Effect of Injected Human Chorionic Gonadotrophin on Capillary Permeability, Extracellular Fluid Volume and the Flow of Lymph and Blood in the Testes of Rats

Abstract

The subcutaneous injection of human chorionic gonadotrophin (HCG) into adult male rats caused appreciable rises in capillary permeability and lymph flow in the testis, accompanied by smaller rises in the volume of extratubular, extracellular fluid. Most of these changes were already apparent 8 h after injection, but became progressively greater during the next 12 h. Testicular blood flow was unchanged at 12 h but increased slightly between 12 and 6 h after injection. The primary effect is probably the increase in capillary permeability. The timing of these changes suggests that HCG does not affect the capillaries directly, but it would seem that the changes are due to some substances secreted by the testis in response to the HCG. It is clear that these changes will have important influences both on the access to the testicular cells of peptide hormones in the blood and also on the passage into the venous blood of hormones secreted by the testis.

Orally applied doxazosin disturbed testosterone homeostasis and changed the transcriptional profile of steroidogenic machinery, cAMP/cGMP signalling and adrenergic receptors in Leydig cells of adult rats

“…The mechanisms controlling vasomotion are complex and incompletely resolved, but in the rat testis, it is known that vasomotion is testosterone-dependent, is not seen prior to puberty, and is responsive to catecholamines whether peripherally infused, or microperfused around restricted fields of the testicular microvasculature (for references please see Damber et al, 1987;. The numerous papers (Sharpe, 1979(Sharpe, , 1980(Sharpe, , 1981(Sharpe, , 1984Setchell & Sharpe, 1981;Sharpe & Cooper, 1983;Bergh et al, 1986;Veijola & Rajaneimi, 1986;Widmark et al, 1989) showed that measurement of the volume of TIF, the rate of its formation (i.e. capillary permeability) and clearance is a valid parameter of testicular vasculature, because not only this controls the rate of transport of LH and other compound to the Leydig cells but it may also affect the concentration of testosterone in TIF by altering the volume of fluid into which the androgen is secreted.…”

“…The collection of TIF is of considerable potential value, both as an indicator of changes in capillary wall permeability (i.e. by measurement of interstitial fluid volume) and as a means of assessing changes in the interstitial hormonal environment of the testis (Setchell & Sharpe, 1981). The gonadotropins cause large increase in the volume of interstitial fluid within the testis (Sharpe, 1979(Sharpe, , 1980(Sharpe, , 1981(Sharpe, , 1984, because of an increased permeability of testicular capillaries (Sharpe & Cooper, 1983).…”

The Movement of Fluids and Substances in the Testis

“…It has also been found that the albumin space at equilibrium in the rat testis is approximately equal to the Cr-EDTA space of between 100 and 120 f{l/g (Setchell and Sharpe 1981), and the use of albumin has certain practical advantages, although the time required for equilibration is considerably longer (6 h compared with less than 30 min for Cr-EDTA). There is also recent microscopic evidence that albumin is distributed throughout the interstitial tissue, and does not enter the Leydig cells; it does appear to be taken up to some extent by macrophages in the interstitial tissue (Christensen et al 1985), and this may explain the somewhat higher values for albumin spaces found in normal rat testes 24 h after injection of the marker (Set chell and Wallace 1972).…”

Limitations Imposed by Testicular Blood Flow on the Function of Leydig Cells in Rats in vivo

“…Further studies are needed in which extracellular interstitial and tubule fluids are evaluated separately. Other studies have shown that the blood vessels in the aspermatogenic testes increase their permeability to albumin after treatment with hCG (Galil and Setchell1983;Wang et al 1983) as in normal testes (Setchell and Sharpe 1981).…”