Search

Objective: To study the impact of the water extract from Codonopsis thalictrifolia Wall (CTW) on the reproductive, Methods: We divided 32 male SD infant rats into four groups of equal number to be treated intragastrical-system of male infant rats. ly with distilled water (control) and CTW at 10 g/kg (low dose) , 20 g/kg (medium dose), and 40 g/kg (high dose), respectively, twice a day for 2 weeks. Then we killed the rats, measured the levels of testosterone (T), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the serum, obtained the testis weight, body weight, testis visceral coefficient and sperm concentration, and detected sperm viability, sperm motility and the level of cyclic adenosine monophosphate (cAMP) in the Leydig cells, followed by, Results: Compared with the control group, the low-dose, me-analysis of differences among different groups using the SPSS software. Medium-dose and high-dose CTW groups showed significant decreases in the serum T level ([3.09 +/-0.42] vs [1.22 +/-0. 32] , [1.06 +/- 0.29] and [0.57 +/-0.18] nmol/L, P<0.01), testis weight ([1.40 +/-0.16] vs [0.96 +/-0.09], [0.92 +/-0.11] and [0.91 +/- 0.08] g, P <0.01), and sperm concentration ([1.03 +/-0.16] vs [0.19 +/-0.07], [0.17 +/-0.08] and [0.16 +/-0.07] x 10(6)/ml, P <0.01), but a dramatic elevation in the testis visceral coefficient ([42.22 +/- 3.02] vs [51.39 +/- 3.09], [52.28 +/- 4.86] and [54.13 +/-6.06] mg/10 g, P <0.01); the medium- and high-dose CTW groups exhibited remarkable increases in the levels of serum LH ([13.62+/-0.89] vs [14.69 +/-0.12] and [14.93 +/-0.28] ng/L, P<0.01) and FSH ([4.32 +/-0.18] vs [4.77 +/-0.23] and [4.89 +/-0. 38] IU/L, P <0.05); all the three CTW groups showed markedly inhibited serum T secretion ([1.85 +/- 0.18] vs [1.42 +/-0.15], [1.12+/-0.18] and [0.88 +/-0.21] nmol/L, P<0.01) and intracellular cAMP ([5.51 +/-0.12] vs [4.39+/-0.06], [4.28 +/-0.07] and [4.11 +/- 0.10] nmol/L, P <0.01) in the Leydig cells., Conclusion: The water extract from CTW may reduce the synthesis of testosterone in the serum of male infant rats through the PKA pathway and consequently inhibit their testicular development and sperm production and affect the development of their reproductive system.

Stimulated by retinoic acid gene 8 (STRA8) is specifically expressed in mammalian germ cells before their transition from mitosis to meiosis. STRA8 expression is observed only in the postnatal testis. Single nucleotide polymorphisms but no mutations were identified in the coding or proximal promoter region of STRA8 in some gonadal dysgenesis patients. Studies on the teratocarcinoma cells and embryonic stem cells (ESC) transfected with STRA8-EGFP, a fusion construct harboring the promoter and coding region of the enhanced green fluorescence protein, have shown that the STRA8-EGFP positive cells may undergo meiosis, develop into sperm and generate live offspring mice. STRA8-EGFP positive cells derived from the bone marrow are able to differentiate into spermatogenic cells, but arrest in the premeiotic stage, and those from the adult mouse testis, when cultured in ESC culture conditions, may acquire ESC properties, pluripotency and redifferentiation capacity and act as a new stem cell source for tissue regeneration. The presence of oocytes renewed in postnatal mouse ovaries calls in question the absence of STRA8 in postnatal mouse ovaries.

Stra8 (stimulated by retinoic acid gene 8) is a specific expression gene in mammalian germ cells' transition from mitosis to meiosis. Stra8 expresses in an anterior to posterior wave from embryonic days 12.5 to 16.5 in germ cells of XX gonads in mice. Meiosis germ cells are observed 1 day after Stra8 expression, which begins in the testis after birth and triggers meiosis entry. Germ cell sex determination is directed by a difference in the timing of entry into meiosis in embryonic gonads. The position of retinoic acid production and CYP26b1 expression that metabolizes RA to an inactive form regulates Stra8 expression. Although cytoplasmic protein Stra8 is necessary for the entry of germ cells into meiotic prophase, the function of the protein remains unknown.

This article reviews the specific expression of many proto-oncogenes during male germ cell development. The normal expression of proto-oncogenes plays an important role in the regulation of spermatogonial mitosis, spermatocyte meiosis as well as spermiogenesis and sperm maturation.

Apoptosis is necessary for the development and maturation of Leydig cells. However, increased apoptosis results the decline of testosterone production, which may increase germ cell apoptosis and the possibility of infertility. There are several aspects contributing to Leydig cell apoptosis such as ethane dimethanesulphonate (EDS), glucocorticoid, developmental stage and some hormones including FSH, LH/hCG and testosterone. A number of genes are involved in the regulation of Leydig cells apoptosis. It was reported that SCF/c-kit, Bcl-2 and Bcl-xl inhibited the apoptosis while caspase-3, Fas, Bax and clusterine stimulated it.

In recent years, people have paid more attention to the spermatogonial stem cells that have the capacity for self renewal and multilineage differentiation and produce daughter cells that can expand and differentiate into spermatozoa under the adjustment of self genes and external signal. This article reviews recent advances in studies of enrichment and original selection of the spermatogonial stem cells. This review also summarizes some control factors in proliferation and transplantation techniques.