Pyriproxyfen Disrupts the Ongoing Spermatogenesis Wave in Danio rerio Potentially Mediated by Voltage-Dependent Calcium Channels and Protein Kinase C.

Pyriproxyfen (PPX) is an analog of the juvenile hormone from insects. Following our previous studies, for the ex vivo short-term effect, we chose 10-9 M pyriproxyfen to analyze the morphology of spermatogenesis wave cells. In silico docking and ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity) studies were carried out to preliminarily predict possible interaction modes between PPX and the T-type voltage-dependent calcium channel (T-VDCC), as well as with protein kinase C (PKC), as we previously reported by using pharmacological approach. The in silico ADMET evaluations revealed that PPX demonstrates notable lipophilicity. Moreover, PPX is predicted to inhibit the enzymatic activity of CYP1A2, CYP2C19, CYP2C9, and CYP2D6. Furthermore, in silico molecular docking analyses revealed that PPX has the potential to interact with the T-VDCC through hydrogen bonds with Gln1653 and hydrophobic interactions with Leu291, Phe322, Phe1607, and Leu1656. Possible interactions of PPX with PKC involve ionic bonding with Lys463, hydrogen bonds with His592, and hydrophobic interactions with Lys463, Val596, Gly591, Phe593, Lys611, Asp711, and Leu714 reinforcing these both targets to PPX. In summary, short-term PPX exposure influenced the morphology of testicular cells (spermatids, spermatozoa, and Leydig cells) through interactions with molecular targets. Findings reveal the bimodal effects (on morphology and signaling) of this compound on specific cells within the spermatogenic wave, endocrine cells, and signal transduction proteins. This interference may impair reproduction and lead to male infertility. In addition, the prediction from both molecular docking and ADMET supported our in vitro mechanistic analysis firstly reported in the testis of Danio rerio.