Effects of ethanol and its metabolite acetaldehyde on responses of the rat bladder

Functional roles of TRPV1 channels in lower urinary tract irritated by acetic acid: in vivo evaluations of the sex difference in decerebrate unanesthetized mice

Sex-specific differences in activity of the lower urinary tract (LUT) responding to acid irritation in mice have been revealed. This study, using continuous infusion cystometry with acetic acid (AA; pH 3.0), was conducted to examine whether the transient receptor potential vanilloid type 1 (TRPV1) channels expressed in the mouse LUT are involved in the sex difference in functional responses of the bladder and urethra to irritation. No differences were found between effects of capsazepine (a TRPV1 blocker; 100 μM) and those of its vehicle on any of the cystometric changes by intravesical AA in either female or male mice. However, capsazepine eliminated the acid-induced sex differences in parameters associated with bladder contraction phase (i.e., maximal voiding pressure, closing peak pressure, 2nd-phase contraction, bladder contraction duration), whereas capsazepine did not affect those in parameters associated with bladder-filling period (i.e., intercontraction interval, actual collecting time). In males, capsazepine reduced the number of bladder contractions accompanying fluid dribbling at 2nd-phase contraction, which is indicative of the urethral response to irritation, whereas in females it increased the number. Together, these results suggest the possibilities that TRPV1 channels in the bladder and urethra are involved in the sex difference in the LUT response to acid irritation and that these participate, e.g., via “cross talk” between the bladder and urethra, in the fine-tuning of intravesical pressure (or bladder emptying) at the bladder contraction phase under irritated LUT conditions but not in sensing for bladder filling during the storage period, although the contribution of the mechanism may be small.

The association of diet and other lifestyle factors with the onset of overactive bladder: a longitudinal study in men

Objective:

To investigate associations between diet and non-dietary lifestyle factors and the onset of overactive bladder (OAB) in men.

Subjects:

Random sample of community-dwelling men aged 40 years plus.

Design and methods: Baseline data on urinary symptoms and diet were collected from 5454 men using a postal questionnaire and a food-frequency questionnaire. Follow-up data on urinary symptoms were collected from 4887 men in a postal survey one year later. Logistic regression analysis was used to investigate diet and lifestyle factors associated with onset of OAB in the men without OAB at baseline.

Results:

There was a highly significant negative association between beer intake at baseline and subsequent OAB onset (P = 0.001), with reduced risk at all levels of intake compared with those who seldom/never drank beer. Adjustment for total alcohol intake (g ethanol day−1) reduced the significance of the association (P = 0.02). None of the food groups studied was associated with OAB onset, with the possible exception of potatoes (P = 0.05), which showed an increased risk of onset at the highest level of consumption. Physical activity, smoking and obesity were not significantly associated.

Conclusions:

While most diet and lifestyle factors were not associated with OAB onset, the evidence from this prospective longitudinal study suggests that beer may have a protective role in the development of OAB. This could be due to a non-alcoholic ingredient as well as the alcohol content.

Effects of ethanol on intracorporeal structures of the rat

OBJECTIVE

Previous studies demonstrated that acute in vitro exposure of corpus cavernosal tissue to ethanol decreased its response to field stimulation and pharmacological stimulation. In the present study we investigated the effects of chronic ethanol consumption on the ultrastructure of cavernosal smooth muscle cells, elastic fibres and collagen content.

MATERIAL AND METHODS

Fourteen adult wistar rats were divided into a control group (n = 7, fed a standard diet and tap water) and an alcoholic group (n = 7, fed a standard diet and 5% (v/v) ethanol in drinking water and by increasing the ethanol concentration for every week, at the end of 6th week 30% (v/v) ethanol concentration was attained. Same dose was given until 12th week. At the end of 12th week blood samples were obtained and the ethanol concentrations were determined. The cavernosal tissues were obtained and immunohistochemical examinations were performed.

RESULTS

Immunohistochemical analysis revealed that chronic ethanol exposure markedly decreased the content of smooth muscle cells, elastic fibres and collagen type 4.

CONCLUSION

Our findings suggest that in this animal model chronic ethanol exposure decreases the percentage of staining for smooth muscle actin, elastin, and collagen type 4 which are the key structures fundamental for erection.

Effects of testosterone on neuromuscular transmission in rat isolated urinary bladder

Testosterone was examined for its effects on neuromuscular transmission in rat and shrew urinary bladder. In isolated preparations of detrusor muscle from sexually immature male rats (8-10 weeks old) at concentrations of 100-300 microM, it inhibited neuromuscular transmission in a concentration-dependent manner and it also inhibited responses to applied carbachol and diadenosine pentaphosphate (Ap(5)A, a P2X receptor agonist). Ethanol (at or above 38 mM), the solvent for testosterone, also caused significant inhibition of neurogenic contractions as well as carbachol- and Ap(5)A-induced contractions. In older, sexually mature male rats (over 16 weeks old), testosterone and ethanol had similar effects to those observed in the young male rat, although both were slightly less potent. In young virgin female rats (8-12 weeks old), testosterone and ethanol inhibited neuromuscular transmission; testosterone was approximately 1000 times more potent than in male rats, with a threshold concentration of 30 nM. In the insectivore, Suncus murinus, testosterone (0.1 microM-1 x mM) caused inhibition of neurogenic and chemogenic responses, but ethanol had no significant effect. Flutamide (50 microM), a genomic testosterone-receptor antagonist, did not inhibit any of the responses to testosterone. It is concluded that testosterone acts predominantly on a postjunctional nongenomic receptor to inhibit urinary bladder detrusor muscle contraction.