Effect of insulin treatment on tissue size of the genitourinary tract in BB rats with spontaneously developed and streptozotocin-induced diabetes

Established and emerging treatments for diabetes-associated lower urinary tract dysfunction

Dysfunction of the lower urinary tract (LUT) including urinary bladder and urethra (and prostate in men) is one of the most frequent complications of diabetes and can manifest as overactive bladder, underactive bladder, urinary incontinence, and as aggravated symptoms of benign prostate hyperplasia. We have performed a selective literature search to review existing evidence on efficacy of classic medications for the treatment of LUT dysfunction in diabetic patients and animals, i.e., α1-adrenoceptor and muscarinic receptor antagonists, β3-adrenoceptor agonists, and phosphodiesterase type 5 inhibitors. Generally, these agents appear to have comparable efficacy in patients and/or animals with and without diabetes. We also review effects of antidiabetic medications on LUT function. Such studies have largely been performed in animal models. In the streptozotocin-induced models of type 1 diabetes, insulin can prevent and reverse alterations of morphology, function, and gene expression patterns in bladder and prostate. Typical medications for the treatment of type 2 diabetes have been studied less often, and the reported findings are not yet sufficient to derive robust conclusions. Thereafter, we review animal studies with emerging medications perhaps targeting diabetes-associated LUT dysfunction. Data with myoinositol, daidzein, and with compounds that target oxidative stress, inflammation, Rac1, nerve growth factor, angiotensin II receptor, serotonin receptor, adenosine receptor, and soluble guanylyl cyclase are not conclusive yet, but some hold promise as potential treatments. Finally, we review nonpharmacological interventions in diabetic bladder dysfunction. These approaches are relatively new and give promising results in preclinical studies. In conclusion, the insulin data in rodent models of type 1 diabetes suggest that diabetes-associated LUT function can be mostly or partially reversed. However, we propose that considerable additional experimental and clinical studies are needed to target diabetes itself or pathophysiological changes induced by chronic hyperglycemia for the treatment of diabetic uropathy.

Injury-Induced HSP27 Expression in Peripheral Nervous Tissue Is Not Associated with Any Alteration in Axonal Outgrowth after Immediate or Delayed Nerve Repair

We investigated injury-induced heat shock protein 27 (HSP27) expression and its association to axonal outgrowth after injury and different nerve repair models in healthy Wistar and diabetic Goto-Kakizaki rats. By immunohistochemistry, expression of HSP27 in sciatic nerves and DRG and axonal outgrowth (neurofilaments) in sciatic nerves were analyzed after no, immediate, and delayed (7-day delay) nerve repairs (7- or 14-day follow-up). An increased HSP27 expression in nerves and in DRG at the uninjured side was associated with diabetes. HSP27 expression in nerves and in DRG increased substantially after the nerve injuries, being higher at the site where axons and Schwann cells interacted. Regression analysis indicated a positive influence of immediate nerve repair compared to an unrepaired injury, but a shortly delayed nerve repair had no impact on axonal outgrowth. Diabetes was associated with a decreased axonal outgrowth. The increased expression of HSP27 in sciatic nerve and DRG did not influence axonal outgrowth. Injured sciatic nerves should appropriately be repaired in healthy and diabetic rats, but a short delay does not influence axonal outgrowth. HSP27 expression in sciatic nerve or DRG, despite an increase after nerve injury with or without a repair, is not associated with any alteration in axonal outgrowth.

Can Antidiabetic Drugs Improve Male Reproductive (Dys)Function Associated with Diabetes?

The alarming increase in the number of diabetic patients worldwide raises concerns regarding the impact of the disease on global health, not to mention on social and economic aspects. Furthermore, the association of this complex metabolic disorder with male reproductive impairment is worrying, mainly due to the increasing chances that young individuals, at the apex of their reproductive window, could be affected by the disease, further contributing to the disturbing decline in male fertility worldwide. The cornerstone of diabetes management is glycemic control, proven to be effective in avoiding, minimizing or preventing the appearance or development of disease-related complications. Nonetheless, the possible impact of these therapeutic interventions on male reproductive function is essentially unexplored. To address this issue, we have made a critical assessment of the literature on the effects of several antidiabetic drugs on male reproductive function. While the crucial role of insulin is clear, as shown by the recovery of reproductive impairments in insulin-deficient individuals after treatment, the same clearly does not apply to other antidiabetic strategies. In fact, there is an abundance of controversial reports, possibly related to the various study designs, experimental models and compounds used, which include biguanides, sulfonylureas, meglitinides, thiazolidinediones/glitazones, bile acid sequestrants, amylin mimetics, as well as sodiumglucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP1), α-glucosidase inhibitors and dipeptidyl peptidase 4 (DPP4) inhibitors. These aspects constitute the focus of the current review.

Clinical Efficacy of Solifenacin in the Management of Diabetes Mellitus-Associated Versus Idiopathic Overactive Bladder Symptoms: A Multicenter Prospective Study

Purpose

To compare the clinical efficacy of anticholinergics for managing diabetes mellitus-associated overactive bladder (DM OAB) versus idiopathic overactive bladder (OAB) in Korean women.

Methods

We conducted a multicenter, prospective, parallel-group, open-label, 12-week study. Women (20–65 years old) with OAB symptoms for over 3 months were assigned to the DM OAB and idiopathic OAB groups. Changes in the Overactive Bladder Symptom Score (OABSS), urgency, urinary urgency incontinence, nocturia, daytime frequency according to a voiding diary, uroflowmetry, and postvoid residual urine volume (PVR) at the first visit (V1), week 4 (V2), and week 12 (V3) were compared.

Results

No significant difference was found between the baseline patient characteristics of the DM OAB and idiopathic OAB groups. Treatment with solifenacin was associated with improvements in urgency, urinary urgency incontinence, nocturia, frequency according to a voiding diary, and the total OABSS between V1 and V2 and between V1 and V3. Moreover, a significant improvement in urgency and urge incontinence was found between V2 and V3 in the DM OAB group. However, no significant changes were found in any other parameters. There were no significant differences between the DM OAB group and the idiopathic OAB group except for urgency and urge incontinence at V2 (3.71 vs. 2.28 and 0.47 vs. 0.32, respectively).

Conclusions

The patients who received solifenacin demonstrated improved urgency, urinary urgency incontinence, nocturia, frequency according to a voiding diary, and total OABSS. Management with solifenacin was equally effective for both DM-related OAB and idiopathic OAB.

Influence of Melatonin on the Proliferative and Apoptotic Responses of the Prostate under Normal and Hyperglycemic Conditions

The antitumor properties of melatonin (MLT) are known for prostate cancer cells. This study investigated whether MLT affects prostate maturation and interferes with tissue injuries induced by diabetes. MLT was administered to Wistar rats from 5 weeks of age in the drinking water (10 μg/kg b.w.), and diabetes was induced at the 13th week by streptozotocin (4.5 mg/100g b.w., i.p.). The animals were euthanized in the 14th and 21st weeks. MLT reduced the immunostained cells for androgen receptor (AR) by 10% in younger rats. Diabetes decreased cell proliferation and increased apoptosis. MLT treatment impeded apoptosis (p = 0.02) and augmented proliferation (p = 0.0008) and PCNA content in prostate following long-term diabetes due to restoration of testosterone levels and expression of melatonin receptor type 1B. The effect of MLT (500 µM, 5 mM, and 10 mM) on androgen-dependent (22Rv1) and androgen-independent (PC3) cancer cells and human prostate epithelial cells (PNTA1) under normal and hyperglycemic conditions (HG, 450 mg/dL) was analyzed. Contrary to PNTA1 and 22Rv1 cells, MLT improved the proliferation of PC3 cells in hyperglycemic medium. The combined data indicated that MLT had proliferative and antiapoptotic effects in prostate cells subjected to HG levels and it seems to involve specific MLT pathways rather than AR.

A comprehensive review of urologic complications in patients with diabetes

Diabetes Mellitus (DM) is a chronic disease characterized by hyperglycemia, as a result of abnormal insulin production, insulin function, or both. DM is associated with systemic complications, such as infections, neuropathy and angiopathy, which involve the genitourinary tract. The three most significant urologic complications include: bladder cystopathy, sexual dysfunction and urinary tract infections. Almost half of the patients with DM have bladder dysfunction or cystopathy, which can be manifested in women as hypersensitivity (in 39-61% of the diabetic women) or neurogenic bladder. In males it can be experienced as lower urinary tract symptoms (in 25% of diabetic males with a nearly twofold increased risk when seen by age groups). Additionally, an increased prostate volume affects their micturition as well as their urinary tract. Involving sexual dysfunction in women, it includes reduced libido, decreased arousal, clitoral erectile dysfunction and painful or non-sensitive intercourse; and in diabetic males it varies from low libido, ejaculatory abnormalities and erectile dysfunction. Globally, sexual disorders have a prevalence of 18-42%. Erectile dysfunction is ranked as the third most important complication of DM. Urinary tract infections are observed frequently in diabetic patients, and vary from emphysematous infections, Fournier gangrene, staghorn infected lithiasis to repetitive bacterial cystitis. The most frequent finding in diabetic women has been lower urinary tract infections. Because of the high incidence of obesity worldwide and its association with diabetes, it is very important to keep in mind the urologic complication associated with DM in patients, in order to better diagnose and treat this population.

Gender differences in nerve regeneration after sciatic nerve injury and repair in healthy and in type 2 diabetic Goto-Kakizaki rats

Background

In view of the global increase in diabetes, and the fact that recent findings indicate that diabetic neuropathy is more frequently seen in males, it is crucial to evaluate any gender differences in nerve regeneration in diabetes. Our aim was to evaluate in short-term experiments gender dissimilarities in axonal outgrowth in healthy and in genetically developed type 2 diabetic Goto-Kakizaki (GK) rats, and also to investigate the connection between activated (i.e. ATF-3, Activating Transcription Factor 3) and apoptotic (cleaved caspase 3) Schwann cells after sciatic nerve injury and repair. Female and male diabetic GK rats, spontaneously developing type 2 diabetes, were compared with corresponding healthy Wistar rats. The sciatic nerve was transected and instantly repaired. After six days the nerve was harvested to measure axonal outgrowth (i.e. neurofilament staining), and to quantify the number of ATF-3 (i.e. activated) and cleaved caspase 3 (i.e. apoptotic) stained Schwann cells using immunohistochemistry.

Results

Axonal outgrowth was generally longer in male than in female rats and also longer in healthy than in diabetic rats. Differences were observed in the number of activated Schwann cells both in the distal nerve segment and close to the lesion site. In particular the female diabetic rats had a lower number. There were no gender differences in number of cleaved caspase 3 stained Schwann cells, but rats with diabetes exhibited more (such cleaved caspase 3 stained Schwann) cells both at the lesion site and in the distal part of the sciatic nerve. Axonal outgrowth correlated with the number of ATF3 stained Schwann cells, but not with blood glucose levels or the cleaved caspase 3 stained Schwann cells. However, the number of cleaved caspase 3 stained Schwann cells correlated with the blood glucose level.

Conclusions

We conclude that there are gender differences in nerve regeneration in healthy rats and in type 2 diabetic GK rats.

Therapeutic modulation of urinary bladder function: multiple targets at multiple levels

Storage dysfunction of the urinary bladder, specifically overactive bladder syndrome, is a condition that occurs frequently in the general population. Historically, pathophysiological and treatment concepts related to overactive bladder have focused on smooth muscle cells. Although these are the central effector, numerous anatomic structures are involved in their regulation, including the urothelium, afferent and efferent nerves, and the central nervous system. Each of these structures involves receptors for—and the urothelium itself also releases—many mediators. Moreover, hypoperfusion, hypertrophy, and fibrosis can affect bladder function. Established treatments such as muscarinic antagonists, β-adrenoceptor agonists, and onabotulinumtoxinA each work in part through their effects on the urothelium and afferent nerves, as do α1-adrenoceptor antagonists in the treatment of voiding dysfunction associated with benign prostatic hyperplasia; however, none of these treatments are specifically targeted to the urothelium and afferent nerves. It remains to be explored whether future treatments that specifically act at one of these structures will provide a therapeutic advantage.

Does concomitant diabetes affect treatment responses in overactive bladder patients?

AIMS

To compare the efficacy and tolerability of a muscarinic receptor antagonist, darifenacin, in the treatment of overactive bladder (OAB) patients with concomitant diabetes as compared with those without comorbidities.

METHODS

Post hoc exploratory analysis of a published, large, non-interventional study in OAB patients treated with darifenacin including 532 diabetics and 1315 controls. Associations of diabetes with treatment responses were evaluated by multiple regression models.

RESULTS

Diabetics (largely type 2 patients) and controls differed in baseline age, body weight, duration of OAB symptoms and presence of co-medications. However, they exhibited similar OAB symptom episode frequency and problem rating and received similar starting doses of darifenacin. Presence of diabetes was associated with a significantly smaller reduction of OAB symptoms, but the effect attributable to diabetes was small relative to the overall treatment response. The presence of diabetes was not associated with differences in tolerability.

DISCUSSION AND CONCLUSIONS

We conclude that a muscarinic receptor antagonist has comparable efficacy and tolerability in the treatment of OAB patients with and without concomitant diabetes.

Short-term stromal alterations in the rat ventral prostate following alloxan-induced diabetes and the influence of insulin replacement

The stromal microenvironment is pivotal to prostate physiology and malign transformation. Diabetes leads to testosterone withdrawal and affects the prostate stromal compartment and smooth muscle cells in a similar way to that observed after castration. However the response of these cells and their involvement in extracellular matrix remodeling is not satisfactorily understood. We investigated the changes caused in the short term (one week) by alloxan-induced diabetes in the stromal components of the rat ventral prostate (VP) with an emphasis on morphological alterations of stromal cells, their conversion to a myofibroblast phenotype and the remodeling of extracellular matrix and the influence of insulin therapy. Adult male Wistar rats were assigned into untreated diabetic (n=12), insulin-treated (n=8) diabetic and control (n=10) groups. Diabetes was induced by means of the injection of alloxan (40 mg/kg b.w.), while the control animals received saline solution only. Insulin (5 UI) was administered daily for one week after diabetes diagnosis. Testosterone and estrogen plasma levels were determined. VP was analyzed using transmission electron microscopy. The main stromal cells were identified by means of light microscopy, using immunocytochemistry for specific markers - vimentin for fibroblasts, α-actin for smooth muscle cells (smc) and vimentin/calponin for myofibroblasts, following the estimation of their relative frequency and absolute volume by means of stereology. After one week diabetes led to a marked decrease in testosterone levels and an atrophy of about 35% in the VP. The relative frequency of smc and collagen fibers increased in the VP of diabetic rats but their absolute weight remained unchanged. Experimental diabetes promptly altered smc morphology which assumed at the ultrastructural level a shrunken appearance with the approximation of cytoplasmic dense bodies and also exhibited a decreased immunoreactivity to calponin. The conversion of stromal cells to a myofibroblast phenotype did not occur in alloxan-induced diabetes, as evaluated by double immunoreaction to calponin and vimentin. Insulin treatment maintained testosterone levels and preserved at least partly the cell morphology and collagen fiber organization of the prostate stroma in short-term diabetes. The apparent collagen increase observed by means of microscopic analysis in the stromal prostate compartment in the short term after diabetes is mainly associated with gland atrophy and does not involve the formation of new collagen fibers, the generation of myofibroblast-like cells or the acquisition of a secretory phenotype by stromal cells.

Role of interleukins, IGF and stem cells in BPH

The condition known as benign prostatic hyperplasia may be defined as a benign enlargement of the prostate gland resulting from a proliferation of both benign epithelial and stromal elements. It might also be defined clinically as a constellation of lower urinary tract symptoms (LUTSs) in aging men. The purpose of this review is to consider the ways in which inflammatory cytokines belonging to the interleukin family, members of the IFG family, and stem cells may contribute to the development and progression of BPH-LUTS. This might occur in three mechanisms: One, interleukin signaling, IFG signaling and stem cells may contribute to reactivation of developmental growth mechanisms in the adult prostate leading to tissue growth. Two, given that epidemiologic studies indicate an increased incidence of BPH-LUTS in association with obesity and diabetes, IFG signaling may provide the mechanistic basis for the effect of diabetes and obesity on prostate growth. Three, expression of interleukins in association with inflammation in the prostate may induce sensitization of afferent fibers innervating the prostate and result in increased sensitivity to pain and noxious sensations in the prostate and bladder and heightened sensitivity to bladder filling.

Relative influence of testosterone and insulin in the regulation of prostatic cell proliferation and growth

Prostatic hyperplasia is a common problem of the aged men population. Recent experimental and clinical studies provide sufficient evidence that apart from androgens, insulin also plays an important role in the pathogenesis of prostatic hyperplasia. The present study was aimed to investigate the relative influence of testosterone and insulin on the cellular proliferation and prostatic growth. Effect of testosterone on the prostate of hypoinsulinemic, and glandular injection of insulin-receptor antagonist S961 on the prostate of castrated Sprague-Dawley rat (220±10 g) was examined. Significant decrease in the weight of the ventral prostate was observed in the streptozotocin-induced hypoinsulinemic rats (~6 fold), which is restored by the intervention of testosterone. Although, glandular injection of S961 did not led to any change in the frequency of proliferating cell nuclear antigen (PCNA) positive cells in normal rats, significant decrease was observed in the castrated rats. Castration led to increase in the frequency of the caspase-3 and the TUNEL positive cells in the ventral prostate. Further, long-term (6 weeks) administration of S961 induced significant decrease in the weight of the ventral prostate. Results of the present study provide that both testosterone and insulin promote prostatic cell proliferation and change in the level of either of the hormone results in the destabilization of cellular equilibrium, and modulation of the insulin-receptor signaling in the prostate may provide an alternative strategy for the treatment of prostatic enlargement. Further, studies are required to better understand the interplay between these hormones in the regulation of prostatic growth.

Role of insulin and testosterone in prostatic growth: who is doing what?

Previous studies have demonstrated increased incidence of benign prostatic hyperplasia in insulin-resistant individuals. In addition to androgens, prostatic growth is sensitive to the peptide growth factors including insulin. Experimental studies employing intervention of selective β-cell toxin streptozotocin and castration suggest that depletion of either insulin or testosterone results in the severe prostatic atrophy (>80%). Exogenous testosterone and diet-induced experimental hyperinsulinemia induces prostatic enlargement in rats. Further, hyperinsulinemia sensitizes prostate towards the growth promoting effect of testosterone, and testosterone augments prostatic growth even in the hypoinsulinemic rats. However, in castrated rats diet-induced hyperinsulinemia fails to promote prostatic growth. Based on these evidences it is hypothesized that in the presence of testosterone insulin plays an important role in the prostatic growth. The epidemiological reports witnessing increased incidences of prostatic enlargement in men with metabolic syndrome, which are known to have increased level of insulin, provides a validating clue to the hypothesis. Further, the hypothesis suggests that targeting insulin signaling pathway could be a new objective for the treatment of prostatic enlargement.

Increased cell proliferation and contractility of prostate in insulin resistant rats: linking hyperinsulinemia with benign prostate hyperplasia

BACKGROUND

Obesity, dyslipidemia, Hyperinsulinemia, and insulin resistance (IR) are key features of metabolic syndrome and are considered as risk factors for benign prostatic hyperplasia (BPH) as well as type 2 diabetes. The present study was aimed to determine whether or not IR associated hyperinsulinemia contributes to the BPH.

METHODS

Sprague-Dawley rats (9 weeks) were used in the study. Rats were kept on high fat diet (HFD) for the induction of hyperinsulinemia while hypoinsulinemia was induced by streptozotocin. Effect of HFD feeding on the testosterone-induced prostatic growth was evaluated. Pioglitazone (PG, 20 mg/kg) was used for the reversal of compensatory hyperinsulinemia and to examine the subsequent effect on the prostatic growth.

RESULTS

Prostatic enlargement was observed in the HFD-fed rats. Significant increase in the cell proliferation markers confirmed the occurrence of cellular hyperplasia in the prostate of hyperinsulinemic rat. Enhanced alpha-adrenoceptor mediated contraction in the prostate of HFD-fed rats indicates augmented contractility of the gland. Higher level of phosphorylated-ERK suggests enhanced MEK/ERK signaling. HFD feeding has not led to change in the plasma testosterone level. However, testosterone treatment further augmented the prostatic growth in HFD-fed rats. PG treatment led to improved insulin sensitivity, decreased plasma insulin level and prostate weight, indicating the role of compensatory hyperinsulinemia in the prostate growth.

CONCLUSIONS

The present investigation reports that HFD-feeding induced hyperinsulinemic condition leads to increased cellular proliferation, enhanced alpha-adrenoceptor mediated contraction, and enlargement of the prostate in rats.

Malignant lesions in the ventral prostate of alloxan-induced diabetic rats

The aim of this study was to evaluate the changes caused by chronic diabetes in the rat ventral prostate and to establish a correlation between diabetes and the development of prostatic lesions. Male rats received alloxan (42 mg/kg b.w.) to induce diabetes. Ninety days after diabetes diagnosis, animals were sacrificed and the ventral prostate was removed and prepared for general and immunohistochemical analyses. The total area showing different types of lesions was estimated. Diabetes led to a decrease in the body and prostatic weights, as well as in testosterone levels. The prostate morphology and stereology showed high variation in the diabetic group. Some animals had light changes; the great majority had an intense epithelial atrophy; and other rats showed premalignant and malignant lesions in the prostate. Such epithelial atrophy was, in some samples, combined with chronic inflammation, similar to proliferative inflammatory atrophy (PIA). The diabetic group also presented high incidence of prostatitis, adenocarcinoma and prostatic intra-epithelial neoplasia (PIN). Samples with adenocarcinoma had poorly differentiated acini with high levels of cellular proliferation and nuclear atypia. These lesions exhibited an invasive feature showing Bcl-2-positive cells and interruptions in the basement membrane. An association of PIA, PIN and adenocarcinoma was detected in one sample. Reduced androgen levels have a synergic effect to insulin dysfunction promoting negative effects in the rat prostate. Diabetic individuals had a high incidence of prostatitis, and this inflammation could stimulate the incidence of other forms of prostatic pathology.

Differential effects of diabetes induced by streptozotocin and that develops spontaneously on prostate growth in Bio Breeding (BB) rats

We investigated molecular changes in the response to insulin in prostates of spontaneously developed (Bio Breeding) and streptozotocin (STZ)-induced diabetic rats that received sufficient amounts (euglycemic group), or suboptimal doses (hyperglycemic group) of insulin for 32 weeks, using Affymetrix GeneChip analysis of gene expression. Alterations in gene expression levels identified by microarray analysis, having potential biological relevance to prostate growth, were verified by real-time reverse transcription polymerase chain reaction (RT-PCR). A significant decrease in the weight of ventral prostate was observed in the hyperglycemic STZ-induced but not spontaneously developed diabetic group. Microarray analysis revealed that gene expression profiles were distinctly different in each region of the prostate, and that hyperglycemic diabetes in spontaneously developed and STZ-diabetic rats was associated with differential changes in the prostatic expression levels of 856 genes, of which 35 were related to cell growth, proliferation and death. RT-PCR data verified significant differences in the mRNA expression levels of Igfbp6, Tieg, and Clu between euglycemic and hyperglycemic groups, whereas expression levels of these genes in control and euglycemic diabetic groups were not significantly different. In ventral prostate, the mRNA expression levels of Igfbp6 and Tieg were significantly higher in the hyperglycemic STZ-induced diabetic than in the hyperglycemic spontaneously diabetic BBDP/Wor rats. Our data demonstrate that the diabetes induced by STZ in the BBDR/Wor rats affects prostate growth and the molecular response to insulin differently than that observed in BBDP/Wor rats that develop diabetes spontaneously.