Melatonin as a natural anti-inflammatory and anti-oxidant therapy in the testis: a focus on infertility and aging†

Melatonin is a pineal hormone that regulates testicular activity (i.e., steroidogenesis and spermatogenesis) through two complementary mechanisms, indirect effects exerted via the hypothalamic-adenohypophyseal axis and direct actions that take place on the different cell populations of the male gonad. The effects of increased age on the testis and the general mechanisms involved in testicular pathology leading to infertility are still only poorly understood. However, there is growing evidence that link testicular aging and idiopathic male infertility to local inflammatory and oxidative stress events. Because literature data strongly indicate that melatonin exhibits anti-inflammatory and anti-oxidant properties, this review focuses on the potential benefits exerted by this indoleamine at testicular level in male reproductive fertility and aging. Taking into account that the effects of melatonin supplementation on testicular function are currently being investigated, the overview covers not only promising prospects but also many questions concerning the future therapeutic value of this indoleamine as an anti-aging drug as well as in the management of cases of male infertility for which there are no medical treatments currently available.

The effects of pinealectomy and melatonin treatment in acrylamide-induced nephrotoxicity in rats: Antioxidant and anti-inflammatory mechanisms

OBJECTIVE

Acrylamide (AA) is toxic and forms in food that undergoes high-temperature processing. This study aimed to investigate the effects of AA-induced toxicity on renal tissue in pinealectomized rats and the possible protective effect of exogenous Melatonin (ML) administration.

MATERIALS AND METHODS

Sixty rats were randomized into 6 groups (n = 10): Sham, Sham+AA, Sham+AA+ML, PX, PX+AA, and PX+AA+ML. Sham and pinealectomized rats received AA (25 mg/kg/day orally) and ML (0.5 ml volume at 10 mg/kg/day, intraperitoneal) for 21 days.

RESULTS

The results showed that malondialdehyde (MDA), total oxidant status (TOS), oxidative stress index (OSI), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) levels of the kidney and urea and creatinine levels of serum in the PX (pinealectomy)+AA group were more increased than in the Sham+AA group. In addition, glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and total antioxidant status (TAS) levels decreased more in the PX+AA group than in the Sham+AA group. Also, we observed more histopathologic damage in the PX+AA group. On the other hand, up-regulation of kidney tissue antioxidants, down-regulation of tissue oxidants, and improvement in kidney function were achieved with ML treatment. Also, histopathological findings such as inflammatory cell infiltration, shrinkage of glomeruli, and dilatation of tubules caused by AA toxicity improved with ML treatment.

CONCLUSION

ML supplementation exhibited adequate nephroprotective effects against the nephrotoxicity of AA on pinealectomized rat kidney tissue function by balancing the oxidant/antioxidant status and suppressing the release of proinflammatory cytokines.

Protective effects of epigallocatechin gallate in the mice induced by chronic scrotal hyperthermia

One of the most common complications of chronic scrotal hyperthermia (SHT) is a serious disorder in the male reproductive system. The most important factor in the occurrence of these disorders is oxidative stress. Currently, we investigated the effects of epigallocatechin gallate (EGCG), as a highly potent antioxidant, against cells and tissue disorders in mice affected by chronic SHT. Fifty-six male adult NMRI mice were allocated into seven equal groups. Except the non-treated (Control) group, six other groups were exposed to heat stress. Two treated groups including Preventive and Curative received oral administration of EGCG (50 mg/kg/day) starting immediately before heat exposure and fifteen consecutive days after the end of the heat exposure, respectively. For each treated group, two subgroups including positive control (Pre/Cur + PC groups) and vehicle (Pre/Cur + vehicle groups) were considered. At the end of the study, sperm characteristics, testosterone levels, stereological parameters, apoptosis, oxidant state, and molecular assessments were performed. We found that the sperm parameters, testosterone levels, the numerical density of spermatogonia, primary spermatocytes, spermatids, sertoli, leydig cells, and seminiferous tubules, biochemical factors (except MDA), and expression of c-kit gene were significantly higher in the Preventive and Curative groups, especially in Preventive ones, compared to other groups (P < 0.05). This is while expression of HSP72 and NF-κβ genes, MDA levels, as well as density of apoptotic cells considerably decreased in both EGCG-treated groups compared to other groups and it was more pronounced in Preventive ones (P < 0.05). Generally, EGCG attenuated cellular and molecular disorders induced by heat stress in the testis and it was more pronounced in Preventive status.

Impact of gervital against histopathological, ultrastructural, and biochemical alterations caused by methotrexate or azathioprine in albino rat testis

Methotrexate (MTX) and azathioprine (AZA) are chemotherapeutic, immunosuppressive, cytotoxic drugs with reported adverse effects, including oxidative damage to testis. This study aims to evaluate the potential effect of grape seed extract (GSE; gervital) to prevent testicular damage caused by MTX and AZA. Male albino rats were separated into six groups: group I, normal control group; group II, GSE (150 mg/kg/day); group III, MTX (8 mg/kg/week); group IV, AZA (15 mg/kg/day); group V, GSE (150 mg/kg/day) + MTX (8 mg/kg/week); group VI, GSE (150 mg/kg/day) + AZA (15 mg/kg/day). All rats were sacrificed, blood samples were obtained for testosterone analysis, and testis was removed for histological and ultrastructural studies and oxidation measurements. A reduction in relative body and testis weight, along with a significant decrease in testosterone levels, was observed. Histopathological and ultrastructural alterations induced by MTX or AZA included reduced spermatozoa, sloughing, marked reduction of spermatogenic cells, and pyknosis of some nuclei. Significant oxidative stress manifested as reduced glutathione (GSH) levels and catalase (CAT) and superoxide dismutase (SOD) activities, as well as increased malondialdehyde (MDA) levels. GSE administration showed an ameliorative effect on testosterone levels and histopathological and ultrastructural changes. GSE treatment also suppressed the increases in MDA levels and the decreases in GSH levels and CAT and SOD activities. In conclusion, these findings confirm that GSE is an effective antioxidant that protects testis from histopathological and ultrastructural damage induced by MTX and AZA. Therefore, GSE is a promising candidate for future use to minimize and alleviate MTX and AZA risks.

Oxidative-antioxidative status and hepatic and renal factors following melatonin administration in castrated and intact dogs

Backgrounds

Melatonin has significant antioxidant and hepatoprotective effects in normal and oxidative stress conditions. The aim of the present study was to assess the effects of melatonin on antioxidant, hepatic, and renal factors in intact and castrated dogs. Twenty male mixed-breed adult dogs were aligned in an experimental randomized and controlled trial. The dogs were randomly divided into four equal groups: melatonin, castrated, castrated and melatonin, and control. They were treated with melatonin (0.3 mg/Kg, once daily, orally) immediately after the castration for 1 month and their blood samples were collected weekly from 2 days after treatment with melatonin.

Results

Treating castrated dogs with melatonin increased the level of glutathione peroxidase, superoxide dismutase, and catalase compared with that of the control and castrated groups. The malondialdehyde level increased significantly following castration. Melatonin treatment decreased malondialdehyde concentration in the castrated dogs. Castration increased the level of alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase significantly in comparison with that of the control group. Treating the castrated dogs with melatonin decreased significantly liver enzymes compared with those of the castrated dogs. Blood urea nitrogen and creatinine levels increased in the castrated dogs in comparison with that of the control group.

Conclusions

The administration of melatonin in castrated dogs increased antioxidant activity and decreased oxidation products, compared with those of the castrated and untreated dogs, without adverse effects on liver enzymes and kidney function.

Protective and therapeutic effects of dexpanthenol on isoproterenol-induced cardiac damage in rats

The purpose of the study was to explore the protective and therapeutic effects of dexpanthenol (DEX) on isoproterenol (ISO)-induced cardiac damage. Forty rats were distributed into four groups: group I (Control); group II (ISO); ISO (150 mg/kg/day) was given to rats once a day for 2 consecutive days with an interval of 24 h; group III (DEX+ISO): DEX (250 mg/kg) was applied 30 min before the first ISO administration and continued in the next two days after second ISO administration; group IV (ISO+DEX): After the ISO treatment at 1st and 2nd days, DEX was given at 3rd and 4th days. Rats were monitored for mean arterial blood pressure (BP), heart rate, oxygen saturation (%SO₂ ), and electrocardiography (ECG). Heart tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), reduced glutathione (GSH), total oxidant status (TOS); total antioxidant capacity (TAC), oxidative stress index (OSI), and caspase-3 were determined. BP and SO₂ values indicated a significant decrease in the ISO group. Also, T wave negativity was observed in 6 of 10 rats, SOD, CAT, and GPX levels were significantly lower in ISO group than control group. ISO administration increased TOS and OSI levels, whereas DEX treatment significantly reduced these parameters. Also, ISO-induced morphological alterations such as disorganization of cardiomyocytes, loss of myofibrils and cytoplasmic vacuolization whereas these histological damages were significantly decreased in ISO+DEX and DEX+ISO groups when compared to the ISO group. This study implies the cardioprotective effects of DEX on ISO-induced cardiotoxicity.

Protective antioxidative effects of caffeic acid phenethyl ester (CAPE) in the thyroid and the liver are similar to those caused by melatonin

Background

Whereas oxidative reactions occur in all tissues and organs, the thyroid constitutes such an organ, in which oxidative processes are indispensable for physiological functions. In turn, numerous metabolic reactions occurring in the liver create favourable conditions for huge oxidative stress. Melatonin is a well-known antioxidant with protective effects against oxidative damage perfectly documented in many tissues, the thyroid and the liver included. Caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, has been suggested to be also an effective antioxidant.

The aim of the study was to evaluate the effects of CAPE on Fenton reaction-induced oxidative damage to membrane lipids (lipid peroxidation, LPO) in porcine thyroid and liver, and to compare the results with protective effects of melatonin.

Methods

Thyroid and liver homogenates were incubated in the presence of CAPE (500; 100; 50; 10; 5.0; 1.0 μM) or melatonin (500; 100; 50; 10; 5.0; 1.0 μM), without or with addition of FeSO₄ (30 μM) + H₂O₂ (0.5 mM).

The level of lipid peroxidation was measured spectrophotometrically and expressed as the amount of MDA + 4-HDA (nmol) per mg of protein.

Results

Whereas CAPE decreased the basal LPO in a concentration-dependent manner in both tissues, melatonin did not change the basal LPO level. When antioxidants were used together with Fenton reaction substrates, they prevented – in a concentration-dependent manner and to a similar extent – experimentally-induced LPO in both tissues.

Conclusions

Protective antioxidative effects of CAPE in the thyroid and the liver are similar to those caused by melatonin. CAPE constitutes a promising agent in terms of its application in experimental and, possibly, clinical studies.