on sexual development of Holstein bulls. III. Endocrine responses

Pituitary gonadotropic hormones were assayed in 65 Holstein bulls from 7 days to 16 months. Pituitary LH concentration and content at 2, 4, 8 and 16 months increased (P<.01) with age, while FSH content increased with age (P<.01) but was lower in UC bulls at 2, 4 and 8 months and higher at 16 months (A × UC, P<.01) as compared to intact bulls. In five samples of plasma collected at 90-minute intervals, one day each month from 1 to 15 months in 10 of the bulls killed at 16 months, LH concentration and variance changed (P<.01) with age reaching maxima at 4 and 3 months respectively. Plasma testosterone concentration and variance changed (P<.01) with age, reaching maxima at 10 and 9 months respectively. In the other 10 bulls killed at 16 months, assays of plasma collected before and after exposure to a teaser showed that stimulation increased LH by 20 minutes after exposure but LH declined by 60 minutes while testosterone was increased 20 (P<.05) and 60 (P<.01) minutes after exposure.

Hormonal and histological studies in a 61XXY bull.

A Friesian bull with bilateral testicular hypoplasia was diagnosed as having a pure 61XXY karyotype. The bull displayed normal sexual behaviour but was azoospermic. At 17 months, the animal's peripheral plasma androgen levels appeared to be lower than normal, and one testicle removed one month later showed small seminiferous tubules totally lacking in germ cells. The Leydig cell volume of this testis was well within the normal range but the tubule length was rather short. At 33 months of age an increase in peripheral plasma androgen levels was noted. In the remaining testis there had been both a considerable rise in Leydig cell volume and a fall in tubule length. These findings may be explained by the interaction of three factors; the effects of the abnormal karyotype, the increased maturity of the animal at 33 months and the reaction of the remaining testis to unilateral castration.

The influence of the testis on the fertilizing life of spermatozoa in the ligated vas deferens of the golden hamster.

Spermatozoa in the vas deferens of the hamster lose their fertilizing capacity 3 days after ligation of the initial part of the duct and after 2 days if the testes are removed at the time of ligation. Sham-ligation had no effect on the fertilizing life of vasal spermatozoa on the contralateral side even 3 days after bilateral castration. Unilateral castration for 3 days had no effect on the fertilizing capacity of spermatozoa from the ipsilateral unobstructed duct, whereas no eggs were fertilized by spermatozoa from the contralateral ligated duct associated with the remaining testis. Unlike testosterone, 5alpha-dihydrotestosterone injected daily or implanted subcutaneously in Silastic tubes maintained normal fertilizing capacity for 2 days in castrates and for 3 days in intact males. Within each group, ligation had no effect on the level of fructose in the seminal vesicle on that side compared with the level in the gland on the other side.