OBJECTIVETo study the regulatory effect of Bushenfang on the serum testosterone (T) level of naturally aging rats and its mechanism, in order to provide a theoretical and experimental basis for the clinical treatment of late onset hypogonadism (LOH) in males.

METHODSThirty-two 18-month-old male SD rats were randomly divided into four groups of equal number, naturally aging model and low-, medium- and high-dose Bushenfang groups, and another eight 4-month-old rats were taken as normal controls. The rats of the aging model and normal control groups were treated with normal saline, while those of the low-, medium- and high-dose Bushenfang groups received intragastrically Bushenfang at 3.25, 7.50 and 15.00 g/kg, respectively, all for 3 weeks. Then the rats were sacrificed, the histomorphologic changes of the testis observed by HE staining, the serum T level measured by radioimmunoassay, and the expressions of the StAR protein, P450scc and 3beta-HSD I determined by RT-PCR.

RESULTSThe number of Leydig cells was obviously increased after Bushenfang treatment. The levels of serum T were significantly higher in the low-, medium- and high-dose Bushenfang groups ([6.74 +/- 1.56] nmol/L, [8.50 +/- 1.99] nmol/L and [12.41 +/- 2.91] nmol/L) than in the model group ([3.48 +/- 0.75] nmol/L) (P < 0.05). The three Bushenfang groups also showed a remarkable elevation in the mRNA expressions of StAR (0.74 +/- 0.29, 0.83 +/- 0.32 and 1.35 +/- 0.50), P450scc (0.72 +/- 0.36, 1.023 +/- 0.30 and 1.41 +/- 0.37) and 3beta-HSD I (0.58 +/- 0.14, 0.72 +/- 0.07 and 0.85 +/- 0.18), as compared with the models (StAR: 0.44 +/- 0.09; P450scc: 0.33 +/- 0.05; 3beta-HSD I: 0.34 +/- 0.02), with significant differences in the StAR expression between the high-dose Bushenfang and the model groups, as well as in P450scc and 3beta-HSD I expressions between the medium- and high-dose Bushenfang and the model groups (P < 0.05).

CONCLUSIONBushenfang could improve the pathological status of testicular injury and increase the expression of testosterone synthetase, which might be the mechanism behind its regulatory effect on the serum T level of aging rats.