Effect of tankyrase 1 on autophagy in the corpus cavernosum smooth muscle cells from ageing rats with erectile dysfunction and its potential mechanism

This study compared tankyrase 1 expression and autophagy quantity between erectile dysfunction （ED） and non-ED rats＇ corpus cavernosum smooth muscle cells （CSMCs）. This study aslo explored the effect and possible mechanism of tankyrase 1 on autophagy and cell proliferation in ageing ED rats＇ CSMCs. The intracavernous pres- sure and mean systemic arterial pressure were measured to investigate erectile function so that eight 24-month-old ED and eight 8-month-old male Wistar rats were choosed respectively. The rat CSMCs were isolated and cultured by enzyme digestion, in which tankyrase 1 expression and autophagy quantity were compared. Tankyrase 1 over-expression was induced with plasmid transfection by Lipofectamine^TM. The effect of tankyrase 1 overexpression on proliferation, autophagy and mTOR pathway in 24-month-old ED rats＇ CSMCs was measured by the cell growth curve in MTT assay, cell cycle analysis in flow cytometry （FCM）, key protein expression in Western blot, autophagy quantity in transmission electron microscopy, monodansylcadaverine staining and GFP-LC3 fluorescence. The primary CSMCs were confirmed by immunofluorescence, and the purity was 99.1% in FCM. Compared with that of 8-month-old rats, tankyrase 1 expression and autophagy quantity significantly decreased in 24-month-old ED rats＇ primary CSMCs （P 〈 0.01）. Tankyrase 1 overexpression significantly increased the growth rate （P 〈 0.05） and increased the S phase of cell cycle （P 〈 0.01）. The autophagosome quantity was remarkably increased （P 〈 0.01）, LC3-Ⅰ/Ⅱ and Beclin 1 were upregulated （P 〈 0.01 and P 〈 0.05）, and p-p70S6K （Thr389） was downregulated in 24-month-old ED rat CSMCs （P 〈 0.05）. In conclusion, Tankyrase 1 and autophagy decrease in the CSMCs from aging rats with ED, and tankyrase 1 may have a positive effect on proliferation by enhancing autophagy and regulating the mTOR signalling pathway.

Effects of chronic renal failure on the expression of connexin 43 in the rat＇s corpus cavernosum

Aim： To explore the mechanism of chronic renal failure （CRF）-related erectile dysfunction （ED）. Methods： CRF experimental models were established by 5/6 nephrectomy from male Sprague-Dawley rats. Both the rats from the control group （NCRF group, n = 6） and the experimental group （CRF group, n = 30） were injected with a low dose （80 μg/g） of apomorphine in the 12th week after resection surgery to measure corresponding penile erections. Western blot method was thereafter conducted to measure the expression of connexin 43 （CX43） in the rat corpus cavernosum in the 12th week after the resection surgery. Results： There was one death in the NCRF group and five in the CRF group. The penile erection ratio of the CRF group was 28% （7/25）, whereas that of the NCRF group was 100% （5/5）, which presents a significant difference between the two groups （P 〈 0.05）. In terms of penile erection frequency, the average of the CRF group was 1.0 ± 0.0, which was significantly different from that of the NCRF group （2.2 ± 0.8） （P 〈 0.05）. As for the expression of CX43 in the rat corpus cavernosum, a notable difference existed between the CRF group （0.21 ± 0.07） and the NCRF group （0.53 ± 0.27） （P 〈 0.01）. Conclusion： CRF significantly reduces the erectile function of rats. A close correlation exists between the expression of CX43 in rats＇ corpus cavernosum and CRF-related ED. （Asian J Andro12008 Mar; 10： 286-289）

Relationship between gene expression of nitric oxide synthase and androgens in rat corpus cavernosum

To clarify the dependence of neural nitric oxide synthase mRNA (nNOSmRNA) and endothelial nitric oxide synthase mRNA (eNOSmRNA) on androgens (testosterone[T] and dihydrotestosterone [DHT]) Methods 160 male Sprague Dawley (SD) rats were divided into Groups A (56 rats,5 weeks old),B (50rats,10 weeks old) and C (54 rats,58 weeks old) Groups A,B and C were all subdivided respectively into five Subgroups Subgroup 1: intact controls; Subgroup 2: castrated;Subgroup 3: castrated with testosterone undecanoate 25mg/kg·mon -1 ,intramuscular injection,Subgroup 4: castrated with testosterone undecanoate 50mg/kg·mon -1 ,intramuscular injection and Subgroup 5: treated with finasteride 4 5 mg/kg·day -1 ,orally Four and ten weeks after treatments described above,one half of the rats were killed Serum samples were taken for measurements of T, free testosterone (FT) and DHT by radioimmunoassay Penile samples were treated with liquid nitrogen and then stored at - 80℃ nNOSmRNA and eNOSmRNA were detected by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) and Dot blot Results There was no significant difference between Subgroup 1 and Subgroup 2 or Subgroup 5 in all Groups A, B and C The expression of penile eNOSmRNA of Group A was significantly increased (4weeks model) ( P <0 05) or increased (10 weeks model) ( P <0 05) in Subgroup 2 or 5 compared with those in Subgroup 1 There was no significant difference between Subgroup 1 and Subgroup 2 or Subgroup 5 of Group B in 4 weeks model ( P >0 05) There was an elevation when animals were castrated or treated with finasteride in the 10 weeks model The expression of penile eNOSmRNA of Group C was significantly increased (10 weeks model) ( P <0 05) or increased (4 weeks model) in Subgroup 2 compared with those in Subgroup 1 The production of eNOSmRNA in Subgroup 5 was also increased (including 4 and 10 week models) When T was supplied for castration, the penile eNOSmRNA was decreased to some extent;the greater the dose of T given,the lower penile eNOSmRNA was observed Conclusions The expression of eNOSmRNA in SD rat penile tissue increases while T or DHT diminishes Sometimes androgens modulate penile eNOSmRNA in opposite directions There is no correlation between the expression of nNOSmRNA and androgens (including T and DHT) Androgens give rise to penile erection probably not via the NOS pathway