Sea cucumber peptides positively regulate sexual hormones in male mice with acute exhaustive swimming: possibly through the Ca2+/PKA signaling pathway

Sea cucumber peptides (SCPs) have been proven to have many active functions; however, their impact on testosterone synthesis and the corresponding mechanism are not yet clear. This study attempts to explore the effects of SCPs on sex hormone regulation in acute exhaustive swimming (AES) male mice and the possible mechanisms. In the present study, SCP intervention significantly prolonged exhaustive swimming time and reduced exercise metabolite accumulation. The reproductive ability-related parameters including penile index, mating ability, testicular morphology, and sperm storage were dramatically improved by SCP intervention. Notably, SCPs markedly reversed the AES-induced decrease in serum testosterone (T), estradiol (E2), and follicle-stimulating hormone (FSH) levels. Moreover, treatment with a high dose of SCP (0.6 mg per g bw) significantly enhanced the expression of testosterone synthesis-related proteins in testis, meanwhile markedly increasing the gene expression of StAR, Hsd17b3, Hsd17b2, Ldlr, and Cyp19a1. Serum metabolomics results indicated that SCP intervention notably upregulated the expression of 1-stearoyl-2-arachidonoyl-sn-glycerol but downregulated the concentrations of succinate and DL-lactate. Furthermore, serum metabolomics combined with testicular transcriptome, western blot, and correlation analyses demonstrated that SCPs may regulate testosterone synthesis via the Ca2+/PKA signaling pathway. This study indicated that the SCP could be a potential dietary supplement to improve the symptoms of decreased sex hormones related to exercise fatigue.