Effects of estrogen, SU-9055, and cyproterone acetate on the hypersecretory activity in the seminal vesicles of the castrate catfish, Heteropneustes fossilis (Bloch)

Survey of the Adrenal Homolog in Teleosts

The adrenal homolog of teleosts is not a compact organ as the adrenal glands of most vertebrates but is composed by aminergic chromaffin and interrenal steroidogenic cells located mostly inside the head kidney that, in this taxon, generally has a hematopoietic function. The two tissues can be mixed, adjacent, or completely separated and line the endothelium of the venous vessels or are located in close proximity. The chromaffin cells in some species are also present in the posterior kidney. Histological and ultrastructural work revealed cytological peculiarities of both types of cells as compared to those of other vertebrate species. In particular, the interrenal ones can show some variations in ultrastructure depending on sex, time of the year, and relation to stress events. A periodic renewal of the whole gland tissue is also sustained by some studies. Research regarding development is scanty as compared to mammals and most studies go back to the early years of the past century. The adrenal homolog of teleosts is under hormonal and neuronal control. Moreover, local paracrine interactions may play an important role in modulating a system involved in stress response and osmoregulation. Most previous studies involved a few species with the object of intensive rearing for commercial purposes; in fact cortisol, the main hormone secreted by the interrenal cells, can also influence reproduction and growth. This review summarizes data from morphocytological work and refers to other excellent reviews regarding physiology. Some of the results are compared to data available from other fishes and vertebrate classes with the aim of including them in an evolutionary and environmental framework.

Castration-induced hyperactivity of seminal vesicle in the catfish Clarias batrachus: a case of paradox and blockade by antiandrogen (cyproterone acetate) treatment

Castration of the catfish Clarias batrachus in late preparatory-early prespawning phase (April-May) caused time-dependent stimulatory effect on morphology, weight, and in the concentrations of biochemical correlates, such as total proteins, fructose, hexosamines and sialic acid in the seminal vesicle (SV). The peak changes were noticed on week 4 of castration. The hyperactivity was related to augmented production of testosterone by the SV of castrates with the levels significantly high from week 3 onwards. As a result, serum testosterone level fluctuated with a significant decrease in the first and fifth weeks, a significant increase in the third week, and no significant difference in the second and fourth weeks. Serum E2 level decreased significantly throughout. Cyproterone acetate treatment (CA; 1 mg/fish daily for 21 days) from the second day of castration decreased the size and weight of the SV and the concentrations of total proteins, hexosamines, fructose and sialic acid. The antiandrogen treatment did not alter serum testosterone level but the E2 level was significantly decreased. It is concluded that the hypersecretory activity of the SV in castrates is a sequel to local synthesis and action of testosterone and the effect could be prevented by CA by blocking androgen actions.

Annual cyclic, and castration and cyproterone acetate-induced, changes in sialic acid content of the seminal vesicle of the catfish, Heteropneustes fossilis (Bloch)

In this study, the presence of sialic acid is demonstrated in the seminal vesicle (SV) of Heteropneustes fossilis. Sialic acid levels show an annual variation that was correlated with the secretory activity of the SV (expressed as the SV somatic index (SV-SI)) with the index being lowest in resting phase (January) and highest in spawning phase (July). Sialic acid was not detectable from November to March (resting to mid-preparatory phases). Castration (3 weeks) induced a significant rise in both SV-SI and SV sialic acid content possibly due to an elevated local production of androgens under the influence of increased gonadotropin secretion. Cyproterone acetate treatment caused a significant decrease in both SV-SI and SV sialic acid content. The results suggest that secretion of sialic acid in the SV is influenced by androgens and its measurement can be used as a simple and reliable index for quantitative assessment of the functional testicular state.

Effects of natural androgens and corticosteroids on gonad differentiation in the rainbow trout, Salmo gairdneri

Rainbow trout fry were treated with equimolar quantities of cortisol, cortisone, androstenedione, and 11 beta-hydroxyandrostenedione, added to the aquarium water during a 4-week period. All four steroids inhibited ovarian growth. Androstenedione did not influence gonadal sex differentiation; the other steroids pushed the sex ratio in the male direction. However, a near to normal sex ratio was observed 300 days after the 11 beta-hydroxyandrostenedione treatment. When added to the food in two different doses during 8 weeks, 11 beta-hydroxyandrostenedione had a pronounced masculinizing effect, and androstenedione did not modify the gonads at all. It is suggested that the two exogenous corticosteroids were probably converted into 11-oxygenated androstenedione derivatives, and that these 11-oxygenated androstenedione derivatives are particularly important in sustaining the differentiation and early development of the testes in rainbow trout. Testosterone does not seem to be indispensable for these processes, because two different doses of testosterone-blocking cyproterone acetate, added to the food for 8 weeks, failed to affect early gonad development.

Effects of an antiandrogen, cyproterone acetate, on the kidney of the three-spined stickleback (Gasterosteus aculeatus L.)

The fine structure of the kidney is studied in the sexually mature male three-spined stickleback after administration of an antiandrogen, cyproterone acetate. Under these conditions, the dedifferentiation of renal tubules is characterized by the same involutive processes as those induced by castration, with the difference that cyproterone acetate only begins to act after 14 days whereas after castration the first signs of involution are visible after 7 days. The ultrastructural modifications affect the nucleoli, the rough endoplasmic reticulum and the Golgi apparatus. They reflect an inhibition of the secretory process. The results obtained demonstrate that administration of cyproterone acetate to male sticklebacks has an inhibitory effect on renal target cells, apparently indistinguishable from the changes induced by lack of male sex hormone, and that this drug may be a valid substitute for castration in fish.