Enhancing fentanyl antinociception and preventing tolerance with α-2 adrenoceptor agonists in rats

Fentanyl (FEN) is a potent opioid analgesic used for pain management. Opioid analgesic tolerance poses a significant challenge to the clinical utility of opioid agonists. Preventing the development of tolerance to opioid analgesia is crucial for improving its efficacy and safety. The noradrenergic system is involved in pain regulation. This study examined the effects of α-2 adrenoceptor (AR) agonists, dexmedetomidine (DEX), and xylazine (XYL) on FEN tolerance and antinociception, and their impact on μ-opioid receptor (MOR) expression in the posterior horn of the spinal cord (SC). Male rats were divided into six groups and treated with different drug combinations for three consecutive days. Analgesia tests and motor performance assessments were conducted, followed by SC analysis using immunohistochemistry (IHC). Analgesia tests revealed the development of FEN tolerance on the second day, but the groups receiving combined drugs did not develop tolerance. Instead, FEN antinociception was enhanced, with a prolonged duration of its effects. None of the drugs caused sedation or motor impairment, and SC morphology appeared normal. MOR expression levels did not differ significantly between the groups based on IHC analysis. These findings suggest that changes in the secondary messenger system may play a role in the early development of FEN tolerance. Combining drugs can prevent tolerance, while enhancing FEN's antinociceptive effects. These results have promising implications for chronic pain management; however, further research is needed to explore the molecular effects of α-2 AR agonists on FEN tolerance. Overall, this study sheds light on the mechanism of FEN tolerance and identifies potential avenues for future research.

Effects of intracerebroventricular and intravenous administration of Kisspeptin-54 and Gonadotropin-releasing hormone agonist in rats with ovarian hyperstimulation

PURPOSE

We aim to determine the effect of local and systemic administration of kisspeptin-54 on ovarian hyperstimulation.

METHODS

Immature female rats were used. In order to generate the ovarian hyperstimulation model, 50 IU PMSG was administered for 4 consecutive days and a single dose of 25 IU hCG was administered to all groups except for the sham group. To synchronize the sham group, a single dose of 10 IU PMSG followed by 10 IU hCG (48 h later) was applied. Kisspeptin-54 and gonadotropin-releasing hormone (GnRH) agonists were administered 48 h after hCG injection. While intracerebroventricular injection is performed with stereotaxic surgery, Intravenous administration was from the tail vein. Ovarian weights were measured. FSH, LH, estrogen and progesterone hormones were detected in serum by ELISA. VEGFa, IL-1β, TNF-α, MCP-1 immunohistochemical staining was performed on the ovaries and hypothalamus and their optical densities were determined with Image J. Kiss1R mRNA expression was determined by qRT-PCR.

RESULTS

Ovarian weights increased significantly in the OHSS group and the systemic GnRH agonist group. The optical densities of VEGFa, IL-1β, TNF- α and MCP-1 immunoreactivity showed us that both local and systemic applied kisspeptin-54 attenuates the level of investigated inflammation parameters in the ovaries. Moreover, local administration of kisspeptin-54 has been shown to enhance the level of Kiss1R mRNA in both the ovaries and the hypothalamus.

CONCLUSION(S)

Local and systemic administration of Kisspeptin-54 as a post-treatment reduces inflammation parameters in the ovaries. These findings promote the potential use of kisspeptin-54 on OHSS.

The effects of chronic restraint stress on empathy-like behaviour in rats

It is clearly known that psychological stress is an important threat to health in today's modern societies. Recent studies have shown that acute stress causes an increase in positive social behaviours such as prosocial behaviour and devotion which are components of empathic behaviour. Neuropsychiatric manifestations such as anxiety and depression may affect empathic behaviour. The aim of this study was to investigate the effects of chronic restraint stress on empathy-like behaviour and the histopathological changes in the amygdala, prefrontal cortex in the adrenal glands and thymus, as well as the neurochemical pathways associated with empathy, oxytocin and vasopressin. The chronic stress group was subjected to restraint stress daily for 14 days after all subjects were trained to rescue its stressed cagemate using empathy test equipment for 12 days. It was observed that chronic restraint stress had no effect on empathy-like behaviour in rats. Vasopressin levels in amygdala was increased in chronic stress group compared to control group. Anxiety and depression indicators did not change in both groups. In the open field test, control group spent more time in thigmo zone compared to chronic stress group. Adrenal glands relative weights and apoptotic cell ratios were significantly higher in the chronic stress group compared to the control group (expectedly). Although there was no significant difference in behavioral tests, histopathological changes were detected. In subsequent studies, it is appropriate to examine the effects of different types of stress applications, gender-related changes, and other neurochemical pathways associated with stress and empathy.

No effects of 900 MHz and 1800 MHz electromagnetic field emitted from cellular phone on nocturnal serum melatonin levels in rats

In this study, the effects of exposure to a 900 MHz and 1800 MHz electromagnetic field (EMF) on serum nocturnal melatonin levels of adult male Sprague-Dawley rats were studied. Thirty rats were used in three independent groups, 10 of which were exposed to 900 MHz, 10 of which were exposed to 1800 MHz and 10 of which were sham-exposed (control). The exposures were performed 30 min/day, for five days/week for four weeks to 900 MHz or 1800 MHz EMF. Control animals were kept under the same environmental conditions as the study groups except with no EMF exposure. The concentration of nocturnal melatonin in the rat serum was measured by using a radioimmunoassay method. There were no statistically significant differences in serum melatonin concentrations between the 900 MHz EMF group and the sham-exposed group (P-0.05). The values at 12:00 pm were 39.119 / 6.5 pg/mL in the sham-exposed group and 34.979 / 5.1 pg/mL in the 900 MHz EMF-exposed group. Also, there were no statistically significant differences in serum melatonin concentrations between the sham-exposed group and the 1800 MHz EMF-exposed group (P-0.05). The values at 12:00 pm were 39.119 / 6.5 pg/mL in the sham-exposed group and 37.969 / 7.4 pg/mL in the exposed group. These results indicate that mobile phones, emitting 900 and 1800 MHz EMF, have no effect on nocturnal serum melatonin levels in rats.

Prevention of mobile phone induced skin tissue changes by melatonin in rat: an experimental study

Most of the mobile phones in Turkey emit 900 MHz radiation which is mainly absorbed by the skin and, to a lesser extent, muscle. The aim of this study was to investigate the effects the 900 MHz electromagnetic irradiation emitted by these devices on the induction of histopathologic changes in skin and the effect of melatonin (Mel) on any of these changes. Thirty male Wistar-Albino rats were used in the study. The experimental groups were composed of: a nontreated control group, an irradiated group (IR) without Mel and an irradiated with Mel treatment group (IR + Mel). 900 MHz radiation was applied to IR group for 10 days (30 min/day). The IR + Mel group received 10 mg/kg per day melatonin in tap water for 10 days before irradiation. At the end of the tenth day, the skin graft was excized from the thoraco-abdominal area. Histopathologic changes in skin were analyzed. In the IR group, increased thickness of stratum corneum, atrophy of epidermis, papillamatosis, basal cell proliferation, increased granular cell layer (hypergranulosis) in epidermis and capillary proliferation, impairment in collagen tissue distribution and separation of collagen bundles in dermis were all observed compared to the control group. Most of these changes, except hypergranulosis, were prevented with melatonin treatment. In conclusion, exposure to 900 MHz radiation emitted by mobile phones caused mild skin changes. Furthermore, melatonin treatment can reduce these changes and may have a beneficial effect to prevent 900 MHz mobile phone-induced rat skin changes.

Impact of caffeic acid phenethyl ester treatment on vancomycin-induced pancreatic damage in rats

This study investigates the preventive effect of caffeic acid phenethyl ester (CAPE) on pancreatic damage induced by vancomycin (VCM) in rats. Rats were equally divided into three groups: group I (control), group II (only VCM-treated group) and group III (VCM + CAPE-treated groups). VCM was intraperitoneally administered at a dose of 200 mg kg(-1)twice daily for 7 days. CAPE was administered orally at 10 µM mL(-1) kg(-1) dose once daily for 7 days. The first dose of CAPE administration was performed 24 h prior to VCM injection. Blood and pancreas tissue samples were removed and collected after the study. Serum alkaline phosphatase (ALP), amylase, γ-glutamyl transferase (GGT) and lipase activities were determined. Pancreas tissue samples were evaluated with the light microscope. Group II significantly increased serum ALP, amylase, GGT and lipase activities when compared with the control group. Group III significantly decreased serum ALP, amylase, GGT and lipase activities when compared with group II. In histopathological examination, it has been observed that there was a significant pancreatic damage in group II. CAPE exerted prominent structural protection against VCM-induced pancreatic damage and this effect was statistically significant. CAPE caused a marked reduction in the extent of pancreatic damage. We have concluded that it may play an important role in the VCM-induced pancreatic damage and reduce the pancreatic damage both at the biochemical and histopathological aspects.

Investigating the effectiveness of different tea types from various thyme kinds (Origanum onites, Thymbra spicata and Satureja cuneifolia) on anemia and anticholesterolemic activity

In a study on villagers settled on the outskirts of the Taurus Mountains and whose source of living is thyme, it was revealed that the villagers excessively consumed thyme by adding it to their tea and many of their foods; high incidences of anemia was found among these villagers. In this study, 42 male adult Wistar albino rats weighing 200–250 g were used. The rats were divided to six equal groups as follows: control, cholesterol (Chol), 80 mg/kg Origanum onites Labiatae (OOL), 80 mg/kg Thymbra spicata Labiatae (TSL), 80 mg/kg Satureja cuneifolia Labiatae (SCL), and 160 mg/kg TSL, and each group consisted of seven rats. The control group was fed with normal pellet feed. The Chol group and all the other groups, except for the control group, were fed with 2% cholesterol-containing pellet feed. Physiological serum of 4 ml was given to the control and Chol group, wheile 80 mg/kg of thymes tea was given to the OOL group, TSL group, and SCL group, and 160 mg/kg of thymes tea was given to the TSL group by means of a gavage for 30 days. In the blood samples, the hematologic parameters and the biochemical parameters of serum glucose, blood urea nitrogen, creatinine, total protein, albumin, iron (I), total iron-binding capacity, aminotransferase aspartate, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein cholesterol, triglyceride, and oxidized LDL levels were examined. The kidney and liver tissues were examined histopathologically. The results of the study showed that different types of thymes had an antihypercholesterolemic effect. In addition to the anemic effect detected in group TSL and the mild granular degeneration found in the liver of 80 mg/kg SCL group, distinct granular degeneration was observed in 160 mg/kg TSL group.

Testicular apoptosis and histopathological changes induced by a 2.45 GHz electromagnetic field

There is a growing public concern about the potential human health hazard caused by exposure to electromagnetic radiation (EMR). The objective of this study is to investigate the effects of 2450 mhz electromagnetic field on apoptosis and histopathological changes on rat testis tissue. Twelve-week-old male Wistar Albino rats were used in this study. Eighteen rats equally divided into three different groups which were named group I, II and III. Cage control (group I), sham control (group II) and 2.45 GHz EMR (group III) groups were formed. Group III were exposed to 2.45 GHz EMR, at 3.21 W/kg specific absorption rate for 60 minutes/ day for 28 days. There was no difference among the groups for the diameter of the seminiferous tubules, pyknotic, karyolectic and karyotic cells. However, the number of Leydig cells of testis tissue of the rats in group III was significantly reduced comparing with the group I (p < 0.05). Estimation of spermatogenesis using the Johnsen testicular biopsy score revealed that the difference between groups is statistically significant. The level of TNF-α, Caspase-3 and Bcl-2 were compared, and no significant difference was found between the groups. When Bax apoptosis genes and Caspase-8 apoptosis enzyme were compared, there were significant differences between the groups (p < 0.05). Electromagnetic field affects spermatogenesis and causes to apoptosis due to the heat and other stress-related events in testis tissue.

N-acetylcysteine modulates doxorubicin-induced oxidative stress and antioxidant vitamin concentrations in liver of rats

Doxorubicin (DOX) is a chemotherapeutic agent, and is widely used in cancer treatment. The most common side effect of DOX was indicated on cardiovascular system by experimental studies. There are some studies suggesting oxidative stress-induced toxic changes on liver related to DOX administration. The aim of the present study was to evaluate whether antioxidant N-acetylcysteine (NAC) relieves oxidative stress in DOX- induced liver injury in rat. Twenty-four male rats were equally divided into three groups. First group was used as a control. Second group received single dose of DOX. NAC for 10 days was given to constituting the third group after giving one dose of DOX. After 10 days of the experiment, liver tissues were taken from all animals. Lipid peroxidation (LP) levels were higher in the DOX group than in control whereas LP levels were lower in the DOX+NAC group than in control. Vitamin C and vitamin E levels were lower in the DOX group than in control whereas vitamin C and vitamin E levels were higher in the DOX+NAC group than in the DOX group. Reduced glutathione levels were higher in the DOX+NAC group than in control and DOX group. Glutathione peroxidase, vitamin A and β-carotene values were not changed in the three groups by DOX and NAC administrations. In histopathological evaluation of DOX group, there were mononuclear cell infiltrations, vacuolar degeneration, hepatocytes with basophilic nucleus and sinusoidal dilatations. The findings were totally recovered by NAC administration. In conclusion, N-acetylcysteine induced modulator effects on the doxorubicin-induced hepatoxicity by inhibiting free radical production and supporting the antioxidant vitamin levels.

Effects of selenium and L-carnitine on oxidative stress in blood of rat induced by 2.45-GHz radiation from wireless devices

The levels of blood lipid peroxidation, glutathione peroxidase, reduced glutathione, and vitamin C were used to follow the level of oxidative damage caused by 2.45 GHz electromagnetic radiation in rats. The possible protective effects of selenium and L-carnitine were also tested and compared to untreated controls. Thirty male Wistar Albino rats were equally divided into five groups, namely Groups A1 and A2: controls and sham controls, respectively; Group B: EMR; Group C: EMR + selenium, Group D: EMR + L-carnitine. Groups B–D were exposed to 2.45 GHz electromagnetic radiation during 60 min/ day for 28 days. The lipid peroxidation levels in plasma and erythrocytes were significantly higher in group B than in groups A1 and A2 (p<0.05), although the reduced glutathione and glutathione peroxidase values were slightly lower in erythrocytes of group B compared to groups A1 and A2. The plasma lipid peroxidation level in group A2 was significantly lower than in group B (p<0.05). Erythrocyte reduced glutathione levels (p<0.01) in group B; erythrocyte glutathione peroxidase activity in group A2 (p<0.05), group B (p<0.001), and group C (p<0.05) were found to be lower than in group D. In conclusion, 2.45 GHz electromagnetic radiation caused oxidative stress in blood of rat. L-carnitine seems to have protective effects on the 2.45-GHz-induced blood toxicity by inhibiting free radical supporting antioxidant redox system although selenium has no effect on the investigated values.

The protective effect of caffeic acid phenethyl ester (CAPE) on oxidative stress in rat liver exposed to the 900 MHz electromagnetic field

In this study, we aimed to investigate the possible protective effects of caffeic acid phenethyl ester (CAPE) on lipid peroxidation (LPO) and the activities of antioxidant enzymes in the liver of rats exposed to the 900 MHz electromagnetic field (EMF). EMF of cellular phones may affect biological systems by increasing free radical, which appear mainly to enhance LPO, and by changing the antioxidative activities of liver, thus leading to oxidative damage. CAPE, an active component of propolis extract, exhibits antioxidant properties and several studies suggest that supplementation with antioxidant can influence EMF exposure induced hepatotoxicity. Thirty male Sprague-Dawley rats were divided into three groups: control ( n = 10), 900 MHz EMF ( n = 10) and 900 MHz EMF + CAPE ( n = 10). CAPE was injected intraperitoneally for 30 days before exposure to EMF. Liver tissue was removed to study the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), xanthine oxidase (XO) and the levels of LPO. The activities of XO, CAT and level of LPO increased in the 900 MHz electromagnetic field (EMF) group compared with the control group, although XO, CAT activities and LPO levels were decreased by 900 MHz EMF + CAPE administration. The activities of SOD and GSH-Px decreased in the 900 MHz EMF group compared with the control group, although their levels were increased by EMF + CAPE administration. It can be concluded that CAPE may prevent the 900 MHz EMF-induced oxidative changes in liver by strengthening the antioxidant defense system by reducing reactive oxygen species and increasing antioxidant enzyme activities.

Influence of Electromagnetic Fields and Protective Effect of CAPE on Bone Mineral Density in Rats

BACKGROUND

Most mobile phones emit electromagnetic radiation at 900 MHz or 1800 MHz. An electromagnetic field has some biological effects on the behavior of the cell population of bone. The aim of this work is to evaluate the effects of the radiation emitted by mobile phones on bone mineral density (BMD). The effects of caffeic acid phenethyl ester (CAPE) on the radiation-induced changes were also investigated.

METHODS

In the study, 48 Sprague Dawley rats were used. Rats were divided into five groups as follows: control, irradiated with 900 MHz, irradiated with 900 MHz and treatment, irradiated with 1800 MHz, irradiated with 1800 MHz and treatment groups. The rats in the control group (first group) were left within the experimental setup during 30 min/day for 28 days without radiation exposure. Nine hundred-MHz radiation group was exposed to irradiate both second and third groups for 28 days (30 min/day); 1800-MHz radiation group was exposed to irradiate both fourth and fifth groups for 28 days (30 min/day). Third and fifth groups were also treated by CAPE for 28 days. Treatment groups received 10 microml/kg/day CAPE i.p. before the irradiation. Bone mineral densities were determined in all groups.

RESULTS

BMD was found to be decreased in the irradiated groups and to be increased in the treatment groups.

CONCLUSIONS

The changes were not significant (p >0.05).

Preventive effect of vitamin E on iron-induced oxidative damage in rabbit

Although iron (Fe), plays an important role in different oxidative steps during the metabolism of the human body, it can cause free radical damage. Iron ions seem to play a major role in initiation and promotion reactions of intracellular lipid peroxidation. The aim of this study was to investigate if vitamin E has a protective effect on oxidative changes in erythrocytes induced by Fe treatment. Thirty male New Zealand white rabbits weighing 1400 +/- 50 g were used in the study. The animals were divided into three groups. The first group (n:10) was given 500 mg/kg iron-dextran through intraperitoneal (ip) injection. The second group was given 500 mg/kg iron-dextran+100 mg/kg vitamin E(ip). The third group constituted the control group and received a saline solution injection. The activities of erythrocyte antioxidant enzymes; Superoxide Dismutase (SOD), Glutatione peroxidase (GSH-Px), Catalase (CAT) and Malondialdehyde (MDA) level, an indicator of lipid peroxidation, were determined. Erythrocyte SOD, GSH-Px and CAT activities were decreased and MDA level was increased in iron-dextran treated animals compared to the control group (P < 0.05). The activities of the three antioxidant enzymes were increased and MDA level was decreased in iron-dextran and vitamin E treated group compared to the control group (P < 0.05). Our data indicate that lipid peroxidation occurs after iron overload in the blood. In the light of our findings, vitamin E administration can prevent the toxic oxidative effects induced by iron-dependent free radical damage in erythrocytes.

Evaluation of the effects of cadmium on rat liver

Cadmium is one of the most toxic pollutants in environment. Cadmium accumulation in blood affects the renal cortex and causes renal failure. In this study, we aimed to evaluate the effects of cadmium on rat liver tissue. Eighteen male albino rats aged ten weeks old were used in the study. 15 ppm of cadmium was administered to rats via consumption water daily. At the end of the 30th study day, the animals were killed under ether anesthesia. After the liver tissue samples were taken, histopathological and biochemical examinations were performed. Histopathologic changes have included vacuolar and granular degenerations in hepatocytes, heterochromatic nucleuses and sinusoidal and portal widenings. Central vein diameters were normal in cadmium exposed group. Whereas, there was statistically significant difference between two groups by means of sinusoidal (p< 0.001) and portal triad diameters (p< 0.01). Malondialdehyde (MDA) is an indicator of lipid peroxidation. In this study, MDA was used as a marker of oxidative stress-induced liver impairment in cadmium exposed rats. Superoxide dismutase (SOD) and catalase (CAT) activities were also measured to evaluate the changes in antioxidative system in liver tissues. Current findings showed that MDA levels were increased and SOD and CAT activities were decreased in cadmium exposed group compared to control group. The difference between two groups was statistically significant (pvalues: MDA,p< 0.01; CAT,p< 0.01 and SOD,p< 0.05). In conclusion, these findings suggest the role of oxidative mechanisms in cadmium-induced liver tissue damage.

Active smoking causes oxidative stress and decreases blood melatonin levels

Oxidative effects via free radical generation in smokers have been widely investigated. They cause lipid peroxidation, oxidation of proteins and damage to mainly lung and other tissues. In humans, antioxidative capacity of serum is related to antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and melatonin. The effect of cigarette smoking on plasma levels of melatonin and antioxidant enzymes has not been established together yet. Also, it may not be clear if melatonin levels are affected by smoking and melatonin has a protective effect on cigarette smoking-induced free radical damage. The aim of this study is to investigate the relationship between smoking and antioxidant capacity including melatonin, a powerful endogenous antioxidant, and antioxidant enzymes in teenage girls who are active smokers. Additionally, malondialdehyde (MDA) levels were determined in those who have smoked at least one packet a day for three or more years. MDA levels have been used as a convenient index of the lipid peroxidation-related oxidative damage of tissues. Twenty-one young female active smokers who study at the School of Nursing and 21 nonsmoking students (as controls) at the same school were included in the study. The activities of two principal antioxidant enzymes SOD, GSH-Px and plasma levels of MDA were significantly increased but melatonin content of the blood was significantly decreased as compared to nonsmokers. In spite of an increase in antioxidant enzyme activities, MDA levels were slightly increased in smokers. This indicates that antioxidant self-defence mechanisms may not sufficiently protect the respiratory system from smoke-mediated oxidative injury. This result may be related to low melatonin levels in teenage female smokers. It seems that melatonin can reduce free radical damage to the respiratory system induced by cigarette smoke. Further experimental investigations with exogenous melatonin treatments will be needed.

A novel antioxidant agent caffeic acid phenethyl ester prevents long-term mobile phone exposure-induced renal impairment in rat

Caffeic acid phenethyl ester (CAPE), a flavonoid like compound, is one of the major components of honeybee propolis. It has been used in folk medicine for many years in Middle East countries. It was found to be a potent free radical scavenger and antioxidant recently. The aim of this study was to examine long-term applied 900 MHz emitting mobile phone-induced oxidative stress that promotes production of reactive oxygen species (ROS) and, was to investigate the role of CAPE on kidney tissue against the possible electromagnetic radiation (EMR)-induced renal impairment in rats. In particular, the ROS such as superoxide and nitric oxide (NO) may contribute to the pathophysiology of EMR-induced renal impairment. Malondialdehyde (MDA, an index of lipid peroxidation) levels, urinary N-acetyl-beta-D-glucosaminidase (NAG, a marker of renal tubular injury) and nitric oxide (NO, an oxidant product) levels were used as markers of oxidative stress-induced renal impairment and the success of CAPE treatment. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in renal tissue were determined to evaluate the changes of antioxidant status. The rats used in the study were randomly grouped (10 each) as follows: i) Control group (without stress and EMR), ii) Sham-operated rats stayed without exposure to EMR (exposure device off), iii) Rats exposed to 900 MHz EMR (EMR group), and iv) A 900 MHz EMR exposed + CAPE treated group (EMR + CAPE group). In the EMR exposed group, while tissue MDA, NO levels and urinary NAG levels increased (p < 0.0001), the activities of SOD, CAT, and GSH-Px in renal tissue were reduced (p < 0.001). CAPE treatment reversed these effects as well (p < 0.0001, p < 0.001 respectively). In conclusion, the increase in NO and MDA levels of renal tissue, and in urinary NAG with the decrease in renal SOD, CAT, GSH-Px activities demonstrate the role of oxidative mechanisms in 900 MHz mobile phone-induced renal tissue damage, and CAPE, via its free radical scavenging and antioxidant properties, ameliorates oxidative renal damage. These results strongly suggest that CAPE exhibits a protective effect on mobile phone-induced and free radical mediated oxidative renal impairment in rats.

Comparative analysis of the protective effects of melatonin and caffeic acid phenethyl ester (CAPE) on mobile phone-induced renal impairment in rat

Melatonin and caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, were recently found to be potent free radical scavengers and antioxidants. There are a number of reports on the effects induced by electromagnetic radiation (EMR) in various cellular systems. Mechanisms of adverse effects of EMR indicate that reactive oxygen species may play a role in the biological effects of this radiation. The present study was carried out to compare the protective effects of melatonin and CAPE against 900 MHz EMR emitted mobile phone-induced renal tubular injury. Melatonin was administered whereas CAPE was given for 10 days before the exposure. Urinary N-acetyl-beta-D-glucosaminidase (NAG, a marker of renal tubular injury) and malondialdehyde (MDA, an index of lipid peroxidation), were used as markers of oxidative stress-induced renal impairment in rats exposed to EMR. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status in renal tissue. Urinary NAG and renal MDA were increased in EMR exposed rats while both melatonin and CAPE caused a significant reduction in the levels of these parameters. Likewise, renal SOD and GSH-Px activities were decreased in EMR exposed animals while melatonin caused a significant increase in the activities of these antioxidant enzymes but CAPE did not. Melatonin caused a significant decrease in urinary NAG activity and MDA levels which were increased because of EMR exposure. CAPE also reduced elevated MDA levels in EMR exposed renal tissue, but the effect of melatonin was more potent than that of CAPE. Furthermore, treatment of EMR exposed rats with melatonin increased activities of SOD and GSH-Px to higher levels than those of control rats. In conclusion, melatonin and CAPE prevent renal tubular injury by reducing oxidative stress and protect the kidney from oxidative damage induced by 900 MHz mobile phone. Nevertheless, melatonin seems to be a more potent antioxidant compared with CAPE in kidney.

Effects of 900 MHz electromagnetic field on TSH and thyroid hormones in rats

In this study, the effects of exposure to a 900 megahertz (MHz) electromagnetic field (EMF) on serum thyroid stimulating hormone (TSH) and triiodothronine-thyroxin (T3-T4) hormones levels of adult male Sprague-Dawley rats were studied. Thirty rats were used in three independent groups, 10 of which were control (without stress and EMF), 10 of which were exposed to 900 MHz EMF and 10 of which were sham-exposed. The exposures were performed 30 min/day, for 5 days/week for 4 weeks to 900 MHz EMF. Sham-exposed animals were kept under the same environmental conditions as the study groups except with no EMF exposure. The concentration of TSH and T3-T4 hormones in the rat serum was measured by using an immunoradiometric assay (IRMA) method for TSH and a radio-immunoassay (RIA) method for T3 and T4 hormones. TSH values and T3-T4 at the 900 MHz EMF group were significantly lower than the sham-exposed group (p<0.01). There were no statistically significant differences in serum TSH values and T3-T4 hormone concentrations between the control and the sham-exposed group (p>0.05). These results indicate that 900 MHz EMF emitted by cellular telephones decrease serum TSH and T3-T4 levels.

Oxidative Damage in the Kidney Induced by 900-MHz-Emitted Mobile Phone: Protection by Melatonin

BACKGROUND

The mobile phones emitting 900-MHz electromagnetic radiation (EMR) may be mainly absorbed by kidneys because they are often carried in belts. Melatonin, the chief secretory product of the pineal gland, was recently found to be a potent free radical scavenger and antioxidant. The aim of this study was to examine 900-MHz mobile phone-induced oxidative stress that promotes production of reactive oxygen species (ROS) on renal tubular damage and the role of melatonin on kidney tissue against possible oxidative damage in rats.

METHODS

The animals were randomly grouped as follows: 1) sham-operated control group and 2) study groups: i) 900-MHz EMR exposed (30 min/day for 10 days) group and ii) 900-MHz EMR exposed+melatonin (100 microg kg(-1) s.c. before the daily EMR exposure) treated group. Malondialdehyde (MDA), an index of lipid peroxidation), and urine N-acetyl-beta-d-glucosaminidase (NAG), a marker of renal tubular damage were used as markers of oxidative stress-induced renal impairment. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status.

RESULTS

In the EMR-exposed group, while tissue MDA and urine NAG levels increased, SOD, CAT, and GSH-Px activities were reduced. Melatonin treatment reversed these effects as well. In this study, the increase in MDA levels of renal tissue and in urine NAG and also the decrease in renal SOD, CAT, GSH-Px activities demonstrated the role of oxidative mechanism induced by 900-MHz mobile phone exposure, and melatonin, via its free radical scavenging and antioxidant properties, ameliorated oxidative tissue injury in rat kidney.

CONCLUSIONS

These results show that melatonin may exhibit a protective effect on mobile phone-induced renal impairment in rats.

A novel antioxidant agent caffeic acid phenethyl ester prevents shock wave-induced renal tubular oxidative stress

The aim of this study was to evaluate the effects of the novel free radical scavenger caffeic acid phenethyl ester (CAPE) on extracorporeal shock wave lithotripsy (ESWL) induced renal impairment. The study was performed using 30 rabbits which were divided into two groups, each exposed to 3,000 shock waves at 18 kV: (1) control group, (2) ESWL+CAPE treated group. Malodialdehyde (MDA), urine N-acetyl-beta-glucosaminidase (NAG) activity, uric acid and white cell counts were used as markers of oxidative stress. Following shock wave exposure there was a significant rise in MDA, NAG and uric acid and white cell counts. CAPE reduced the rise in MDA, NAG, uric acid and white cell counts. Thus CAPE treatment to a great extent prevented the induction of these renal changes. Our results suggest that the antioxidant capacity of the kidney tissue was reduced after ESWL treatment and that the tissue was exposed to oxidant stress. We conclude that CAPE treatment provided significant protection against ESWL induced free radical damage.

Biological and morphological effects on the reproductive organ of rats after exposure to electromagnetic field

OBJECTIVE

The biological effect of electromagnetic field (EMF) emitted from mobile phones is a current debate and still a controversial issue. Therefore, little is known on the possible adverse effects on reproduction as mobile phone bio-effects are only a very recent concern. The aim of this experimental study was to determine the biological and morphological effects of 900 MHz radiofrequency (RF) EMF on rat testes.

METHODS

The study was performed in the Physiology and Histology Research Laboratories of Süleyman Demirel University, Faculty of Medicine, Isparta, Turkey in May 2004. Twenty adult male Sprague-Dawley rats weighing 270-320 gm were randomized into 2 groups of 10 animals: Group I (control group) was not exposed to EMF and Group II (EMF group) was exposed to 30 minutes per day, 5 days a week for 4 weeks to 900 MHz EMF. Testes tissues were submitted for histologic and morphologic examination. Testicular biopsy score count and the percentage of interstitial tissue to the entire testicular tissue were registered. Serum testosterone, plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels were assayed biochemically.

RESULTS

The weight of testes, testicular biopsy score count and the percentage of interstitial tissue to the entire testicular tissue were not significantly different in EMF group compared to the control group. However, the diameter of the seminiferous tubules and the mean height of the germinal epithelium were significantly decreased in EMF group (p<0.05). There was a significant decrease in serum total testosterone level in EMF group (p<0.05). Therefore, there was an insignificant decrease in plasma LH and FSH levels in EMF group compared to the control group (p>0.05).

CONCLUSION

The biological and morphological effects resulting from 900 MHz RF EMF exposure lends no support to suggestions of adverse effect on spermatogenesis, and on germinal epithelium. Therefore, testicular morphologic alterations may possibly be due to hormonal changes.

[Chronic intravenous toxicity studies of potassium clavulanate and BRL28500 in dogs]

The chronic toxicity of potassium clavulanate (CVA-K) and BRL28500 were evaluated using dogs in 26-week intravenous administration studies followed by a 5-week off-dose period. The doses for CVA-K and BRL28500 were 10, 20, 50 and 100 mg/kg (p.f.a.), and 80, 160, 320 and 800 mg/kg (p.f.a.) respectively. There were no deaths in either of the groups. For general condition, dogs dosed with CVA-K at 100 mg/kg showed reddening of the skin and mucous membranes, shaking of the head, facial oedema, a decrease in food intake and a reduction in body weight. Also some dogs of the same group showed decreased spontaneous activity, emaciation and signs of dehydration. In the BRL28500 treatment groups, there was reddening of the skin and mucous membranes, vomiting and salivation at 800 mg/kg. Urinalysis of dogs dosed with CVA-K showed occasional dark yellow coloration of the urine. There was also a very weak and equivocal response or positive reaction for protein, occult blood, and urine sugar in some animals at 100 mg/kg. Some dogs dosed with BRL28500 also showed either a very weak and equivocal response or slight positive reaction for occult blood at 320 mg/kg and above, and dark yellow coloration of the urine at 800 mg/kg. Haematological examination of the CVA-K groups showed increases in leukocyte count and platelet count at the highest dose of 100 mg/kg. No haematological abnormalities were noted in any of the BRL28500 groups. Serum biochemical studies of dogs dosed with CVA-K revealed a decrease in total protein at 50 mg/kg and above, and increases in Al-P, total bilirubin, GPT, BUN and creatinine at 100 mg/kg. In the BRL28500 treatment groups, there were increases in total cholesterol and triglyceride at 160 mg/kg and above. In dogs dosed with CVA-K there was an increase in liver weight at 100 mg/kg. Histopathological examination showed a ground glass-like appearance of the hepatocyte cytoplasm and also altered distribution of PAS positive material at 50 mg/kg and above. In the BRL28500 groups, there was an increase in liver weight at 320 mg/kg and above. There were the same ground glass-like appearance in hepatocytes and altered distribution of PAS positive material at 800 mg/kg. In view of the above results, the maximum non-effect dose levels in the present studies were considered to be 20 mg/kg for CVA-K and 80 mg/kg for BRL28500.(ABSTRACT TRUNCATED AT 400 WORDS)

Biological studies on the degradation products of 3-[(S)-1'-phenylethylamino]propylaminobleomycin: a novel analog (pepleomycin)

Pepleomycin (PEP), 3-[(S)-1'-phenylethylamino]propylaminobleomycin has potent activity and is less pulmonary toxic than bleomycin (BLM). Biological activity and toxicity of the following degradation products of PEP have been studied in detail: the product of carbamoyl migration (ISO), the product of decarbamylation (DC), the product of ring closure of the side chain on the pyrimidine moiety (RC), the depyruvamide product (DP) and the product of an enzymatic inactivation (DA). These degradation products showed much lower activity than PEP in vitro: antimicrobial and anti-HeLa activities, inhibition of DNA synthesis in AH66 cells and the DNA strand cleavage. Acute toxicity and pulmonary toxicity were tested in mice. Results indicated much lower acute toxicity corresponding to the decreased in vitro activity when compared to PEP. DP and RC did not cause lung fibrosis in mice, while ISO and DC showed 1/2.6 and 1/5.7 degree of pulmonary toxicity, respectively, in comparison with PEP.

[Studies on organ distribution, absorption and excretion of pepleomycin sulfate (NK631) (author's transl)]

1. Organ distribution of pepleomycin (NK631) in mice and rats was studied. NK631 was found at higher levels than bleomycin (BLM) in skin, lung, stomach, solid tumor, etc. in mice and rats. Furthermore NK631 was detected in the mesenteric and lumbar lymph node, esophagus and prostate in rats and also distributed at about twice as high levels as BLM in the AH109A hepatoma cell-metastasized lymph nodes. 2. For the elucidation of reason on low pulmonary toxicity of NK631 which is in spite of 1.5 times highly distribution in lung compared with BLM, inactivation of various BLMs by high molecular fraction of lung of mice and rats was determined. The order of inactivation rate of various BLMs in lung was as follows: BLM-M5196 greater than NK631 greater than BLM greater than BLM-HPE. There is an encouraging coincidence between index of pulmonary fibrosis in mice and inactivating rate in lung. 3. A comparative study on the serum level and urinary excretion of NK631 and BLM was performed in dogs. The blood level and urinary excretion rate of both drugs were almost similar. 4. The blood levels of NK631 were comparable to those of BLM in cancer patients.

[Studies on antitumor activities and pulmonary toxicity of pepleomycin sulfate (NK631) (author's transl)]

The antimicrobial and antitumor activities, and the pulmonary toxicity of pepleomycin (NK631) were studied in comparison with bleomycin (BLM). NK631 showed a broad antimicrobial spectrum against gram positive and gram negative bacteria equally to BLM, and its activity was about twice higher than BLM. NK631 showed higher activity on cultured HeLa S3 cells and higher antitumor effect on the transplanted tumors of Ehrlich solid carcinoma in mice, AH66 and AH66F ascites hepatoma in rats, and lower antitumor effect on Ehrlich ascites carcinoma in mice than BLM. Similarly to BLM, NK631 did not show satisfactory activity on L1210 leukemia in mice. NK631 showed marked effect on chemically induced squamous cell carcinoma, spontaneous lymph sarcoma of a dog, human and dog gastric cancer heterotransplanted in nude mice equally to BLM. Furthermore NK631 exhibited remarkably higher antitumor activity on lymph node metastasis of AH66 ascites hepatoma of rats and chemically induced gastric carcinoma of rats than BLM. Pulmonary toxicity of NK631 was low as 1/3 in incidence and 1/4 in grade of the BLM in old mice system. This trend was confirmed by chemical analysis of hydroxyproline in lung.

[Safety evaluation of NK 631. Antigenicity, effect on delated hypersensitivity, irritative effect on eye mucous membrane and mutangenicity of pepleomycin (NK 631) (author's transl)]

1. Whether NK 631 is antigenic to guinea pigs and rabbits was studied by the methods of active and passive anaphylactic shock tests, Schultz-Dale reaction, passive cutaneous anaphylaxis, Ouchterlony, tanned red cell haemagglutination test and test according to the U.S. Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics. However, none of the tests proved NK 631 to be antigenic. 2. The immunosuppressive effect of NK 631 was studied by delayed hypersensitivity to picryl chloride in normal and L-1210 tumor bearing mice. Therapeutic dosis of NK 631 was no immunosuppressed but toxic dosis of NK 631 was slightly decreased in ear thickness of delayed hypersensitivity. 3. The acute irritative effect of NK 631 and of bleomycin was studied by single instillation to the rabbit eye mucous membrane with 0.1 ml of either of 10, 33 and 100 mg/ml solution of the drugs in physiological saline. The irritative effect of NK 631 on the eye mucous membrane at each concentration was slightly severe than that of bleomycin at the same concentration. However, the manifestations were only mild to moderate dilatation of the conjunctival and nictating membrane blood vessels and eye mucous, and recovered or were mitigated 48 hours after the instillation. No severe changes such as corneal opacity, corneal desquamation, swelling and deaquamation of the conjunctival and nictating membrane were observed. The histopathological examination revealed no striking changes. 4. Mutagenicity of NK 631 and of bleomycin on Salmonella typhimurium strain TA 100 and TA 98 was studied. It was definitely shown that neither NK 631 nor bleomycin exerted any mutagenic action on either test strains.

[Toxicological studies of pepleomycin sulfate. V. Short term intermittent toxicity in dogs (author's transl)]

The comparative studies in the short term intermittent toxicity of pepleomycin (NK631) and bleomycin (BLM) were performed on 10 beagle dogs of 13 approximately 15 months old. Two dogs per group were injected intravenously with NK631 and BLM in doses 5.0 and 2.5 mg/kg body weight every fourth day for 11 treatment. Two dogs served as control and were injected with saline solution. In the group of 5.0 mg/kg of NK631, one dog was sacrificed on day 37 of the treatment and another one dog died on day 33 of the treatment. All the dogs of other group survived until the end of the treatment. The toxicity to the hepatic and renal damage caused by NK631 was stronger than the BLM. On the contrary, the toxicity to lung and various mucocutaneous regions was weaker than the BLM. The grade of pulmonary fibrosis of NK631 was about 1/2 and 2/3 of the BLM in dose of 5 mg/kg and 2.5 mg/kg, respectively. Other toxicological changes such as anorexia and weight loss were almost similar to the BLM.