Objective: To investigate the impact of protein kinase B (Akt2) allele deletion on testicular reproductive function, and to discuss the regulatory effect of Cryptotanshinone on the reproductivity of male mice with Akt2 allele deletion and its molecular mechanism.
Methods: Fifteen Akt2 +/+ male mice were randomly divided into Groups A (baseline control, n = 7) and B (stimulation, n = 8), and another 29 Akt2 -/- male mice into C (baseline control, n = 7), D (stimulation, n = 8), E (solvent, n = 7) and F (Cryptotanshinone, n = 7). Groups B and D underwent human chorionic gonadotropin (HCG) stimulation tests at 5 IU / 20 g, while A and C received physiological saline, all for 4 hours; Group F were given gastric lavage of Cryptotanshinone, while E solvent only, at 600 mg/kg twice a day for 8 weeks, both subjected to oral glucose tolerance tests (OGTT) at 2 g/kg before and after the treatment. The body and bilateral testis weights were obtained, the serum testosterone (T) level measured, and the expressions of testicular steroid hormone synthesis and glycometabolism-related genes determined by RT-PCR.
Results: OGTT showed that the level of blood glucose was significantly higher in Groups C and D than in A and B ([10.38 +/- 1.42] and [10.96 +/- 1.81] mmol/L vs [7.92 +/- 0.63] and [8.32 +/- 0.44] mmol/L, P < 0.05), but had no significant differences at different time points in E and F (P > 0.05). The testis weight was remarkably higher in Groups C and D than in A and B ([0.17 +/- 0.01] and [0.17 +/- 0.01] g vs [0.15 +/- 0.01] and [0.15 +/- 0.02] g, P < 0.05), but exhibited no obvious difference in E and F, nor were there any significant differences in body weight among different groups (P > 0.05). The serum T level was markedly higher in Group C than in A ([9.08 +/- 1.59] nmol/L vs [6.42 +/- 0.95] nmol/L, P < 0.05), but evidently lower in F than in E ([5.94 +/- 0.49] nmol/L vs [8.18 +/- 1.44] nmol/L, P < 0.05). The baseline expression levels of Cyp11, Cyp17, 3B-HSD, Star, Gsk3beta, Erk-1, and MCM2 mRNA were significantly higher in Group C than in A (P < 0.05). After HCG stimulation, the expressions of Cyp11, Cyp17, 3B-HSD, and Star mRNA were remarkably increased in B and D, but with no obvious difference between the two groups (P > 0.05), while the expressions of Cyp11, Cyp17, 3B-HSD, Star, Gsk3beta, Erk-1, and MCM2 mRNA markedly decreased in F as compared with E (P < 0.05).
Conclusion: Akt2 gene deletion may affect glycometabolism and testicular function, and cause abnormal glycometabolism and androgen secretion in male mice, whose molecular mechanism is associated with the elevated expressions of the key glycometabolic molecules and of the key enzymes for androgen synthesis. Cryptotanshinone can reduce the levels of androgens by down-regulating the expressions of the key enzymes for androgen synthesis.