The role of C-type natriuretic peptide in rat testes during spermatogenesis

C-type natriuretic peptide （CNP） is a 22-amino acid peptide and act as a local paracrine or autocrine regulator. There is growing evidence that ChIP is involved in male reproductive processes. To investigate the role of CNPduring spermatogenesis, we measured the mRNA expression of CNPand its specific membrane-bound natriuretic peptide receptor-B （NPR-B） using real-time RT-PCR in the testes of normal rats on different postnatal days. After that spermatogenesis dysfunction model induced by ornidazole was established with the aim to study the correlation of CNPwith spermatogenic dysfunction. Then, Sertoli cells from 18- to 22-day-old healthy male rats were cultured in the presence of different CNPconcentrations （1 ×10-6, 1×10-7 and1×10-8 mol l-1）, and the mRNA expression levels of androgen.binding protein, inhibin B and transferrin were examined at 0 min, 30 min, 1 h, 2 h, 4 h, 8 h, 12 h, 24 h and 48 h. During the postnatal development of rat testes, the highest mRNA expression levels of CNPand NPR-B were found at postnatal Do, and the levels then declined gradually, with a second ChIPpeak at postnatal D35. In the ornidazole-induced infertile rat testes, CIVPgene expression was lower than in the uninduced rats （P〈0.05）, while IVPR-Bgene expression was greater （P〈0.05）. In cultured Sertoli cells, supplementation with CNP stimulated the gene expression of androgen-binding pmteirginhibin B/transferrin, particularly at 12 h, and 1× 10-7 mol l-1 CNP had the highest upregulation effect. The gene expression levels of CNPIIVPR-B in rat testes at different postnatal stages and in infertile rat testes indicated that CNP may participate in the physiology and/or pathology related to spermatogenesis. Moreover, ChIP regulated endocrine function in Sertoli cells. Taken together, these results showed that CNP is closely tied to spermatogenesis.

Regulation of C-type Natriuretic Peptides and Natriuretic Peptide Receptor-B Expression in Diabetic Rats Renal Treated by Tongluo Recipe(通络方)

To investigate the expression of C-type natriuretic peptides （CNP） and natriuretic peptide receptor-B （NPR-B） receptor in diabetic rats renal cortex, and the regulation by Tongluo Recipe （通络方, TLR）. Methods： Sixty male SD rats were divided into 3 groups： the normal control group, diabetic model group and diabetic TLR group. Each group was further divided into two subgroups of ten in each, according to 4-week or 12-week observation period. Streptozotocin （STZ）-induced diabetic rats were treated with TLR （1.0 g.kgl＇d1） for 4 and 12 weeks, respectively. （1） The essential information was collected for comparing renal mass, serum creatinine and 24 h urine albumen on each group was calculated. （2） CNP mRNA and NPR-B mRNA were detected by realtime-polymerase chain reaction （PCR） on rats renal cortex. （3） Concentration of CNP on renal cortex or serum were analyzed by enzyme-linked immunosorbent assay （ELISA）. （4） Pathological evaluation and NPR-B immunostaining for renal tissue were also performed. Results： （1） CNP and NPR-B mRNA levels were detected in each treated or untreated group, with slight elevated in untreated diabetes rats administrated with STZ after 4-week and CNP mRNA level remarkable elevated at 39.21 times higher than normal control group after 12 weeks, but NPR-B mRNA level showed a remarkably down-regulation at 98.07% after 12 weeks. CNP mRNA of TLR-treated group was also elevated after 12-week treatment, but less than untreated group. （2） Concentrations of CNP in renal cortex were obviously increased in treated or untreated diabetes rats, within these groups the treatment of TLR was found more significantly on prompting CNP concentration. Comparing to normal group, serum concentrations of CNP were also increased in treated or untreated diabetic groups, but there was no difference between these diabetic groups. （3） Renal lesions like glomerular volume increased are observed mostly in the relative eady stage after 4 weeks. Although TLR treated group had no significant difference in their glomerular volume, the degrees of injury of glomerulus were ameliorated, as well as the NPR-B immunostaining enhanced in glomerulus. Weakly positive immunostaining of NPR-B are observed in glomerulus of normal control, and negative in glomerulus of untreated diabetes rats administrated with STZ after 12 weeks, whereas TLR-treatment groups showed a little enhancement. Conclusion： CNP and NPR-B showed different characteristic on renal cortex at different pathological period in diabetes rats, and TLR regulated their expression.

Role of C-type natriuretic peptide in the function of normal human sperm

C-type natriuretic peptide （CNP） is a newly discovered type of local regulatory factor that mediates its biological effects through the specific, membrane-bound natriuretic peptide receptor-B （NPR-B）. Recent studies have established that CNP is closely related to male reproductive function. The aims of this study were to determine the distribution of CNP/NPR-B in human ejaculated spermatozoa through different methods （such as immunolocalization, real time polymerase chain reaction and Western Blot）, and then to evaluate the influence of CNP on sperm function in vitro, such as motility and acrosome reaction. Human semen samples were collected from consenting donors who met the criteria of the World Health Organization for normozoospermia. Our results show that the specific receptor NPR-B of CNP is localized in the acrosomal region of the head and the membrane of the front-end tail of the sperm, and there is no signal of CNP in human sperm. Compared with the control, CNP can induce a significant dose-dependent increase in spermatozoa motility and acrosome reaction. In summary, CNP/NPR-B can affect sperm motility and acrosome reaction, thus regulating the reproductive function of males. CNP may be a new key factor in regulating sperm function.