The biosynthesis of steroid glucuronides in the testis of the zebrafish, Brachydanio rerio, and their pheromonal function as ovulation inducers

Abstract

In female zebrafish ovulation could be induced by male holding water, testis homogenates, and testis fractions containing steroid glucuronides. Deglucuronidation of these fractions led to a loss of ovulation-inducing potency, indicating steroid giucuronides as ovulation inducers. The chemical substances were perceived by the recipient females by means of olfaction. Incubation experiments showed the capacity of the testes to synthesize various C,, and C,, steroids and seven different steroid glucuronides, i.e., 17ct,20P-dihydroxy-4-pregnen-3-one-, testosterone-, androsterone-, epiandrosterone-, 5u-androstane-3a,17@diol-, and 5a-androstane-3l3,17P-diol glucuronide. GC-MS analysis showed the presence of glucuronides of 5a-androstane-3a,l7@dioland cholesterol in male holding water, the latter probably originating from the liver. These compounds may be among the steroid glucuronides functioning as ovulation-inducing pheromones. 0 1987 Academic Press. Inc.

?Classical? and ?non-classical? reproductive steroids in fish

“…5fl-Metabolites of C19 or C21 precursors predominated in testicular and seminal vesicles incubations, and in seminal fluid of Clarias gariepinus (Schoonen et al, , 1988a, and in testicular incubations of Rhabdosargus sarba (Yeung and Chan, 1985) and Gobiusjozo . 5a-Reduction predominates in Glossogobius olivaceus (Gobiidae) (Asahina et aL, 1985) and Brachydanio rerio (Van den Hurk et al, 1987). In the ambisexual species Coris julis (Labridae) and Pagellus acarne, 5fl-reduction predominated in males and 5 a-reduction in females (Reinboth and Becker, 1984;Reinboth et al, 1986).…”

Functional characterization and expression analysis of the androgen receptor in zebrafish (Danio rerio) testis

“…Except for a study on the production of steroid glucuronides and their possible role as pheromones (Van den Hurk et al 1987), no information has been published on the identity of the main androgenic steroids produced by adult zebrafish testis tissue. To address this caveat, the following experiment was performed in triplicate: testis tissue was collected from eight adult males (28.7G3.6 mg total wet weight).…”

Multiplicity of UDP-glucuronosyltransferases in fish. Purification and characterization of a phenol UDP-glucuronosyltransferase from the liver of a marine teleost, Pleuronectes platessa

“…In common with avians, fish also have nucleated red blood cells, resulting in lower turnover rates of haem; thus the capacity for bilirubin glucuronidation may be lower. Biliary excretion of androgen and oestrogen glucuronides has been reported in a number of fish species [6,34]; however, glucuronidation of steroids may be quantitatively more important in reproductive tissue of fish, where relatively high levels of steroid glucuronides have been measured (reviewed in [11] Multiple UDPGT activities were partially resolved by ionexchange chromatography, and, after affinity chromatography of these co-purified activities, a major polypeptide of subunit molecular mass 55 kDa was present on SDS/PAGE. At least five other polypeptides with molecular masses of 52-57 kDa were also identified, and appeared more abundant in preparations displaying relative enrichments of bilirubin and testosterone UDPGT activities.…”

“…Glucuronidation of endogenous compounds is important in fish species for chemical signalling (dihydroprogesterone glucuronides are the sex pheromones [5][6][7]), cessation of hormone action via excretion (steroid and thyroid hormones [8,9]) and in biliary elimination of bilirubin [10]. Glucuronide conjugates of a wide range of structurally diverse xenobiotic compounds have also been detected in bile, urine and tissues in fish, thus demonstrating the importance of glucuronidation in their detoxication and elimination (recently reviewed in [11]).…”