Alterations in urinary bladder synaptosomal neurotransmitter concentrations in two-week streptozotocin-induced diabetic rats

Effects of Moderate Alcohol Intake in the Bladder of the Otsuka Long Evans Tokushima Fatty Diabetic Rats

Diabetes is related with a number of cystopathic complications. However, there have been no studies about the influence of alcohol consumption in the bladder of type 2 diabetes. Thus, we investigated the effect of moderate alcohol intake in the bladder of the Otsuka Long Evans Tokushima Fatty (OLETF) diabetic rat. The non-diabetic Long-Evans Tokushima Otsuka (LETO, n=14) and the OLETF control group (n=14) were fed an isocaloric diet; the LETO (n=14) and the OLETF ethanol group (n=14) were fed 36% ethanol 7 g/kg/day. After ten weeks, muscarinic receptors, RhoGEFs, myogenic change, and the level of oxidative stress were evaluated. Moderate alcohol intake significantly decreased excessive muscarinic receptor and Rho kinase expressions in the OLETF rats compared with the LETO rats. In addition, iNOS and collagen expression were not changed in the OLETF rats in spite of alcohol consumption. Superoxide dismutase levels, which is involved in antioxidant defense, in the LETO rats were significantly decreased after alcohol consumption, however those in the OLETF rats were similar. Moderate alcohol consumption reduces the oxidative stress, and may prevent molecular and pathologic changes of the bladder of rats with type 2 diabetes.

Muscarinic receptors and their mRNAs in type 2 Goto-Kakizaki diabetic rat prostate

BACKGROUND

As increasing evidence is pointing towards the relationship between diabetes and benign prostatic hyperplasia/lower urinary tract symptoms, we investigated the pharmacological properties and gene expressions of the muscarinic receptors in type 2 diabetes rat prostate.

METHODS

Twelve- and 70-week-old male Goto-Kakizaki (GK) rats and age-matched male Wistar rats were used in this study. The densities of muscarinic receptors (B(max) values) were determined by saturation studies with [(3)H]NMS ([N-methyl-(3)H] scopolamine methyl chloride) in the prostatic membrane particulates. The participation levels of M(1), M(2), and M(3) receptor protein and mRNA levels in the prostate were investigated by immunoblot analysis and real-time polymerase chain reaction (PCR), respectively.

RESULTS

The B(max) values in 12-week-old Wistar and GK, and in 70-week-old Wistar and GK rat prostates were 36.0 +/- 2.8, 49.4 +/- 11.4, 22.0 +/- 2.2, and 47.0 +/- 4.1 fmol/mg protein, respectively. However, there were no significant differences in the affinity constants between any groups. Immunoblot analysis showed the existence of significant amounts of M(1), M(2), and M(3) receptor subtypes in each rat prostate. According to real-time PCR studies the rank order of expression levels of muscarinic receptors mRNA subtypes in the prostate were M(3) > M(2) > M(1). In each receptor subtype in each group, diabetes induced up-regulation of mRNAs while the advanced age of the rats was related with down-regulation of mRNAs.

CONCLUSIONS

Our data indicated that type 2 diabetes induced up-regulation and age-related down-regulation of the expressions of muscarinic receptors and their mRNAs in the rat prostate.

Nerve growth factor and substance P: expression in a rat model of diabetic bladder

OBJECTIVE

To evaluate the gene and protein expression of nerve growth factor (NGF) and substance P (SP) in the bladder 8 weeks after diabetes induction and investigate the pathogenesis of diabetic cystopathy.

METHODS

Thirty Wistar rats were divided into three groups: control (n = 10), streptozotocin-induced diabetic group (n = 10) and Pygeum africanum (P. africanum) group (n = 10; diabetic rats were given P. africanum (100 mg/kg/day)). Eight weeks later, the bladders were dissected. We measured the expression of NGF and SP in the bladders using RT-PCR, ELISA and immunohistochemistry.

RESULTS

We found a significantly reduced expression of NGF in the bladders from the diabetic group compared with the control. Immunohistochemical studies showed a statistically significant reduction of SP in the bladders from the diabetic group compared with the control (P < 0.05). Expression of NGF was greatly increased in the P. africanum group compared with that of the diabetic group. Immunohistochemical studies showed an increased level of SP in the bladders from the P. africanum group compared with the control (P < 0.05).

CONCLUSIONS

Our findings indicated that the decrease in NGF and SP may be a contributory factor in diabetic cystopathy. In addition, P. africanum could significantly upregulate the expression of NGF and SP in diabetic rats.

The protective effects of vitamin E on urinary bladder apoptosis and oxidative stress in streptozotocin-induced diabetic rats

OBJECTIVES

To determine whether vitamin E has protective effects or not on streptozotocin-induced diabetic rats in diabetic urinary bladder dysfunction, with interrelationships between oxidative stress and apoptosis.

METHODS

Thirty-two Wistar albino male rats were divided into 4 groups. Group A (n = 8), control; group B (n = 8), diabetic control; group C (n = 8), control + vitamin E; and group D (n = 8), diabetic + vitamin E. Vitamin E was injected 40 mg/kg every other day intraperitoneally for 2 weeks. In the diabetic groups, diabetes was induced by a single intraperitoneal injection of 65 mg/kg of streptozotocin. Apoptosis studies were performed using apoptosis detection kit and the TUNEL (TdT-mediated dUTP nick-end labeling) technique. The levels of glucose, malondialdehyde (MDA), superoxide dismutase, catalase, and glutathione peroxidase were detected in hemolysate.

RESULTS

It was observed that apoptosis number in urothelial cells of the bladder in diabetic rats increased significantly compared with control and decreased after vitamin E treatment. MDA levels of the diabetic group were significantly higher than those on the control and vitamin E groups. Diabetic + vitamin E group had significantly increased MDA levels compared with control group, although these values were lower than those in the diabetic group. All enzyme activities of the vitamin E group did not differ compared with the control group. In diabetic + vitamin E group, superoxide dismutase and glutathione peroxidase activities were similar to controls. Catalase activity of the diabetic + vitamin E group decreased significantly compared with control, although it was higher than that in the diabetic group.

CONCLUSIONS

Our study revealed that vitamin E decreases apoptosis and may be protective for uroepithelial cells of diabetic bladder.

Pharmacological properties, functional alterations and gene expression of muscarinic receptors in young and old type 2 Goto-Kakizaki diabetic rat bladders

PURPOSE

We investigated pharmacological properties, functional alterations and gene expression of the muscarinic receptor system in young and old Goto-Kakizaki rat bladders.

MATERIALS AND METHODS

Male 12 and 70-week-old Goto-Kakizaki rats and age matched male Wistar rats were used in this study. Bladder function was estimated by voiding behavior, cystometric and functional studies using KCl, carbachol and various concentrations of subtype selective muscarinic antagonists, ie pirenzepine, methoctramine, 4-DAMP (Sigma) and atropine (Wako Pure Chemical Industries, Osaka, Japan). The participation levels of M(2) and M(3) receptor mRNA in the bladder were investigated by real-time polymerase chain reaction.

RESULTS

In voiding behavior studies there were no significant differences in urine output, although an age related decrease in micturition frequency and an age related increase in single voided volume were observed in Goto-Kakizaki and Wistar rats. In cystometric studies there were no significant differences in maximum detrusor pressure or bladder capacity, although residual urine volume was significantly increased in 70-week-old Goto-Kakizaki rats. In functional studies carbachol induced detrusor contractility was significantly increased in Goto-Kakizaki rats in each age group. Estimated pA(2) values for atropine, pirenzepine, methoctramine and 4-DAMP (Sigma) indicated that the carbachol induced contractile response was mediated through the M(3) receptor subtype in all groups. Furthermore, muscarinic M(2) and M(3) receptor mRNA was significantly up regulated in 70-week-old Goto-Kakizaki rat bladders.

CONCLUSIONS

Our data indicate that noninsulin dependent diabetes induces alterations in the muscarinic receptor system, which may contribute to the development of diabetic cystopathy.

Role of hyperglycaemia in the pathogenesis of hypotension observed in type-1 diabetic rats

The role of hyperglycaemia in the pathogenesis of hypotension in diabetic disorders was investigated using the changes in cardiac M(2)-muscarinic receptor (M(2)-mAChR) gene expression in type-1-like diabetic rats and cultured cardiomyocytes. Blood pressure was markedly decreased in diabetic rats following the intravenous injection of streptozotocin (STZ) for 8 weeks. Also, the baroreflex sensitivity (Delta HR/Delta BP), as measured by the changes in heart rate (Delta HR) and mean blood pressure (Delta BP) 1 min after the intravenous injection of phenylephrine (10 microg/kg), was significantly increased. Arecaidine propargyl ester (APE), a M(2)-mAChR agonist produced a marked reduction in heart rate in these diabetic rats. Normalization of plasma glucose in diabetic rats using insulin (0.5 IU) or phlorizin (1 mg/kg) injection attenuated the blood pressure reduction and reversed the mRNA and protein levels of cardiac M(2)-mAChR. A high concentration of glucose (20 mmol/l) directly influenced the increase in gene expression of M(2)-mAChR in the H9c2 cardiac cell line. Hyperglycaemia induced an increase in cardiac M(2)-mAChR gene expression, suggesting a role in the pathogenesis of hypotension in diabetic disorders.

Time dependent changes in diabetic cystopathy in rats include compensated and decompensated bladder function

PURPOSE

Diabetic bladder dysfunction is among the most common and bothersome complications of diabetes mellitus. While bladder filling and voiding problems have been reported, the precise functional changes in diabetic bladders remain unclear. We investigated time dependent changes in bladder function in streptozotocin induced diabetic rats.

MATERIALS AND METHODS

Cystometrograms and detrusor muscle contractility were examined in male age matched control and diabetic Sprague-Dawley rats (Harlan, Indianapolis, Indiana) 3, 6, 9, 12 and 20 weeks after diabetes induction with streptozotocin.

RESULTS

Diabetes decreased average body weight and increased bladder weight, capacity and compliance. Peak detrusor leak pressure increased gradually from weeks 3 to 6 to 9 in diabetic rats (mean +/- SEM 47.3 +/- 2.5, 50.8 +/- 3.0 and 56.0 +/- 3.6 cm H(2)O) and in controls (36.9 +/- 1.4, 37.7 +/- 1.5 and 41.6 +/- 1.81 cm H(2)O, respectively). However, at 12 and 20 weeks diabetic rats deviated strongly from this trend with peak detrusor leak pressure decreasing vs controls (41.6 +/- 2.8 and 37.3 +/- 0.9 vs 45.2 +/- 1.7 and 49.6 +/- 1.4 cm H(2)O, respectively) and post-void resting pressures increasing from 9-week levels vs controls (interactions p <0.0001). In contractility studies increased contractile force responses of diabetic animals to carbamylcholine chloride, potassium chloride, adenosine 5'-triphosphate and electric field stimulation peaked at 6 or 9 weeks but at 12 to 20 weeks they generally reverted toward those of controls (carbamylcholine chloride and electrical field stimulation interactions p = 0.0022 and 0.01, respectively).

CONCLUSIONS

Diabetic bladders may undergo a transition from a compensated to a decompensated state and transition in the streptozotocin rat model may begin 9 to 12 weeks after induction.

Increased basal phosphorylation of detrusor smooth muscle myosin in alloxan-induced diabetic rabbit is mediated by upregulation of Rho-kinase β and CPI-17

Urinary bladder dysfunction caused by the alteration of detrusor smooth muscle (DSM) is one of the complications of diabetes. It is well established that smooth muscle contractility is regulated by an elevation of cytosolic Ca2+ via myosin light chain (MLC) phosphorylation. However, recent studies have shown the modulation of MLC phosphorylation without a rise in Ca2+ in smooth muscle and that two key molecules (Rho-kinase and CPI-17) are involved in the regulation of calcium sensitization. This study investigates the effect of diabetes on DSM calcium sensitization. Diabetes was induced by alloxan in New Zealand White rabbits, and age-matched rabbits given 5% sucrose in the drinking water served as control for diuresis. Two-dimensional gel electrophoresis showed that basal MLC phosphorylation level was significantly higher in diabetic animals than normal or diuretic controls, and Rho-kinase-specific inhibitor, Y-27632, decreased MLC phosphorylation level. Adding Y-27632 to bethanechol-precontracted DSM strips can induce muscle relaxation, but it occurred much more slowly in diabetic samples compared with controls. RT-PCR, Western blot analysis, and immunohistochemistry revealed the overexpression of Rho-kinase β and CPI-17 at both mRNA and protein levels in response to diabetes. In conclusion, our results demonstrate that Rho-kinase contributes to DSM MLC phosphorylation and there is a higher basal MLC phosphorylation level in diabetic DSM. Our results also suggest that this high basal MLC phosphorylation may be due to the upregulation of Rho-kinase and CPI-17. Thus Rho-kinase- and CPI-17-mediated Ca2+ sensitization might play a role in diabetes-induced alteration of the detrusor contractility and bladder dysfunction.

Oxidative stress plays a role in diabetes-induced bladder dysfunction in a rat model

OBJECTIVES

To evaluate the oxidative status of the bladder 8 weeks after diabetes induction. Oxidative stress has recently been implicated in the pathogenesis of diabetes complications, but its role in diabetic cystopathy has not been studied.

METHODS

Sprague-Dawley rats were divided into three groups: control (n = 11), diuretic control (5% sucrose drink; n = 6), and streptozotocin-induced diabetic group (n = 14). Eight weeks later, the bladders were dissected. We measured the antioxidant scavenging enzymes (catalase and superoxide dismutase)-like activity and the levels of the thiobarbituric acid reactive substances, as a marker of lipid peroxidation. We also examined the levels of inducible nitric oxide synthase and apoptosis in the bladders.

RESULTS

We found a statistically significant reduction in the catalase-like activity in the bladders from the diabetic group compared with the other groups (P = 0.017, diabetic versus control); the difference in the superoxide dismutase-like activity was not statistically significant among the groups. The thiobarbituric acid reactive substances levels were significantly greater in the diabetic compared with other groups (131.9 +/- 47.5, 46.7 +/- 17.9, and 60.9 +/- 25.4 nmol/mg protein in the diabetic, control, and diuretic group, respectively, P = 0.006, diabetic versus control). Immunohistochemical and apoptosis studies showed a statistically significant increased number of inducible nitric oxide synthase-positive cells and apoptotic cells in the diabetic bladder smooth muscle cells (P <0.001).

CONCLUSIONS

Our findings showed that oxidative stress occurred in the bladders of the STZ-diabetic rats and was not mediated by diuresis. The oxidative damage of the smooth muscle cells may be a contributory factor in diabetic cystopathy.

The role of sorbitol pathway and treatment effect of aldose reductase inhibitor ONO2235 in the up-regulation of cardiac M2-muscarinic receptors in streptozotocin-induced diabetic rats

This study investigated the role of the sorbitol pathway on the genetic up-regulation of the cardiac M(2) muscarinic receptor (M(2)-mAChR) in streptozotocin (STZ)-induced diabetic rats. Three-month-old male Wistar rats were divided into five groups: (1) normal controls; (2) rats rendered diabetic by streptozotocin; (3) rats fed with glucose; (4) rats injected with sorbitol; and (5) diabetic rats treated with ONO-2235, an aldose reductase inhibitor. The M(2) muscarinic receptor (M(2)-mAChR) protein and mRNA densities of the heart tissue were measured by Western immunoblotting and Northern blotting, respectively. The densities of M(2)-mAChR protein and mRNA in the heart were significantly increased in diabetic rats, and rats given either glucose or sorbitol. When diabetic rats were treated with ONO-2235, the increases in heart M(2)-mAChR protein and mRNA were significantly reduced. The findings suggest that hyperglycemia and the sorbitol pathway are involved in the pathogenesis of diabetic heart disease in STZ-induced diabetic rats. Aldose reductase inhibitors may be useful in the treatment and prevention of cardiac complication in diabetes.

Effects of Ba-Wei-Die-Huang-Wan on the cholinergic function and protein expression of M2 muscarinic receptor of the urinary bladder in diabetic rats

The study investigated the effect of a traditional Chinese herbal preparation 'Ba-Wei-Die-Huang-Wan' on the cholinergic function of the urinary bladder in diabetic rats, as well as its influence on the protein expression of muscarinic M(2) receptors. Wistar rats were divided into three groups: (1) control rats; (2) 2-week streptozotocin-induced diabetic rats; and (3) diabetic rats treated with Ba-Wei-Die-Huang-Wan 26 mg/kg thrice daily for 3 days. A dose-response study was performed for bladder muscle strip contractile response to a muscarinic agonist, arecaidine propargyl ester (APE). The amount of M(2) receptor protein in the bladder was measured by Western immunoblotting using monoclonal antibodies. The bladder contractile response to APE was significantly increased in the diabetic rats compared to the control. The M(2) receptor protein density was also significantly higher by 106% (P < 0.01, n = 8) in diabetes. Ba-Wei-Die-Huang-Wan treatment significantly lowered the plasma glucose level of the diabetic rats. The increases in contractile response to APE as well as the M(2) receptor protein density were partially reversed by the treatment. In conclusion, there was an over-expression of M(2) receptor resulting in hyper-contractility in the bladder of diabetic rats. Ba-Wei-Die-Huang-Wan significantly alleviated the alterations.

Smooth muscle of the bladder in the normal and the diseased state: pathophysiology, diagnosis and treatment

The smooth muscle of the normal bladder wall must have some specific properties. It must be very compliant and able to reorganise itself during filling and emptying to accommodate the change in volume without generating any intravesical pressure, but whilst maintaining the normal shape of the bladder. It must be capable of synchronous activation to generate intravesical pressure at any length to allow voiding. The cells achieve this through spontaneous electrical activity combined with poor electrical coupling between cells, and a dense excitatory innervation. In the diseased state, alterations of the smooth muscle may lead to failure to store or failure to empty properly. The diseased states discussed are bladder instability and diabetic neuropathy. Bladder instability is characterised urodynamically by uninhibitable rises in pressure during filling, and is seen idiopathically and in association with bladder outflow obstruction and neuropathy. In diabetic neuropathy, many of the smooth muscle changes are a consequence of diuresis, but there is evidence for alterations in the sensory arm of the micturition reflex. In the unstable bladder, additional alterations of the smooth muscle are seen, which are probably caused by the patchy denervation that occurs. The causes of this denervation are not fully established. Nonsurgical treatment of instability is not yet satisfactory; neuromodulation has some promise, but is expensive, and the mechanisms poorly understood. Pharmacological treatment is largely through muscarinic receptor blockade. Drugs to reduce the excitability of the smooth muscle are being sought, since they may represent a better pharmacological option.