Method for simultaneous recording of the prostatic contractile and urethral pressure responses in anesthetized rats and the effects of tamsulosin

Quisqualis indica extract ameliorates low urinary tract symptoms in testosterone propionate-induced benign prostatic hyperplasia rats

Benign prostate hyperplasia (BPH) is a common disease in old-age males, accounting for approximately 77% of morbidity within the age range of 40 to 70 years. It has been shown that morbidity increases with social graying. Quisqualis indica linn (QI) has been used to treat inflammation, stomach pain, and digestion problems. In this study, we evaluated the symptom-regulating effects of QI extract on a testosterone-induced BPH rat model. After inducing BPH in rats using testosterone propionate (TP) injection, we assessed basal intraurethral pressure (IUP) and increments of IUP elicited by electrical field stimulation (5 V, 5, 10, or 20 Hz) or phenylephrine (Phe) (0.01, 0.03, 0.1 mg/kg IV). To induce BPH, 8-week-old rats were subjected to a daily subcutaneous TP (3 mg/kg) injection for 4 weeks. Finasteride (Fina) (10 mg/kg PO) was administered to the rats in the first treatment, while QI (150 mg/kg PO) was administered to those in the second group. Blood pressure was measured together with IUP, after which low urinary tract (LUT), ventral prostate (VP), testicle, and corpus spongiosum were isolated and weighed. Basal IUPs for the Fina- and QI-treated groups were 87.6 and 86.8%, respectively.

LUT and VP organ weights in the QI group were lower than those in the Fina group. However, the QI group showed significantly reduced electrical stimulated or Phe-induced IUP increment compared to the Fina and BPH groups. These results proved that QI can be beneficial for BPH symptoms by inhibiting 5α-reductase and consequently decreasing prostate and releasing urinary pressure.

Additive effect of oral LDD175 to tamsulosin and finasteride in a benign prostate hyperplasia rat model

Objective

We investigated the benefits of the BK_Ca agonist 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid (LDD175) combined with tamsulosin and finasteride, in a benign prostatic hyperplasia (BPH) rat model.

Materials and methods

Castration was performed by bilateral orchiectomy under ketamine anesthesia. A rat model of BPH was established by daily intramuscular administration of testosterone propionate plus 17β-estradiol for 8 weeks. Model rats were administered combinations of 20 mg/kg LDD175, 0.01 mg/kg tamsulosin and 1 mg/kg finasteride once daily by oral gavage for 4 weeks from week 6 to 9 post-surgery. Intraurethral pressure induced by electrostimulation of the hypogastric nerve was measured at the end of administration. Body and genitourinary organ weights were recorded, serums were assayed for hormone concentrations, and tissues were subjected to histopathology, and analyses of α1-adrenoceptor mRNA and protein expression levels after treatment.

Results

Combined LDD175, tamsulosin, and finasteride significantly decreased prostatic index, serum hormone levels, epithelial thickness, and prostate expression of α1-adrenoceptors in BPH model rats. The 3-drug combination was more effective than any other combination or LDD175 alone.

Conclusion

These results suggest that LDD175 addition to tamsulosin and finasteride may be beneficial for the treatment of BPH patients who do not respond to tamsulosin plus finasteride.

Physiology and Pharmacology of Ejaculation

Ejaculation is the final stage of coitus in mammalian male and is mandatory for natural procreation. Two synchronized phases, emission and expulsion, form the ejaculatory response and involve specific organs and anatomical structures. The peripheral events leading to ejaculation are commanded by autonomic (sympathetic and parasympathetic) and somatic divisions of the nervous system. The autonomic and somatic motor efferents originate in spinal nuclei located in thoracolumbar and lumbosacral segments. Co-ordinated activation of autonomic and somatic spinal nuclei is orchestrated by a group of lumbar spinal interneurons defined as the spinal generator of ejaculation. The generator of ejaculation together with the autonomic and somatic spinal nuclei constitutes a spinal network that is under the strong influence of stimulating or inhibiting genital sensory and supraspinal inputs. A brain circuitry dedicated to ejaculation has been delineated that is part of a more global network controlling other aspects of the sexual response. This circuitry includes discrete neuronal populations distributed in all divisions of the brain. The corollary to the expanded CNS network is the variety of neurotransmitter systems participating in the ejaculatory process. Among them, serotonin neurotransmission plays a key role and its targeting led to the development of the first registered pharmacological treatment of premature ejaculation in human beings. Critical gaps remain in the understanding of neurophysiopharmacology of ejaculation and management of ejaculatory disorders in human beings needs improvement. Because the ejaculatory response in laboratory animals and in human beings shares many similarities, the use of animal models will certainly provide further advances in the field.

Effect of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid on the intraurethral pressure in a rat model of benign prostatic hyperplasia

OBJECTIVES

To investigate the effect of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid, a new benzofuroindole derivative, on the intraurethral pressure in a rat model of benign prostatic hyperplasia.

METHODS

Benign prostatic hyperplasia was induced by testosterone and 17β-estradiol, which were administered intramuscularly once a day for 12 weeks. The effects of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid and tamsulosin on the intraurethral pressure induced by the electrostimulation of hypogastric nerves after a single intravenous injection of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid (10 mg/kg) or tamsulosin (10 μg/kg) were evaluated in a benign prostatic hyperplasia model. The electrostimulation-induced intraurethral pressure was measured just before and after the injection of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid. Bodyweight and genitourinary organ weights were recorded, and serums and tissues were subjected to hormone assays and histopathology. In addition, the expression of α1-adrenoceptors in the prostate was measured by western blotting.

RESULTS

The benign prostatic hyperplasia groups showed increased prostatic index, increased concentrations of testosterone, free testosterone and estradiol in serum, and increased epithelial thickness of the prostate. An injection of 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid or tamsulosin significantly inhibited the elevation of electrostimulation-induced intraurethral pressure. In addition, 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid did not cause a significant change in the blood pressure compared with tamsulosin. While the benign prostatic hyperplasia group showed increased the expression of α1-adrenoceptors, the 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid or tamsulosin injection into a rat model of benign prostatic hyperplasia decreased the expression of α1-adrenoceptors.

CONCLUSIONS

These findings show that 4-chloro-7-trifluoromethyl-10H-benzo[4,5]furo[3,2-b]indole-1-carboxylic acid might be beneficial for lowering the intraurethral pressure associated with benign prostatic hyperplasia, and it could represent a therapeutic option for benign prostatic hyperplasia patients.

Anatomy and physiology of genital organs - men

Male sexual functions involve a number of organs and structures in genitalia whose role is to produce fertilizing gametes and to allow female-partner insemination. The testes belong to the reproductive and endocrine systems as they synthesize spermatozoa and androgens, and are under finely regulated hormonal control by the hypothalamopituitary axis. Sexual responses are controlled by a complex and coordinated interplay of both the somatic and the autonomic nervous system in multiple components of the brain, spinal cord, and relevant peripheral organs. Erectile bodies are an essential element of the penis and engorgement of the penis with blood leads to penile tumescence. Blood engorgement is due to relaxation of smooth-muscle cells of erectile tissue and endothelium of the penile arteries. The penis gains additional rigidity when the ischiocavernosus muscles contract. Stimuli from peripheral and/or central origins activate particular spinal nuclei, causing penile erection. Ejaculation consists of two phases, emission and expulsion, which correspond, respectively, to secretion of the different components of the semen by sex glands and forceful expulsion of semen due to rhythmic contractions of the bulbospongiosus muscle. A spinal generator of ejaculation integrates genital stimuli and sexual cues and, when the excitatory threshold is reached, triggers ejaculation by orchestrating the activation of autonomic and somatic pathways commanding the peripheral events of ejaculation.

Slimmer or fertile? Pharmacological mechanisms involved in reduced sperm quality and fertility in rats exposed to the anorexigen sibutramine

Sperm acquire motility and fertility capacity during epididymal transit, under the control of androgens and sympathetic innervations. It is already known that the acceleration of epididymal sperm transit time can lead to lower sperm quality. In a previous work we showed that rats exposed to the anorexigen sibutramine, a non-selective serotonin-norepinephrine reuptake inhibitor, presented faster sperm transit time, lower epididymal sperm reserves and potentiation of the tension of epididymal duct to norepinephrine exposed acutely in vitro to sibutramine. In the present work we aimed to further investigate pharmacological mechanisms involved in these alterations and the impact on rat sperm quality. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/day) or vehicle for 30 days. Sibutramine decreased final body, seminal vesicle, ventral prostate and epididymal weights, as well as sperm transit time in the epididymal cauda. On the contrary of the in vitro pharmacological assays, in which sibutramine was added directly to the bath containing strips of distal epididymal cauda, the ductal tension was not altered after in vivo sub-chronic exposure to sibutramine. However, there is pharmacological evidence that the endogenous epididymal norepinephrine reserves were reduced in these animals. It was also shown that the decrease in prostate weight can be related to increased tension developed of the gland, due to sibutramine sympathomimetic effects. In addition, our results showed reduced sperm quality after in utero artificial insemination, a more sensitive procedure to assess fertility in rodents. The epididymal norepinephrine depletion exerted by sibutramine, associated with decreases in sperm transit time, quantity and quality, leading to reduced fertility in this experimental model, reinforces the concerns about the possible impact on fertility of man taking sibutramine as well as other non-selective serotonin-norepinephrine reuptake inhibitors, especially considering the lower reproductive efficiency of humans compared to males of other species.

The Fate of Implanted Syngenic Muscle Precursor Cells in Injured Striated Urethral Sphincter of Female Rats

We studied the outcome of syngenic skeletal muscle precursor cells (MPCs) implanted in the striated urethral sphincter of the female rat. These cells were injected at the site of a longitudinal sphincterotomy performed 21 days before implantation. MPCs were isolated from the striated hindlimb muscles of syngenic adult rats and were infected with a retrovirus carrying the gene for either the green fluorescent protein (GFP) or the β-galactosidase enzyme (β-gal). MPCs (2 × 105) were injected longitudinally at the site of the lesion in 48 animals using a 10-μl Hamilton syringe. Then the whole urethras were excised from 2 h up to 90 days for cross section immunocytochemistry analysis. All the urethras exhibited connective tissue in place of the injury of the striated fibers. Two hours after injection a cluster of small round basophilic cells was observable at the site of injection and some of them expressed GFP or β-gal. A few GFP- and β-gal-positive cells were already detectable 7 days after injection. A large amount of injected cells probably died after injection. Many striated fibers of the urethra became GFP positive from day 7 until day 21, suggesting that few MPCs were allowed to incorporate the divided extremities of the striated fibers from day 7. Unfortunately, we did not observe centronucleated regenerated fibers in this experiment.

Effects of phosphodiesterase type 5 inhibitor on the contractility of prostate tissues and urethral pressure responses in a rat model of benign prostate hyperplasia

AIM

This study was performed to investigate the effect of DA-8159, a selective phosphodiesterase 5 (PDE5) inhibitor, on benign prostatic hyperplasia (BPH) both in vitro and in vivo.

METHODS

We assessed the influence of DA-8159 on the contractility of rat prostate tissues in an organ-bath experiment. In addition, in order to investigate whether chronic administration of DA-8159 prevents the increase of electrostimulation-induced intraurethral pressure (IUP) responses associated with BPH, BPH was induced by steroid hormones (testosterone plus 17beta-estradiol) and DA-8159 (5, 20 mg/kg) was concomitantly administered once a day for 8 weeks. After that the electrostimulation-induced IUP responses were measured. Finally, we investigated the acute treatment effect of DA-8159 on IUP responses in an established BPH model after a single intravenous injection of DA-8159 (0.3, 1 mg/kg).

RESULTS

DA-8159 concentration-dependently reduced the contraction of the isolated prostate strips with an IC50 value of 70 microM. In chronic treatment study, while the BPH control rats showed a significantly increased IUP both at the baseline and by electrostimulation, the chronic DA-8159 treatment significantly attenuated the increase in IUP responses in a dose- and frequency-dependent manner. In the acute treatment study, a single intravenous injection of DA-8159 also prevented the increase in urethral pressure in a dose-dependent manner.

CONCLUSIONS

These results suggest that DA-8159 may be beneficial on lowering the urethral pressure associated with BPH via dilatation of the prostate, but a further evaluation of the efficacy on humans needs to be performed.

The role of bladder-to-urethral reflexes in urinary continence mechanisms in rats

Urethral closure mechanisms during passive increments in intravesicular pressure (Pves) were investigated using microtip transducer catheters in urethane-anesthetized female rats. After a block of reflex bladder contractions by spinal cord transection at T8-T9, abruptly raising Pves to 20, 40, or 60 cmH2O for 2 min induced a bladder pressure-dependent contractile response in a restricted portion of the middle urethra (12.5–15 mm from the urethral orifice) that was abolished by cutting the pelvic nerves bilaterally. In pelvic nerve-intact rats, the bilateral transection of either the pudendal nerves, the nerves to the iliococcygeous/pubococcygeous muscles, or the hypogastric nerves significantly reduced (49–74%) the urethral reflex response induced by passive Pves increases, and combined transection of these three sets of nerves totally abolished the urethra-closing responses. In spinal cord-intact rats, similar urethral contractile responses were elicited during Pves elevation (20 or 40 cmH2O) and were also eliminated by bilateral pelvic nerve transection. After spinal cord and pelvic nerve transection, leak point pressures, defined as the pressure inducing fluid leakage from the urethral orifice during passive Pves elevation by either bladder pressure clamping in 2.5-cmH2O steps or direct compression of the bladder, were significantly lowered by 30–35% compared with sham-operated (spinal cord-transected and pelvic nerve-intact) rats. These results indicate that 1) passive elevation of Pves can elicit pelvic afferent nerve-mediated contractile reflexes in the restricted portion of the urethra mediated by activation of sympathetic and somatic nerves and 2) bladder-to-urethral reflexes induced by passive Pves elevation significantly contribute to the prevention of stress urinary incontinence.