The effects of melatonin on ischemia-reperfusion induced changes in rat corpus cavernosum

Milrinone ameliorates ischaemia-reperfusion injury in experimental testicular torsion/detorsion rat model

This experimental study aims to evaluate the efficacy of milrinone against ischaemia-reperfusion injury due to testicular torsion/detorsion. Group 1 was defined as the control group. Testicular torsion/detorsion model was performed in Group 2. Group 3 had similar procedures to the rats in Group 2. In addition, 0.5 mg/kg of milrinone was administered intraperitoneally immediately after testicular torsion in Group 3. Histopathological examinations indicated a dramatic improvement in terms of inflammation, haemorrhage, oedema, congestion, Cosentino and Johnson scores in Group 3 compared to Group 2 (p = .037, p = .045, p = .018, p = .040, p = .033 and p = .03 respectively). Blood biochemical analyses, superoxide dismutase (SOD), glutathione peroxidase (GSH-px) activity and total antioxidant status (TAS) levels increased significantly in Group 3 compared to Group 2 (p = .001, p = .024 and p < .001). Malondialdehyde (MDA), protein carbonyl (PC), interleukin 1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and total oxidant status (TOS) levels decreased in Group 3 compared to Group 2 (p = .001, p = .018, p < .001, p = .036 and p = .002 respectively). Tissue biochemical analyses determined an increase in SOD and GSH-px activity in Group 3 compared to Group 2, while PC and MDA levels were reduced (p = .001, p < .001, p = .038 and p < .001 respectively). Milrinone attenuates ischaemia-reperfusion injury that causes highly harmful effects due to testicular torsion/detorsion.

Protective effects of dexmedetomidine on ischaemia-reperfusion injury in an experimental rat model of priapism

The study aimed to investigate the effects of dexmedetomidine against ischaemia-reperfusion injury occurring after priapism in a model of induced-priapism in rats. A total of 18 male rats were randomised into three groups. Group 1 was the control group. A priapism model was performed rats in Group 2 and then ischaemia-reperfusion injury was evaluated. Group 3 had similar procedures to the rats in Group 2. Rats in Group 3 additionally had 100 μg/kg dexmedetomidine administered intraperitoneally immediately after reperfusion. Blood and tissue samples were analysed. Biochemical analysis of blood samples revealed a decrease in the levels of the pro-inflammatory cytokines including interleukin-1 beta (IL-1 Beta), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha) in Group 3 compared to Group 2 (p:.04, p:.009 and p:.009, respectively). Similarly, the highest malondialdehyde (MDA) level was in Group 2 (p:.002). The levels of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were significantly higher in Group 3 than that of Group 2 (p:.037 and p:.045, respectively). Direct microscopic examinations revealed positive changes in desquamation, oedema, inflammation and vasocongestion scores in Group 3 compared to Group 2 (p:.007, p:.008, p:.007 and p:.006, respectively). Dexmedetomidine has a protective effect against ischaemia-reperfusion injury in penile tissue.

Exercise and caloric restriction improve cardiovascular and erectile function in rats with metabolic syndrome

The aim of this study is to examine the possible benefits of exercise and caloric restriction (CR) on cardiovascular hemodynamics, erectile function, and antioxidant system in metabolic syndrome (MS). Sixty male Spraque-Dawley rats were divided into five groups; control, MS, MS + CR, MS + exercise (EXC), and MS + CR + EXC. To induce MS, 10% fructose solution was applied for 3 months. Thereafter, in CR groups calorie was restricted 40% and in EXC groups swimming was performed for 6 weeks. Body weight, blood glucose, and blood pressure (BP) levels were measured before and after MS induction and at the end of the experiment. After decapitation, tumor necrosis factor (TNF)-α, adiponectin (ADP), and plasminogen activator inhibitor (PAI)-1 levels were investigated in blood, oxidative stress parameters were examined in heart, aorta, and corpus cavernosum (CC) tissues. Isometric contraction in isolated tissue bath was studied in aorta and CC tissues. Animals subjected to exercise and CR had decreased BP and blood glucose levels. Impaired contraction-relaxation responses in MS group were improved with exercise and CR. MS-induced increase in TNF-α, PAI-1, malondialdehyde (MDA), and decrease in ADP, glutathione (GSH), and superoxide dismutase (SOD) were normalized with exercise and CR. Exercise and CR may be beneficial against changes in cardiovascular hemodynamics caused by MS.

Melatonin as an antioxidant: under promises but over delivers

Melatonin is uncommonly effective in reducing oxidative stress under a remarkably large number of circumstances. It achieves this action via a variety of means: direct detoxification of reactive oxygen and reactive nitrogen species and indirectly by stimulating antioxidant enzymes while suppressing the activity of pro-oxidant enzymes. In addition to these well-described actions, melatonin also reportedly chelates transition metals, which are involved in the Fenton/Haber-Weiss reactions; in doing so, melatonin reduces the formation of the devastatingly toxic hydroxyl radical resulting in the reduction of oxidative stress. Melatonin's ubiquitous but unequal intracellular distribution, including its high concentrations in mitochondria, likely aid in its capacity to resist oxidative stress and cellular apoptosis. There is credible evidence to suggest that melatonin should be classified as a mitochondria-targeted antioxidant. Melatonin's capacity to prevent oxidative damage and the associated physiological debilitation is well documented in numerous experimental ischemia/reperfusion (hypoxia/reoxygenation) studies especially in the brain (stroke) and in the heart (heart attack). Melatonin, via its antiradical mechanisms, also reduces the toxicity of noxious prescription drugs and of methamphetamine, a drug of abuse. Experimental findings also indicate that melatonin renders treatment-resistant cancers sensitive to various therapeutic agents and may be useful, due to its multiple antioxidant actions, in especially delaying and perhaps treating a variety of age-related diseases and dehumanizing conditions. Melatonin has been effectively used to combat oxidative stress, inflammation and cellular apoptosis and to restore tissue function in a number of human trials; its efficacy supports its more extensive use in a wider variety of human studies. The uncommonly high-safety profile of melatonin also bolsters this conclusion. It is the current feeling of the authors that, in view of the widely diverse beneficial functions that have been reported for melatonin, these may be merely epiphenomena of the more fundamental, yet-to-be identified basic action(s) of this ancient molecule.

Bladder outlet obstruction triggers neural plasticity in sensory pathways and contributes to impaired sensitivity in erectile dysfunction

Lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) are common problems in aging males worldwide. The objective of this work was to evaluate the effects of bladder neck nerve damage induced by partial bladder outlet obstruction (PBOO) on sensory innervation of the corpus cavernosum (CC) and CC smooth muscle (CCSM) using a rat model of PBOO induced by a partial ligation of the bladder neck. Retrograde labeling technique was used to label dorsal root ganglion (DRG) neurons that innervate the urinary bladder and CC. Contractility and relaxation of the CCSM was studied in vitro, and expression of nitric oxide synthase (NOS) was evaluated by Western blotting. Concentration of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide was measured by ELISA. Partial obstruction of the bladder neck caused a significant hypertrophy of the urinary bladders (2.5-fold increase at 2 wk). Analysis of L6-S2 DRG sections determined that sensory ganglia received input from both the urinary bladder and CC with 5-7% of all neurons double labeled from both organs. The contractile responses of CC muscle strips to KCl and phenylephrine were decreased after PBOO, followed by a reduced relaxation response to nitroprusside. A significant decrease in neuronal NOS expression, but not in endothelial NOS or protein kinase G (PKG-1), was detected in the CCSM of the obstructed animals. Additionally, PBOO caused some impairment to sensory nerves as evidenced by a fivefold downregulation of SP in the CC (P ≤ 0.001). Our results provide evidence that PBOO leads to the impairment of bladder neck afferent innervation followed by a decrease in CCSM relaxation, downregulation of nNOS expression, and reduced content of sensory neuropeptides in the CC smooth muscle. These results suggest that nerve damage in PBOO may contribute to LUTS-ED comorbidity and trigger secondary changes in the contraction/relaxation mechanisms of CCSM.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

Small-volume d-β-hydroxybutyrate solution infusion increases survivability of lethal hemorrhagic shock in rats

A small-volume therapeutic approach based on the biochemistry of hibernating mammals was evaluated to test the hypothesis that passive hypothermia and systemic administration of d-β-hydroxybutyrate (d-BHB) plus melatonin will increase survival of animals subjected to hemorrhagic shock ([HS] 60% blood loss). Anesthetized Sprague-Dawley male rats (320 ± 23 g) underwent controlled loss of 60% blood volume. Rats were instrumented to measure mean arterial pressure, body temperature (Tb), and heart rate. A passive decrease in rat Tb in response to HS significantly increased survival over animals maintained at 37°C (n = 5-6). Infusion of 4 M d-BHB, at a volume of only 5.5% of the total blood removed, significantly prolonged survival to a mean of 3 h compared with 90 min using equal osmolar 4 M NaCl (n = 6). In experiments where the shed blood was returned after 1 h of 60% blood loss, 4% fluid replacement with 4 M d-BHB plus 43 mM melatonin significantly prolonged survival up to 10 days after blood return compared with 4 M NaCl plus 43 mM melatonin and other control solutions (n = 10). We conclude that a slow decrease in animal Tb resulting from 60% blood loss, combined with infusion of 4 M d-BHB plus 43 mM melatonin, was beneficial for long-term survival after return of shed blood. This HS therapy is designed as a portable low-volume solution for further evaluation in a large-animal model and is ultimately intended for use in HS patients by first responders.

The role of oxygen-free radical in the apoptosis of enterocytes and bacterial translocation in abdominal compartment syndrome

BACKGROUND

The purpose of this study was to study the impact of intra-abdominal hypertension (IAH) on the intestine.

MATERIALS AND METHODS

One hundred and twenty Sprague-Daley rats were divided into four groups. In the ACS group, the intra-abdominal pressure (IAP) was increased to 20 mmHg. In the ACS/DE group, increased IAP was followed by decompression. In the control1 and control2 groups, the IAP remained unchanged. Malondialdehyde (MDA), myeloperoxidase (MPO), glutathione (GSH) and glutathione peroxidase (GSH-Px) enzymes of the intestine were measured. Additionally, ileal tissues were obtained for histopathological examinations and apoptosis detection. Liver, spleen and mesenteric lymph nodes were obtained for microbiological analysis.

RESULTS

In the presence of IAH, MDA and MPO were increased, while GSH and GSH-Px were decreased. Microbiological analysis suggested bacterial translocation across the gut. Morphological examinations indicated that the Chiu's score and apoptotic index in the ACS/DE group were the highest in the four groups.

CONCLUSIONS

Oxidative stress plays an important role in the intestinal damage and bacterial translocation in abdominal compartment syndrome. Additionally, the influence of oxygen free radicals occurs mainly during the period of reperfusion rather than during the IAH period.

Effects of vitamin E and sodium selenate on impaired contractile activity by bacterial lipopolysaccharide in the rat vas deferens

We investigated whether bacterial lipopolysaccharide (LPS) treatment causes any hyporeactivity in rat vas deferens tissue and also whether vitamin E or sodium selenate has any restorative effect on this possible hyporesponsiveness. LPS treatment attenuated contractions to electrical field stimulation (EFS), phenylephrine, or ATP at the prostatic and epididymal ends. Treatment with the inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine or vitamin E could prevent the impairment in contractile responses of both ends to EFS and phenylephrine but sodium selenate could restore these impaired contractions at only the epididymal end. LPS treatment also caused a similar significantly impairment on purinergic or adrenergic component of nerve-evoked contractions in the presence of prazosin or suramin, respectively, and vitamin E or sodium selenate could restored this impairment at both ends. On the other hand, both antioxidant agents failed to restore the impaired ATP-induced contractions in LPS-treated rats at both ends. In conclusion, LPS-treatment caused a hyporeactivity in the rat vas deferens. A possible increased oxidative activity in the vas deferens may be a major reason for the impairment of contractile responses. The restorative effects of vitamin E and/or sodium selenate on this hypocontractility may depend on their antioxidant properties or their inhibitory action on the iNOS.

Increased corpus cavernosum smooth muscle tone associated with partial bladder outlet obstruction is mediated via Rho-kinase

Numerous studies have now demonstrated that lower urinary tract symptoms (LUTS) are associated with erectile dysfunction (ED) in men independent of age or general health. Because one-third of men over the age of 50 will develop LUTS and a recent study showed ED in 62% of patients presenting for LUTS, the importance of determining the mechanistic link between these two pathologies is clear. Using a rabbit model of partial bladder outlet obstruction (PBOO), a primary cause of LUTS, we have identified an increased basal corpus cavernosum smooth muscle (CCSM) tone associated with an elevated level of smooth muscle myosin (SMM) phosphorylation in PBOO compared with sham-operated control rabbits (sham). Results from in vitro kinase and phosphatase assays using purified smooth muscle myosin showed increased kinase and decreased phosphatase activities in cellular extracts from corpora cavernosa isolated from PBOO compared with sham rabbits. Increased Rho-kinase expression in the CCSM of PBOO rabbits was suggested by the observations that Rho-kinase inhibitors attenuated the increased kinase activity and were less effective in relaxing CCSM strips from PBOO vs. sham rabbits. This hypothesis was then confirmed by RT-PCR and Western blotting, which demonstrated increased expression of both isoforms of Rho-kinase (ROKα and ROKβ). Increased SMM basal phosphorylation (necessary for SM contraction) in the CCSM of PBOO rabbits, mediated via an increase in Rho-kinase expression/activity, would be expected to make the CCSM more difficult to relax (necessary for erection), which suggests that the RhoA/Rho-kinase pathway as being involved in the mechanism for LUTS-associated ED.

Melatonin protects against ionizing radiation-induced oxidative damage in corpus cavernosum and urinary bladder in rats

The objective of this study was to examine the potential radioprotective properties of pharmacological doses of melatonin on corpus cavernosum and bladder tissues of whole-body irradiated (IR) rats. A total of 32 male Sprague-Dawley rats were exposed to irradiation performed with a LINAC which produced 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anesthesia, each rat received a single whole-body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 and 10 mg/kg, i.p.) and decapitated at 12 hr after exposure to irradiation. Another group of rats was followed for 72 hr after IR, where melatonin injections were repeated once daily. Tissue levels of malondialdehyde (MDA), an index of lipid peroxidation, and glutathione (GSH), a key antioxidant, were estimated in corpus cavernosum and urinary bladder. Tissues were also examined microscopically. The results demonstrate that both 12 and 72 hr following IR, tissue levels of MDA were elevated (P < 0.001), while GSH levels were reduced (P < 0.01) in both tissues. On the other hand, melatonin reversed these changes significantly (P < 0.05-0.01), concomitant with the improvement in histological appearances. Our results show that whole-body irradiation causes oxidative damage in the tissues of the genitourinary system. As melatonin administration reversed oxidative organ injury, as assessed by biochemical and histopathological findings, it is suggested that supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy.

Melatonin treatment protects against diabetes-induced functional and biochemical changes in rat aorta and corpus cavernosum

Enhanced oxidative stress due to diabetes is accepted to lead to endothelial dysfunction, and this is known to play a key role in the pathogenesis of diabetic vascular diseases and complications. This study was designed to determine the possible protective effect of melatonin and/or insulin treatment on the functional and biochemical changes caused by hyperglycemia in aorta and corpus cavernosum of diabetic rats. Wistar albino male rats were rendered diabetic by injecting streptozotocin (60 mg/kg, intraperitoneally (i.p.)). Melatonin (10 mg/kg, i.p.) and/or insulin (6 U/kg, subcutaneously (s.c.)) were administered for 8 weeks. In the diabetic group, the contractile responses of aortic strips to phenylephrine were significantly impaired (EC(50) 5.5 x 10(-7) M in diabetic and EC(50) 1.47 x 10(-7) M in the control group, P<0.001). Treatment with melatonin (EC(50) 4.6 x 10(-7) M) or insulin+melatonin (EC(50) 1.68 x 10(-7) M, P<0.001) improved the contractile responses. Acetylcholine caused a dose-dependent relaxation response (EC(50) 1.58 x 10(-7) M) which was impaired in the diabetic group (EC(50) 26 x 10(-7) M, P<0.001). There was less impairment in melatonin-, insulin- and insulin+melatonin-treated groups (EC(50) 11.61 x 10(-7), 7.3 x 10(-7) and 1.41 x 10(-7) M, respectively, P<0.01). Contractile responses to phenylephrine were also impaired in the corpus cavernosum strips (EC(50) 2.06 x 10(-5) M in diabetic and 0.94 x 10(-5) M in the control group, P<0.001). In the melatonin- (EC(50) 1.59 x 10(-5) M) and insulin+melatonin-treated (EC(50) 1.53 x 10(-5) M, P<0.5) groups contractile responses were improved. In the diabetic group, the relaxation responses of corpus cavernosum strips to acetylcholine were impaired (EC(50) 24.12 x 10(-5) M, P<0.001), and treatment with melatonin (EC(50) 0.68 x 10(-5) M), insulin (EC(50) 0.53 x 10(-5) M) or insulin+melatonin (0.98 x 10(-5) M, P<0.001) restored the responses to acetylcholine. In diabetic tissues, malondialdehyde levels were increased while glutathione levels were decreased, demonstrating oxidative damage. This was also prevented by treatment with melatonin or the melatonin and insulin combination. The diabetic state enhances the generation of free radicals, and both melatonin and insulin treatments reduced this oxidative stress; however, treatment with the combination was the most efficient in preventing diabetes-induced damage. Thus, our results suggested that giving diabetic patients adjuvant therapy with melatonin may have some benefit in controlling diabetic complications.

Melatonin ameliorates oxidative organ damage induced by acute intra-abdominal compartment syndrome in rats

Acutely increased intra-abdominal pressure (IAP) can lead to multiple organ failure. As blood flow to intra-abdominal organs is reduced by high venous resistance, ischemia-reperfusion (I/R) injury plays an important role in the pathogenesis of abdominal compartment syndrome (ACS) following IAP. Melatonin, a secretory product of the pineal gland, is known to have free radical scavenging and antioxidative properties in several oxidative processes. The objective of this study was to examine the potential protective properties of melatonin on the oxidative organ damage in a rat model of ACS. Under ketamine anesthesia, an arterial catheter was inserted intraperioneally (i.p.) and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1 hr. In the ischemia/reperfusion (I/R) group, pressure applied for an hour was decompressed and a 1-hr reperfusion period was allowed. In another IR group, melatonin was administered (10 mg/kg, i.p.) immediately before the decompression of IAP. The results demonstrate that tissue levels of malondialdehyde (MDA) and myeloperoxidase activity (MPO; index of tissue neutrophil infiltration) were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in both I and I/R groups (P < 0.05-0.001). Melatonin treatment in I/R rats reversed these changes (P < 0.01-0.001). Moreover, melatonin given to the I/R group reduced the elevations in serum aspartate aminotransferase, alanine aminotransferase and blood urea nitrogen levels and abolished the increase in serum creatinine levels. Our results indicate that melatonin, because of antioxidant and free radical scavenging properties, ameliorates reperfusion-induced oxidative organ damage. In conclusion, the results of the present study suggest that the therapeutic value of melatonin as a 'reperfusion injury-limiting' agent must be considered in ACS.

Octreotide: a new approach to the management of acute abdominal hypertension

Acutely increased intra-abdominal pressure (IAP) may lead to abdominal compartment syndrome (ACS), which ischaemia/reperfusion (I/R) injury plays an important role. The main goal of the management of ACS is to lower the intra-abdominal pressure despite reperfusion injury. Octreotide (OCT), a synthetic somatostatin analogue, lowers the splanchnic perfusion. The aim of this study was to investigate whether OCT improves the reperfusion injury after decompression of acute abdominal hypertension.Under anesthesia, a catheter was inserted intraperitoneally and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1h. In the I/R group, pressure applied for an hour was decompressed and 1h reperfusion period was allowed. In another group of I/R, OCT was administered (50 microg/kg i.p.) immediately before the decompression of IAP. The results demonstrate that kidney and lung tissues of malondialdehyde (MDA; an end product of lipid peroxidation) levels and myeloperoxidase (MPO; index of tissue neutrophil infiltration) activity were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in I/R group (P<0.001). Moreover, OCT treatment applied in the I/R group reduced the elevations in blood urea nitrogen (BUN) and serum creatinine levels. Our results implicate that IAP causes oxidative organ damage and OCT, by reducing splanchnic perfusion and controlling the reperfusion of abdominal organs, could improve the reperfusion-induced oxidative damage. Therefore, its therapeutic role as a "reperfusion injury-limiting" agent must be further elucidated in IAP-induced abdominal organ injury.