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A. Bergh and J.-E. Damber

Summary. Treatment with hCG results in an increase in venular permeability in the rat testis. This change in vascular permeability can be detected by the carbon-labelling technique, by measurement of the volume of interstitial fluid and by quantification of the leucocyte migration into the interstitial space. Carbon-labelling, interstitial fluid volume and leucocyte migration were all reduced in rats treated with hCG + terbutaline compared to the values in animals given hCG only. However, terbutaline treatment did not influence the hCG-induced increase in testosterone secretion. These observations suggest that the hCG-induced increase in vascular permeability in the testis can be reduced by a β-adrenergic agonist.

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A. Bergh, J. E. Damber and A. Widmark

Summary. Adult male rats were injected with different doses of hCG, or with 2·5 μg ovine LH subcutaneously, and other rats were mated with oestrous females. The animals were examined 4 h after treatments. Treatment with hCG resulted in a dose-dependent increase in leucocyte concentration in testicular blood vessels and in the number of blood vessels which could be labelled with intravenously injected carbon particles. Carbon leakage was not observed in control testes. Treatment with a low dose of ovine LH or inducing an endogenous LH peak by mating also resulted in leucocyte accumulation and vascular leakage of carbon in the testis. The magnitude of the response was considerably lower than after high doses of hCG. The physiological relevance of the discrete response observed after physiological LH stimulation is unknown but LH-induced changes in testicular microcirculation could be of interest for the understanding of the physiology and pathophysiology of the testis.

Keywords: testis; LH; hCG; vascular permeability; inflammation

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Anna-Maria Hoffmann, A. Bergh and T. Olivecrona

Summary. A simple and reliable method was developed to determine the neutral cholesteryl ester hydrolase (CEH) activity in rat testes, using cholestery1-[1-14C]-oleate as substrate. The activity was due to a soluble enzyme present in the cytoplasm of predominantly Sertoli cells, which could be shown after depleting the testes of Leydig cells with ethane dimethyl sulphonate. This treatment also revealed that the loss of CEH activity in abdominal testes of experimentally cryptorchid rats takes place in the Sertoli cells. In prepubertal rats made unilaterally cryptorchid at birth, the CEH activity was significantly higher in the abdominal than in the scrotal testes at 16 days of age. This is earlier than any previously described biochemical change and coincides with, or may even precede, the earliest morphological changes which are accumulation of lipid droplets in the Sertoli cells. The testicular CEH activity then decreased to 30 days of age in the abdominal testes, whereas the activity increased in the contralateral, scrotal testes. When adult rats were made unilaterally cryptorchid for 24 h, the CEH activity decreased rapidly in the abdominal testes. These results suggest that a derangement in cholesteryl ester metabolism is an early event in the pathogenesis of testicular degeneration in cryptorchidism.

Keywords: testis; Sertoli cell; cryptorchidism; enzyme activity; assay; ethane dimethyl sulphonate

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O. Collin, J-E. Damber and A. Bergh

The effects of 5-hydroxytryptamine (5-HT), 5-HT2 receptor antagonists (ritanserin and ketanserin), histamine and substance 48/80 on testicular blood flow and microcirculation were studied in adult rats. The substances were administered by topical application on the testicular surface and by intratesticular injections, and blood flow was measured by radioactive microspheres and with a laser Doppler flowmeter. Blood flow was decreased by 5-HT in a dose-dependent manner and vasomotion in the testis was inhibited, suggesting that it could be involved in the physiological regulation of the testicular vasculature. The 5-HT antagonists did not significantly influence flow or vasomotion in intact testes. Histamine did not cause any major effects on testicular blood flow. Substance 48/80 caused degranulation of testicular mast cells, and reduced testicular blood flow and vasomotion suggesting that testicular mast cells, possibly by releasing 5-HT, could be involved in the local control of the testicular vasculature.

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O. Colin, A. Bergh, J-E. Damber and A. Widmark

Testicular vasomotion (rhythmical variations in testicular blood flow) was studied in adult rats using laser Doppler flowmetry. Vasomotion was not present in testes in which the Leydig cells had been destroyed, but it could be induced by a low dose of testosterone. Transposition of a scrotal testis into the abdominal cavity inhibited vasomotion and this was apparently not caused by Leydig cell malfunction. Depletion of specific germ cells (by unilateral X-irradiation induced killing of spermatogonia and maturation depletion of germ cells) did not abolish vasomotion in the testis. It is suggested that testicular vasomotion is influenced by testosterone and by factors from Sertoli cells.

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A. Bergh, P. Rooth, A. Widmark and J.-E. Damber

Summary. Adult rats were injected subcutaneously with 50 i.u. hCG and vascular permeability was compared to that in saline-treated control rats by two independent methods. At 4 h after hCG treatment the rats were injected intra-arterially (i.a.) with FITC-labelled macromolecular dextran (M r 150 000) and the testicular microcirculation was studied in vivo by using a fluorescence microscope. Other rats were injected i.a. with a suspension of colloidal carbon and the location of leaking blood vessels was recorded in sections from the testes by light and electron microscopy.

In hCG-treated animals leucocytes were found adhering to the endothelium in post-capillary venules and in these venular segments dextran was leaking into the interstitium. Carbon particles were deposited in the walls of post-capillary venules and leucocytes migrated through open interendothelial cell gaps in hCG-treated animals. In control animals leucocyte adhesion and migration were not observed, the injected dextran remained in the circulation and the blood vessels were not labelled by carbon.

It is suggested that the hCG-induced increase in testicular interstitial fluid volume, like the tissue oedema in inflammation, is caused by a leucocyte-mediated increase in venular permeability.

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U. Gerdes, M. Gåfvels, A. Bergh and S. Cajander

Summary. Colloidal carbon was injected i.v. in mature virgin rabbits at different times after induction of ovulation by human chorionic gonadotrophin (hCG, 100 iu) or mating. Before induction of ovulation, slight carbon leakage was observed in the inner vascular ring of the theca interna of antral follicles, but blood vessels in the other ovarian compartments were unstained. Between 4 and 10·5 h after hCG-treatment or mating, vascular leakage was most marked in the blood vessels of the interstitial gland and in the theca interna of antral follicles. Just before ovulation, carbon particles were observed between granulosa cells and some carbon was seeping into the follicular fluid of preruptured follicles. Vascular leakage was also observed over the follicle dome before rupture as well as at the dorsomedial junction between the mesovarium and the ovary. The blood vessels stained with carbon were 7–70 μm diameter, representing capillaries and postcapillary venules. About 6 h after hCG injection, an increased number of polymorphonuclear leucocytes migrated from the vessels of these ovarian compartments into the surrounding interstitial tissue. The number of leucocytes seen in the follicular wall and ovarian medulla increased markedly towards ovulation. During early corpus luteum formation, the number of leucocytes decreased markedly. The localized vascular changes seen after mating and hCG stimulation were similar to an inflammatory reaction and could form the basis for the formation of peritoneal exudate after ovulation in rabbits and periovulatory ascitic accumulation seen in the peritoneal cavity of women during the menstrual cycle.

Keywords: ovary; hCG; mating; vascular changes; leucocyte; ovulation; rabbit

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A. Bergh, H. Nikula, J.-E. Damber, R. Clayton and I. Huhtaniemi

Summary. Testicular descent was prevented unilaterally in newborn rats by cutting the gubernaculum testis. At 100 days of age, the number of Leydig and Sertoli cells per testis, the concentration of receptors for LH, FSH, prolactin and GnRH, and endogenous concentrations of progesterone and testosterone were determined. The weight of the abdominal testes was reduced by 80%, but in spite of this they contained as many Sertoli (32·8 ± 1·3 × 106, mean ± s.e.m., n = 6) and Leydig (28·2 ± 1·7 × 106) cells as did scrotal testes (32·1 ± 2·5 × 106 and 24·3 ± 1·2 × 106 respectively). The numbers of receptors for LH (3·2 ± 0·2 and 1·0 ± 0·2 pmol/testis, mean ± s.e.m., n = 11), FSH (358 ± 11·0 and 96·3 ± 12·6 fmol/testis) and prolactin (535 ± 32·7 and 92·4 ± 13·2 fmol/testis) were reduced (P < 0·001) in abdominal testes, but the number of GnRH receptors was unaffected (8·9 ± 1·4 and 12·1 ± 1·8 fmol/testis, n = 6). Testicular testosterone concentration (30·9 ± 4·4 vs 15·4 ± 3·2 ng/g, n = 11, P < 0·001), but not that of progesterone (0·87 ± 0·10 vs 1·01 ± 0·21 ng/g), was decreased in abdominal testes. The decreased receptor and androgen values reflect functional disturbances in the abdominal testes. The changed local milieu within abdominal testes may reduce hormone receptor concentrations which are then involved in the observed Leydig cell dysfunction.