C-type natriuretic peptide (CNP) is an important local regulator of long bone growth. It catalyzes the synthesis of cGMP after binding to its receptor natriuretic peptide receptor-B (NPR-B) ,and regulates long bone growth by activating downstream factors. Though the mechanism of the regulation of CNP signaling remains unclear, it has been demonstrated that CNP signaling has a "cross-talk" with the fibroblast growth factor receptor 3 pathway in cartilate.Heterozygous NPR-B mutations maybe one of the molecular basis of idiopathic short stature. CNP can be used as a biological marker of linear growth, with great importance in growth monitoring, diagnosis and treatment of growth disorders.The research on the mechanism of CNP signaling system in endochondral ossification will contribute to a new medication for bone development disorders in the future.

Objective To evaluate the long-term final adult height outcome of combined treatment with gonadotropin-releasing hormone analogue(GnRHa)and recombinant human growth hormone(rhGH)in girls with idiopathic central precocious puberty(ICPP).Methods Out of 49 sirls with ICPP[treated with GnRHa at a dose of 60-80 μg/kg every 4 weeks for at least 6 months,whose height velocity fell below 4 cm/year and showed no improvement of predicted adult height(PAH)in 6 months],26 received(rhGH-combined group),in addition to chronological age,and duration of GnRHa treatment,who showed the same growth pattern but refused rhGH treatment,served to evaluate the efficacy of rhGH in addition.At the conclusion of the smdy,all the girls had been followed up for(3.3±1.9)years,and(3.2±0.9)years in rhGH-combined group and control group,respectively;and had achieved adult heisht.To compare the PAH with the final adult height(FAH)before and after treatment in the two groups.Results During rhGH treatment, height velocity of the rhGH-combined girls increased significantly[(6.7±2.0 vs <4)cm/year baseline],RhGH-combined gids showed an adult height far higher than pretreatment PAH [(157.5±4.5 vs 148.1±4.6)cm,P<0.01],and target height[(154.4±4.6)cm] was,significantly excceded.The control group reached an adult heisht also significandy higher than pretreatment PAH[(154.7±5.5vs 150.3±6.0)cm,P<0.01],while target height[(155.6±4.3)cm]was just reached but not significantlyexcceded.The gain in height obtained,calculated between pretreatment PAH and final heisat,(9.4±4.9)cm in rhGH-combined group was much more than that(4.3±4.2)cm in the control group(P<0.01).Conclusion RhGH may accelerate the linear growth and improve adult height of GnRHa-treated ICPP girls.

Objective To observe the final adult height of 20 boys with idiopathic central precocious puberty (ICPP) treated with slow-releasing gonadotropin-releasing hormone analogue(GnRHa).Methods Twenty boys with ICPP were treated with GnRHa for( 20.0 ± 6.1 ) months.At the beginning of therapy,mean chronological age and bone age was( 11.4 ± 1.0 ) years and ( 13.0 ± 0.4 ) years,respectively,GnRHa was discontinued when the boys reached the chronological age and bone age of( 13.2 ± 1.1 ) years and ( 13.7 ± 0.6 ) years,respectively.After the end of treatment,all the boys had been followed up for( 3.3 ± 1.5 ) years and had achieved adult height.Comparisons were made among their predicted adult height ( PAH ),final adult height ( FAH ),and target height ( THt ).The long-term outcome of final adult height in boys with ICPP was investigated after GnRHa treatment.Results All the boys reached target height range.Final height was similar to the target height [ ( 169.8 ± 5.8 vs 167.8 ± 4.6 ) cm,P＞0.05 ].The height gain,defined as the difference between predicted adult height at the start of treatment using the height SDS for bone age and actual adult height was( 3.62 ± 3.57 ) cm with the residual growth capacity of ( 11.82 ±3.99)cm,PAH significantly improved after GnRHa treatment compared with before treatment [ ( 169.0 ± 5.0 vs166.2 ± 4.2 ) cm,P＜0.01 ].There were no differences among PAH,FAH,and THt.Conclusion GnRHa treatment improves final height within the range of target height in boys with central precocious puberty.

OBJECTIVETo investigate the effect of estrogen on cell proliferation and expression of proteins of C-type natriuretic peptide (CNP), natriuretic peptides B receptor (NPR-B) and natriuretic peptides C receptor (NPR-C) in ATDC5 cells during chondrogenesis.

METHODATDC5 cells were induced for differentiation with insulin 10 µg/ml (day 0), and were started to be investigated on day 6. They were incubated with: (1) Estradiol (E2) at different concentrations (10(-11)-10(-5) mol/L) for 24 hours (for studying cell proliferation), or for 48 hours (for studying CNP, NPR-B and NPR-C protein expression); (2) E2 (10(-8) mol/L) for 24, 48, 72, 96 and 120 h (for studying cell proliferation), or for 24, 48, 72 and 96 hours (for studying CNP, NPR-B and NPR-C protein expression); (3) E2 (10(-8) mol/L) , and/or ICI 182782 (estrogen receptor antagonist ) (10(-7) mol/L) for 24 hours (for studying cell proliferation). ATDC5 cells proliferation were determined by MTT (OD value). Western-blotting was performed to identify the protein levels of CNP, NPR-B and NPR-C.

RESULT(1) After incubation with E2 (10(-11)-10(-5) mol/L) for 24 h, ATD5 cell number increased with the increasing E2 concentration, peak in E2 concentrations of 10(-9) and 10(-8) mol/L (0.56 ± 0.06 and 0.52 ± 0.02, P < 0.05 and <0.01, respectively) , while significantly decreased in E2 (10(-5) mol/L) (0.30 ± 0.02) compared with DMSO-control (0.38 ± 0.02) (P < 0.05). After incubation with E2 (10(-11)-10(-5) mol/L) for 48 h, the protein level of CNP, NPR-B and NPR-C increased significantly, with the greatest effect seen at a concentration of 10(-10) mol/L E2 for CNP and NPR-B, 10(-9) mol/L E2 for NPR-C (P < 0.05). (2) After incubation with E2 (10(-8) mol/L) for 24 to 96 hours: (1) The cell number in each of the four time points was significantly increased compared with DMSO-control, with the greatest effect in 48 h (0.030 ± 0.003) (P < 0.05 or <0.01, respectively). While the cell number at 120 h was similar to that in DMSO-control. (2) The protein level of CNP increased significantly at 24 h (P < 0.05), seemed to be increased at 48 h and 72 h and decreased at 96 h. Both NPR-B and NPR-C level seemed to be increased at 24 h (P = 0.060 and 0.055, respectively) and seemed to decrease at 48 h, with decreasing significantly at both 72 h and 96 h (P < 0.05). (3) After incubation for 24 h, there was significant difference among the cell number of the four groups (P < 0.05). Cell number of group E2 (0.470 ± 0.032) was increased compared with group (E2+ICI) (0.410 ± 0.018), both being increased compared with group DMSO-control (0.370 ± 0.011, P < 0.05, respectively). There was no difference in cell number between group ICI 182782(0.360 ± 0.035) and group DMSO-control.

CONCLUSIONE2 promotes the proliferation of ATDC5 cells i.e. chondrogenesis via estrogen receptor mediated mechanism, in both concentration-dependent and time-dependent manner. E2 (10(-11)-10(-8) mol/L) up-regulates protein expression of CNP, NPR-B and NPR-C of ATDC5 cells during chondrogenesis, and regulate the expression of the three proteins mentioned above positively or negatively at different time point, which implied that estrogen is one of the regulators of CNP signaling pathway.

Animals ; Blotting, Western ; Cell Differentiation ; drug effects ; Cell Line ; Cell Proliferation ; drug effects ; Chondrogenesis ; Dose-Response Relationship, Drug ; Estradiol ; pharmacology ; Gene Expression Regulation ; drug effects ; Mice ; Natriuretic Peptide, C-Type ; metabolism ; Receptors, Atrial Natriuretic Factor ; metabolism ; Signal Transduction ; drug effects ; Time Factors