Localization of receptor-human chorionic gonadotropin complex to the surface of the luteal and interstitial glandular cells in the pseudopregnant rat ovaries with the peroxidase-antiperoxidase (PAP) complex method

Receptor-bound hCG was localized in pseudopregnant rat ovarian cells at semiultrastructural level with the peroxidase-antiperoxidase (PAP) complex method. The animals received 2, 6, 12 or 24 h prior to killing a single intravenous injection of hCG and the hormone was localized in the 5-micrometer paraffin sections and in the 1-micrometer epon sections using the pre-embedding technique. The peroxidase staining localized to the periphery of the luteal and interstitial glandular cells. No significant staining occurred in the intracellular structures of the cells during the 24-h observation period. However, the appearance of staining in the subplasmalemmal structures can not be excluded. These results are compatible with the previous observations that the receptor-hCG complexes are primarily formed at the surface of the luteal and interstitial glandular cells.     

Photoperiodic modulation of testicular LH receptors in the bank vole (Clethrionomys glareolus)

The temporal changes in testicular binding of 125I-labelled hCG in juvenile bank voles (18 days of age, born and reared in a 18L:6D photoperiod) exposed to a long (18L:6D, Group L) or short (6L:18D, Group S) photoperiod for 0, 3, 7, 14 and 42-56 days were investigated. During testicular maturation, in Group L, there was a slight initial decrease in LH receptor numbers per testis followed by a marked prepubertal rise during the initial phase of rapid testicular growth after which a decrease took place. In Group S, during testicular regression, the temporal changes in LH receptor numbers per testis resembled those of Group L except that the corresponding increase in hCG binding during the initial week was considerably less marked and the receptor numbers remained thereafter at a significantly lower level than in Group L. Leydig cell count indicated that the observed changes in LH receptors per testis were due to changes in the number of Leydig cells as well as in LH receptors per Leydig cell. The present results indicate, that (1) photoperiod is an important modulator of testicular LH receptor numbers in this species, (2) photoperiod or age has no significant effect on the binding affinity of LH receptors, (3) short photoperiods arrest the induction of LH receptors as well as the increase in Leydig cell numbers associated with normal testicular maturation, and (4) changes in LH receptor numbers per testis correlate well with the photoperiod-induced changes in androgen biosynthesis, spermatogenesis and Leydig cell morphology observed in our previous studies.     

Regulation of vascular permeability in rat testes by modified human chorionic gonadotrophin.

High-performance liquid (HPL)-anion-exchange chromatography of testicular interstitial fluid (IF) and medium conditioned by polymorphonuclear leucocytes (PMN) revealed two major peaks (at fractions 2-3 and 7-8), which, with human chorionic gonadotrophin (hCG) increased vasopermeability in rat testes measured by the uptake of iodinated hCG and by interstitial fluid volume. When hCG was incubated with the fraction 7-8 peak and subsequently purified on HPLC it significantly increased testicular vasopermeability with a concomitant accumulation of PMNs in the testicular blood vessels and interstitium. The removal of hCG from the purified preparation with anti-hCG Sepharose 4B abolished the vasopermeability effect of the preparation, confirming that hCG itself is modified in such a way as to produce the response. The results suggest that both IF and PMN-conditioned medium contain two components with different charges, which interact with hCG to increase vasopermeability by a PMN-mediated process. The results also indicated that hCG may itself be modified chemotactically, or so that it elicits production of leucoattractant in the testes.