title: Effect of hyperglycemia on expression of aquaporins in the rat vagina.
abstract: OBJECTIVE
  To investigate the effect of hyperglycemia on the expression of the aquaporin (AQP) isoforms in the diabetic rat vagina.
  
  
  METHODS
  Female Sprague-Dawley rats (230-240 g, n = 45) were divided into control (n = 10) and experimental (n = 35) groups. Diabetes in the experimental group was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). STZ-induced diabetic rats were left untreated or given subcutaneous injections of insulin (3 U/d). After 2 and 4 weeks, the blood glucose was measured, and the vaginal blood flow was assessed by Doppler flowmetry. The expression and cellular localization of AQP1 and AQP2 in the rat vagina were determined by Western blot and immunohistochemistry.
  
  
  RESULTS
  The vaginal blood flow (mL/min/100 g tissue) after pelvic nerve stimulation was significantly lower in the STZ-induced diabetic rats (21.9 ± 6.5 at 2 weeks and 21 ± 2.8 at 4 weeks) compared with the control group (55.5 ± 8.9 at 2 weeks and 52.9 ± 6.5 at 4 weeks; P < .05). In contrast, the vaginal blood flow response was significantly greater in the insulin-treated diabetic groups (47.7 ± 8.7 at 2 weeks and 47.7 ± 8.4 at 4 weeks) and comparable to that of the control group. The protein expression of AQP2 was significantly lower in the STZ-induced diabetic rats and was restored to the control level after insulin treatment. However, no change was seen in AQP1 expression. Thus, hyperglycemia might cause downregulation of AQP2 expression in the diabetic rat vagina.
  
  
  CONCLUSIONS
  These results suggest that decreased vaginal lubrication in diabetic women might result from changes in aquaporin expression, in addition to a reduction in the vaginal blood flow response.
authors.affiliation: Department of Urology, Chonnam National University Medical School, Sexual Medicine Research Center, Chonnam National University, Gwangju, Korea.
authors.forename: Hyun-Suk
authors.initials: HS
authors.lastname: Lee
authors.forename: Zhengri
authors.initials: Z
authors.lastname: Li
authors.forename: Sun-Ouck
authors.initials: SO
authors.lastname: Kim
authors.forename: Kyuyoun
authors.initials: K
authors.lastname: Ahn
authors.forename: Noel N
authors.initials: NN
authors.lastname: Kim
authors.forename: Kwangsung
authors.initials: K
authors.lastname: Park
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000096:biosynthesis*; D005260:Female; D006943:Hyperglycemia / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014621:Vagina / Q000378:metabolism*
chemical_list: D020346:Aquaporins