Effect of hCG on testicular steroidogenesis and gonadotropin and prolactin receptors in unilaterally cryptorchid rats.
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Animals↗
Biomedical subjects
A Bergh
Publications and source records attributed to A Bergh.
Differences in the regulation of steroidogenesis and tropic hormone receptors between the scrotal and abdominal testes of unilaterally cryptorchid adult rats.
Rats were made unilaterally cryptorchid by cutting the gubernaculum testis at birth. At 100 days age, the rats were injected with 600 IU/kg hCG. A biphasic testosterone response was seen in the scrotal (Scr) testis in response to hCG, with maxima at 1 h and 3 days after injection. The acute peak of testosterone was of similar magnitude in the abdominal (Abd) testis, but the secondary peak was not present. The response of testicular progesterone concentration to hCG stimulation showed a maximum at 1 day in both gonads, but it was 10- to 20-fold higher (P less than 0.01) in the Abd testis. The content of LH, FSH, and PRL receptors per testis was decreased on the Abd side. After hCG injection, the loss of available LH receptors was faster in the Abd testis. Likewise, the recovery of binding was faster in the Abd testes; at day 10 of the experiment, it was 102 +/- 5% of the starting levels compared to 52 +/- 4% on the Scr side (P less than 0.01). hCG did not affect FSH binding of the Scr testes, but induced a transient drop of 25-35% on day 1 on the Abd side (P less than 0.05). Thereafter, on days 3-10, the FSH binding of the Abd testes was 20-40% higher than on the Scr side (P less than 0.05-0.01). In PRL binding, similar heterologous down-regulation of 50-80% was found in both testes between 12-24 h. Thereafter, the Abd testis PRL receptors showed a transient elevation of 25-70% (P less than 0.05-0.01) on day 3, which was not seen in the Scr testes. In conclusion, the Abd testis displays a dramatically enhanced blockade of C21 steroid side-chain cleavage upon gonadotropin stimulation. The kinetics of changes in testicular LH receptors after hCG stimulation is faster in the Abd testis. Only Abd testes displayed hCG-induced changes in FSH binding and transient up-regulation of PRL receptors. The altered tropic regulation of Leydig and Sertoli cells of the Abd testis are indicative of direct functional changes in these cells in the elevated intra-Abd temperature and/or of changes in the paracrine component of testicular regulation.
Animals↗
Steroid biosynthesis and Leydig cell morphology in adult unilaterally cryptorchid rats.
Unilateral cryptorchidism was induced in newborn rats and when the rats reached adult age Leydig cell morphology and steroid biosynthesis were compared in scrotal and abdominal testes. The cell profile area of abdominal Leydig cells was reduced, the cytoplasm contained an increased number of lipid droplets and the endoplasmatic reticulum was more sparse than in scrotal Leydig cells. The intratesticular concentrations of progesterone, 20 alpha-dihydroprogesterone, 17 alpha-hydroxyprogesterone and testosterone were measured both basally and after LH stimulation. The synthesis of testosterone was subnormal in the abdominal testes. The data on basal steroid concentrations suggest a block at the 17 alpha-hydroxylase level, but observations after LH stimulation suggest that earlier steps are also involved. When studied in vitro the steroid biosynthesis in abdominal testes was also disturbed. The conversion mediated by 17 alpha-hydroxylase and 17 beta-ketosteroid reductase was lower and the conversion mediated by 20 alpha-dehydrogenase was higher in the abdominal testis. The reason for the disturbed steroid biosynthesis in abdominal testes is unknown. It may be related to the increased concentration of oestradiol in abdominal testes. Other possibilities are altered paracrine influence from the damaged tubules or changes in the microcirculation of the testis.
17-alpha-Hydroxyprogesterone↗
The acute effect of oestrogens on testosterone production appears not to be mediated by testicular oestrogen receptors.
Scatchard binding analysis was performed to measure the cytoplasmic oestrogen receptor in the testis of rats. After treatment of rats with the antioestrogen tamoxifen no oestrogen receptor binding was found in testicular low speed supernatant between 12 and 96 h after treatment. Such tamoxifen-treated rats were used to study the acute effect of oestrogens on testosterone secretion, both in vivo and in vitro. Injection of oestradiol benzoate (50 microgram, 24 h prior to experiment) resulted in a significant depression of basal and LH-stimulated plasma testosterone levels in control rats and this effect was unchanged in tamoxifen-pretreated rats. In vitro, oestradiol-17 beta also inhibited the LH-induced rise in testosterone secretion by isolated testicular interstitial cells. This inhibition was not affected if the rats had been pretreated with tamoxifen. These results indicate that the inhibitory effects of exogenous oestrogens on testicular testosterone production are probably not mediated by the oestrogen receptor.
Animals↗
Paracrine regulation of Leydig cells by the seminiferous tubules.
Testes of adult control and unilateral cryptorchid rats were fixed by vascular perfusion. The cell profile area of peritubular Leydig cells surrounding tubules in different stages of spermatogenesis, and the cell profile area of perivascular Leydig cells were determined. The size of peritubular Leydig cells was dependent on which type of tubulus the cells were surrounding. Some peritubular Leydig cells, especially those surrounding stages VII-VIII (88.1 +/- 7.1 micrometers2, mean +/- SD, n = 6 rats), were larger than perivascular Leydig cells (69.3 +/- 5.9 micrometers2). The size of Leydig cells surrounding stages IX-XIV was similar to that of perivascular cells. In the abdominal testes no spermatogenic cycle was present and the sizes of peritubular and perivascular Leydig cells were equal (63.0 +/- 5.1, vs 66.7 +/- 7.3 micrometers2, mean +/- SD, n = 5 rats). It is suggested that the tubules and the spermatogenic cycle locally modulate Leydig cell activity and that Leydig cell malfunction in abdominal testes may be due to a decreased stimulatory influence from the damaged tubules.
Animals↗
Early morphological changes in the abdominal testes in immature unilaterally cryptorchid rats.
Testicular descent was prevented unilaterally in newborn rats by cutting the gubernaculum testis. Morphological changes due to non-descent of the testes were studied in 16-, 20-, and 24-day-old rats. Scrotal and abdominal temperatures were measured in control rats, and a difference was noted from 16 days and onwards. At 16 days of age the abdominal testes showed an abnormal accumulation of lipid droplets in the Sertoli cells at certain stages of spermatogenesis, and the number of tubules which had developed a lumen was slightly greater than in the scrotal testes. At 20 days of age, some spermatocytes were degenerating in the abdominal testes, especially in the tubular segments where lipid accumulation had been seen earlier. Lipid accumulation was noted in the Sertoli cells in all stages of spermatogenesis and additional ultrastructural signs of Sertoli cell malfunction such as dilatation of the SER and dilatation of the intercellular space between adjacent Sertoli cells was observed. Also the number of tubules containing a lumen was slightly larger in the abdominal testes. At 24 days of age, the number of spermatocytes was reduced in abdominal testes and the morphological changes seen earlier in the Sertoli cells were more pronounced. The function of the blood-testis barrier was investigated by the ability of the tubules to exclude lanthanum, and no differences were found between scrotal and abdominal testes at 16 and 20 days of age. The present study suggests that the earliest morphological changes in experimentally primary abdominal testes may occur in the Sertoli cells.
Animals↗
Estrogen receptor and aromatase activity in the testes of the unilateral cryptorchid rat.
The intratesticular concentration of estradiol-17 beta (E2) is increased in the abdominal testis of rats made unilaterally cryptorchid at birth. To elucidate this observation testicular aromatase activity and testicular estrogen receptor concentration were studied. Aromatase activity was lower while the concentration of estrogen receptor was higher in the abdominal testis. Treatment of cryptorchid rats with the anti-estrogen Tamoxifen did not change testicular concentration of testosterone. However, Tamoxifen induced a significant reduction of E2 in the abdominal testis. The main factor responsible for the increased E2 concentration in the abdominal testis appears to be increased binding of estrogen.
Aging↗
Compensatory hypertrophy of the Leydig cells in hemiorchidectomized adult rats.
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Animals↗
Local differences in Leydig cell morphology in the adult rat testis: evidence for a local control of Leydig cells by adjacent seminiferous tubules.
In order to test the hypothesis that Leydig cell function in the adult rat testis is influenced by the surrounding tubules, Leydig cell morphology was compared in different types of interstitial areas. Triangular interstitial areas surrounded by 3 cross-sectioned tubules in nearly the same stage of spermatogenesis were chosen for quantitative light microscopy. It was found that the volume density of Leydig cells in such areas was about 30%, except when the surrounding tubules were in stages IX-X or XI-XII, when it was only about 20%. This variation in total Leydig cell mass seemed to be due to a variation in Leydig cell size and not in Leydig cell number. The largest Leydig cell profile area, 118 +/- 6 micrometers 2 (mean +/- SE n = 6 rats), was observed when the surrounding tubules were in stages VII-VIII, i.e. just prior to sperm release. The smallest Leydig cells were seen when the surrounding tubules were in stages IX-X and XI-XII (68 +/- 3 and 66 +/- 4 micrometers 2). The present results indicate that there may be a Leydig cell cycle in the adult rat testis, which is regulated by the adjacent tubules.
Animals↗
Morphological signs of a direct effect of experimental cryptorchidism on the Sertoli cells in rats irradiated as fetuses.
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Animals↗
How to avoid maternal cannibalism after neonatal surgery in rats.
Following surgery newborn rats are often eaten by their mothers. This can be avoided if the wound is closed carefully, the blood removed from the skin, and the wound area covered by a plastic film.
Animals↗
Decreased testicular response to acute LH-stimulation and increased intratesticular concentration of oestradiol-17 beta in the abdominal testes in cryptorchid rats.
Rats were made cryptorchid, bi- or unilaterally, by cutting gubernaculum testis at birth. At 100 days of age the basal plasma testosterone concentration was smaller in bilateral cryptorchid animals as compared to unilateral cryptorchid and control rats. After acute LH-stimulation plasma testosterone concentration increased in all rats, where the highest concentrations were found in the control group. The amount of testosterone in the testis after a 30 min LH-stimulation was lower in both kinds of cryptorchid testes but higher in the scrotal testis of the unilateral cryptorchid rats, all as compared to control testis. This decreased effect of LH observed in cryptorchid animals indicates an impaired Leydig cell function in cryptorchid testis. The results also show a compensatory hyperfunction of Leydig cells in the scrotal testes of unilateral cryptorchid rats. It was also found that the intratesticular concentration of oestradiol-17 beta was three-fold increased in unilateral cryptorchid testes and even more in bilateral cryptorchid ones.
Animals↗
Testicular blood flow and testosterone concentrations in the spermatic venous blood in rats with experimental cryptorchidism.
Testicular blood flow and testosterone concentrations in the spermatic venous plasma were measured on unilaterally cryptorchid rats. Blood flow to the cryptorchid testis was 31.4 +/- 11.7 (SD) ml/100 g X min which was significantly higher thant that of the scrotal testis (17.7 +/- 4.4 ml/100 g X min). Stereological analysis showed a relative increase of blood vessel containing interstitial tissue in the cryptorchid testis, which was probably the main factor responsible for the relative increase of blood flow to the cryptorchid testis. The increase of interstitial tissue was greater than the increase of blood vessels and thus, the interstitium in the cryptorchid testis contained a number of vessels which was smaller than that of the interstitium in the scrotally located testis. The concentration of testosterone in the spermatic vein of the abdominal testis was 18.0 +/- 5.5 (SD) ng/ml and the corresponding value for the scrotal testis was 41.2 +/- 7.0 ng/ml. Calculations based on functional and morphological data indicate that the function of the Leydig cells in the abdominal testis was impaired. It was concluded that the outflow of testosterone from the cryptorchid testis was highly reduced.
Animals↗
Morphologic changes induced by short-term ischemia in the rat testis are not affected by treatment with superoxide dismutase and catalase.
Short-term testicular ischemia was induced unilaterally by ligating the testicular artery for 60 or 100 minutes in adult rats. After 7 days, the rats were fixed by vascular perfusion. The effect of ischemia and reperfusion was quantified using morphometric techniques. Occlusion of the testicular artery for 60 and 100 minutes resulted in a mild and moderate damage, respectively, to the seminiferous tubules. The contralateral control testis was not affected. To study the role of oxygen radicals in ischemia-reperfusion-induced testicular damage, rats were treated with superoxide dismutase and catalase. These radical scavengers did not influence the extent of testicular damage.
Animals↗
HCG treatment increases intratesticular pressure in the abdominal testis of unilaterally cryptorchid rats.
Adult, unilaterally cryptorchid rats were given a single subcutaneous injection of hCG. HCG treatment of 100 I.U. (but not 10 I.U.) resulted in a marked increase in intratesticular pressure (approximately 40 mm Hg) in the abdominal testis that was maximal 24 hours after treatment. This increase in pressure is caused by increased vascular permeability coupled with insufficient lymph drainage. In the scrotal testis, hCG treatment resulted in increased vascular permeability and lymph flow, but this did not result in a marked increase in testicular pressure. No morphologic signs of hCG-induced damage were observed in either the abdominal or scrotal testis 10 days after hCG treatment. Testicular microcirculation, as studied by laser doppler flowmetry, was abnormal in the abdominal testis, but hCG treatment inhibited vasomotion in both the abdominal and scrotal testis.
Animals↗
Non-ortho PCB levels in various fish species from the east and west coast of Sweden.
Non-ortho (coplanar) PCBs 77, 126 and 169 were determined in a number of fish species from the Swedish coastal environment, using either supercritical fluid extraction (SFE) or the traditional liquid/liquid extraction followed by HPLC separation on porous graphitic carbon (PGC) column prior to GC/MS analysis. While PCB 77 showed the highest concentration level, the TEQ value for PCB 126 was dominant in virtually all the samples analysed. The toxic equivalents, however, indicated some differences in analytical data between 1990 and 1992/93 but these are not significant probably owing to the short period in between.
Animals↗
Microvascular testicular blood flow as evaluated by laser Doppler flowmetry after the surgical induction of varicocele.
This study was conducted to evaluate the changes in microvascular testicular blood flow (microvascular TBF), which may be associated with varicocele. The pathology was developed through partial ligation of left renal vein in 4 groups of rats. Controls of each group underwent sham surgery. It was observed that microvascular TBF dropped and its vasomotion became inhibited once the left renal vein was partially ligated as studied by laser Doppler flowmetry (LDF). Four to five minutes later, blood flow rose to the pretreatment level and that of controls. Vasomotion reappeared with a uniform frequency and amplitude. At different periods of varicocele bearing (1, 3, 6, and 14 weeks) microvascular TBF was reevaluated. Vasomotion appeared intact without any abnormalities in the 4 groups. To examine the response of testicular microvasculature after surgical creation of the varicocele to pharmacological stimulation another group of animals received human chorionic gonadotropin (hCG) treatment 6 weeks after varicocele creation. Vasomotion was inhibited in these animals. In conclusion, LDF is a suitable tool to evaluate microvascular TBF in vivo. It can detect acute changes in blood flow that may happen at surgical induction of varicocele. In addition, the vasculature of the testis with a surgically induced varicocele can still respond to hCG stimulation.
Animals↗
Leydig cell function and morphology in the rat testis after exposure to heat.
Leydig cell function, as judged from testosterone concentrations in plasma and in testicular tissue after LH stimulation, was tested in adult rat testes 4 days after brief exposure of the scrotum to 33 degrees and 43 degrees C, respectively. There was no significant difference in basal plasma testosterone concentrations between the two groups of rats but the response to LH stimulation was significantly depressed in rats exposed to 43 decrees C. Morphological examination of the Leydig cells showed an accumulation of lipid droplets in the cytoplasm of the testes exposed to 43 degrees C, indicating a disturbed steroidogenesis. The spermatogenetic arrest seen after heat treatment of the rat testis is discussed in relation to the present finding of impaired Leydig cell function.
Animals↗