Modulation of Melatonin Receptors Regulates Reproductive Physiology: The Impact of Agomelatine on the Estrus Cycle, Gestation, Offspring, and Uterine Contractions in Rats

Agomelatine is a pharmaceutical compound that functions as an agonist for melatonin receptors, with a particular affinity for the MT1 and MT2 receptor subtypes. Its mode of action is integral to the regulation of diverse physiological processes, encompassing the orchestration of circadian rhythms, sleep-wake cycles, and mood modulation. In the present study, we delve into the intricate interplay between agomelatine and the modulation of estrus cycles, gestation periods, offspring numbers, and uterine contractions, shedding light on their collective impact on reproductive physiology. Both in vivo and in vitro experiments were performed. Wistar Albino rats, divided into four groups: two non-pregnant groups (D1 and D2) and two pregnant groups (G1 and G2). The D1 and G1 groups served as control groups, while the D2 and G2 groups received chronic agomelatine administration (10 mg/kg). Uterine contractions were assessed in vitro using myometrial strips. Luzindole, a melatonin receptor antagonist, was employed to investigate the pathway mediating agomelatine's effects on uterine contractions. In in vivo studies, chronic agomelatine administration extended the diestrus phase (p<0.05) in non-pregnant rats, prolonged the gestational period (p<0.01), and increased the fetal count (p<0.01) in pregnant rats. Additionally, agomelatine reduced plasma oxytocin and prostoglandin-E levels (p<0.01) during pregnancy. In vitro experiments showed that agomelatine dose-dependently inhibited spontaneous and oxytocin-induced myometrial contractions. Luzindole (2 µM) reverse the agomelatine-induced inhibition of myometrial contractions. These findings suggest that agomelatine holds the potential to modulate diverse reproductive parameters during the gestational period, influencing estrus cycling, gestational progression, offspring development, and the orchestration of uterine contractions.

An Evaluation of the Effectiveness of Melatonin and n-Acetylcysteine in Cerebral Ischemia-Reperfusion Injury in Adult Rats

Background and Objectives: The purpose of this study was to apply histopathological and immunohistochemical methods to compare the protective efficacy of melatonin and N-acetylcysteine (NAC) application in rats with experimental brain ischemia/reperfusion (I/R) injury induced through occlusion of the middle cerebral artery (MCA), and to evaluate the protective effect of their combined use. Materials and Methods: Forty-one young adult male Wistar albino rats were divided into five groups-control (n = 8), I/R group (n = 8), melatonin (n = 8), NAC (n = 8), and melatonin + NAC (n = 9). Results: All scores differed between the groups, apart from vascular congestion (p < 0.05). At two-way comparisons, all histological scores were significantly higher in the I/R group than in the control group (p < 0.05). No change occurred in the vascular congestion scores with the administration of melatonin, although decreases were determined in all other scores. These decreases were statistically significant for cellular eosinophilic pyknotic degeneration, vacuolization, and edema (p < 0.05). All histopathological scores in the group administered NAC together with melatonin were significantly lower than in the I/R group (p < 0.05). Conclusions: The combined use of NAC and melatonin, the neuroprotective efficacy of which on histopathological parameters is shown in this study, now needs to be supported by further research.

Treadmill Exercise Improves Behavioral and Neurobiological Alterations in Restraint-Stressed Rats

Stress is a state that is known to impact an organism's physiological and psychological balance as well as the morphology and functionality of certain brain areas. In the present work, chronic restraint stress (CRS) model rats treated with treadmill exercise were used to examine anomalies associated to emotion and mood as well as molecular changes in the brain. Forty male Sprague-Dawley rats were divided into control, stress, exercise, and stress+exercise groups. CRS were exposed to stress group rats and exercise group underwent a chronic treadmill exercise. Depressive-like behavior was evaluated with the forced swim test (FST) and tail suspension test (TST). For assessing anxiety-like behavior, the light-dark test (LDT) and the open field test (OFT) were used. The Morris water maze test (MWMT) was used for testing memory and learning. Brain's monoamine level and the expression of genes related to stress were measured. It was discovered that CRS lengthens latency in the MWMT, increases immobility in the FST and TST, decreases time in the light compartment, and causes hypoactivity in the OFT. CRS reduced the dopamine levels in the nucleus accumbens(NAc). Brain-derived neurotrophic factor (BDNF), dopamine receptors, and serotonin receptor (HTR2A) gene expression in the prefrontal cortex, corpus striatum, and hypothalamus were decreased by CRS. Exercise on a treadmill leads to increase NAc's dopamine and noradrenaline levels and prevented behavioral alterations. Exercise increased the alterations of BDNF expressions in the brain in addition to improving behavior. As a result, CRS-induced behavioral impairments were effectively reversed by chronic treadmill exercise with molecular alterations in the brain.

TRPM2 may be involved in high fructose corn syrup-induced anxiety-like behavior in adult male rats

Excessive high fructose corn syrup (HFCS) consumption is known to cause oxidative stress, which induces transient receptor potential melastatin type 2 (TRPM2) channel gating. Oxidative stress-induced TRPM2 gating is suggested to play an important role in neurons, indicating a role for the TRPM2 channel in a variety of neuropsychiatric disorders including depression and anxiety. We investigated the effects of HFCS and chronic immobilization stress (CIS) on TRPM2 channel immunoreactivity, anxiety, and depressive-like behaviors in adult male rats. The male rats (n=8/group) were divided into 4 groups: Control, 20% HFCS (F20), 40% HFCS (F40), and stress. The control group received tap water, and F20 and F40 groups were exposed to HFCS 20% and 40% respectively for 14 consecutive days. Rats in the stress group were subjected to immobilization stress for 3 or 6 hours daily in the first and second weeks to induce CIS. Then, light/dark tests, open field tests (OFT), and tail suspension tests (TST) were performed, respectively. In the light/dark test, the time spent in the dark chamber significantly increased in all groups vs the control group (P<0.01). In support of this result, time spent in the light chamber significantly decreased in all groups vs the control group (P<0.01). Besides, CIS significantly increased depressive-like behavior in the stress group vs the control group (P<0.05). In serum hormone levels, corticosterone (CORT) levels significantly increased in the F40 and stress groups vs the control group (P<0.01). TRPM2 immunoreactivity significantly increased in the hippocampus, prefrontal cortex (PFC), nucleus accumbens (NaC), and amygdala regions by HFCS and CIS treatments. For the first time in the present study,  showed that f increased immunoreactivity of the TRPM2 cation channels may be linked to the anxiety-like behavior induced by HFCS.

Treadmill exercise has healing effects on obesity-induced sexual behavior disorder through kisspeptin and kiss1R expression in male rats

The basic objective of this study was to examine the possible effects of treadmill exercise on obesity-related sexual behavior disorder in obese male rats and the role of kisspeptin in this effect. The rats were separated from their mothers at the age of 3 weeks, and classified into four groups as Control (C): normal diet-sedentary group, Exercise (E): normal diet-exercise group, Obese (O): high-fat diet-sedentary group, Obese + Exercise (O+E): high-fat diet-exercise grouSexual behavioral testing was conducted in the rats. At the end of the study, brain samples were taken from the animals for gene expression analyses. The treadmill exercise caused a significant increase in the O+E Group compared to the O Group in kisspeptin and kiss1R gene expression and in EF, ML, IL, MF, IF, III, EL, PEI, IR1, MFT, IFT, IRT sexual behavior parameters (p<0.05), and a significant decrease in ML, IL, III, EL sexual behavior parameters (p<0.05). Treadmill exercise caused a significant decrease in EF, ML, IL, MF, IF, III, EL, PEI, IR1, MFT, IFT, IRT sexual behavior parameters and kisspeptin and kiss1R gene expression in the hypothalamus, hippocampus, prefrontal cortex and corpus striatum in E Group compared to C Group (p<0.05), and a significant increase in ML, IL, III, EL sexual behavior parameters (p<0.05). Based on this effect, we believe that it is caused by an increase in kisspeptin and kiss1R expression in the hypothalamus, hippocampus, prefrontal cortex and corpus striatum. In conclusion, treadmill exercise-induced kisspeptin secretion may increase GnRH secretion and cause hypothalamo-pituitary gonadal axis activation and ameliorative effect on deteriorated sexual function.

Expression of phoenixin-14 and nesfatin-1 in the hypothalamo-pituitary-gonadal axis in the phases of the estrous cycle

Phoenixin-14 (PNX-14) and nucleobindin 2 (NUCB2)/nesfatin-1 are regulatory neuropeptides expressed in the hypothalamus. These neuropeptides can be effective in hormonal regulation of the hypothalamo-pituitary-gonadal (HPG) axis and reproductive functions. In the present study, the distribution of PNX-14 and NUCB2/nesfatin-1 in the hypothalamus, pituitary, ovary, and uterus tissues during the phases of the estrous cycle in female rats was investigated. Eighteen Wistar Albino rats determined among animals showing regular estrous cycle by vaginal smear method were divided into three groups: proestrus (Group I), estrus (Group II) and diestrus (Group III). Serum gonadotropin-releasing hormone (GnRH), plasma PNX-14, and NUCB2/nesfatin-1 concentrations were the highest, moderate, and lowest in estrus, diestrus, and proestrus phases, respectively. PNX-14 immunoreactivity in the supraoptic and arcuate nuclei of the hypothalamus and NUCB2/nesfatin-1 immunoreactivity in the paraventricular nuclei were particularly evident in the estrus phase. These neuropeptide immunoreactivities were decreased in different cells of anterior pituitary during proestrus compared with those during estrus and diestrus. PNX-14 immunoreactivity in the ovary, especially during the estrus phase, was diffuse and intense in the granulosa and luteal cells and oocytes, and it was few and weak in theca cells. In addition, NUCB2/nesfatin-1 immunoreactivity was abundant and strong in granulosa and luteal cells, theca and interstitial cells, and oocytes during estrus. In the estrus phase, PNX-14 immunoreactivity was strong in the glandular epithelial cells and stromal cells of the endometrium, also NUCB2/nesfatin-1 immunoreactivity was strong in the epithelial and glandular epithelial cells. As a result, when the estrous cycle was evaluated, it was concluded that the changes in the distribution of PNX-14 and NUCB2/nesfatin-1 at all phases were related to GnRH and that these neuropeptides showed the highest immunoreactivity especially in the HPG axis and uterus tissues of estrus rats.

The modulatory effects of irisin on asprosin, leptin, glucose levels and lipid profile in healthy and obese male and female rats

OBJECTIVES

The main aim of this study was to investigate the effects of irisin on asprosin, leptin, glucose levels and lipid profile in healthy and obese male and female rats.

METHODS

Irisin was subcutaneously administered with osmotic minipumps at the dose of 100 ng/kg/day for 28 days and then, the serum levels of asprosin, leptin, glucose and lipid profile were investigated.

RESULTS

Irisin infusion increased asprosin levels in male rats (p = .02) but not in female rats. Irisin inhibited obesity-induced high glucose, low-density lipoprotein (LDL), triglyceride (TG) and leptin levels in all groups; however, it did not lead to any change in asprosin levels in both obese female and male rats.

CONCLUSIONS

It was determined that irisin increased serum asprosin levels and decreased LDL, TG, glucose and leptin levels, and this could indicate a protective role of irisin against obesity development.

Asprosin, a novel therapeutic candidate for painful neuropathy: an experimental study in mice

Recent studies indicate presence of a strong link between adipokines and neuropathic pain. However, the effects of asprosin, a novel adipokine, on neuropathic pain have not been studied in animal models.Mouse models were employed to investigate the antinociceptive effectiveness of asprosin in the treatment of three types of neuropathic pain, with metabolic (streptozocin/STZ), toxic (oxaliplatin/OXA), and traumatic (sciatic nerve ligation/CCI [chronic constriction nerve injury]) etiologies, respectively. Changes in nociceptive behaviors were assessed relative to controls using thermal (the hot plate and cold plate tests, at 50 °C and 4 °C respectively) and mechanical pain (von Frey test) tests after intraperitoneal (i.p.) administration of asprosin (10 µg/kg) and gabapentin (50 mg/kg) in several times intervals. Besides, possible effect of asprosin on the motor coordination of mice was assessed with a rotarod test. Serum level of asprosin was quantified by ELISA.In neuropathic pain models (STZ, OXA, and CCI), asprosin administration significantly reduced both mechanical and thermal hypersensitivity, indicating that it exhibits a clear-cut antihypersensitivity effect in the analyzed neuropathic pain models. The most effective time of asprosin on pain threshold was observed 60 min after its injection. Also, asprosin displayed no notable effect on the motor activity. Asprosin levels were significantly lower in neuropathic pain compared to healthy group (p < 0.05).The results yielded by the present study suggest that asprosin exhibits an analgesic effect in the neuropathic pain models and may have clinical utility in alleviating chronic pain associated with disease and injury originating from peripheral structures.

Irisin Improves High-Fat Diet-Induced Sexual Dysfunction in Obese Male Rats

INTRODUCTION

Obesity is known to cause sexual dysfunction including erectile dysfunction and poor semen quality. Lifestyle modifications such as exercise have increasingly been more recognized to lower the likelihood of having sexual dysfunction or infertility in obese men. In this context, as an exercise-mimetic hormone, irisin has a potential to improve obesity-related reproductive dysfunctions. We aimed to elucidate possible effects of irisin on high-fat diet (HFD)-induced reproductive dysfunction in obese male rats.

METHODS

Rats were divided into four groups: vehicle, irisin, obese, and obese + irisin. The rats in obese and obese+irisin groups were fed with HFD (60% kcal fat) pellets for 12 weeks to induce obesity, and then obesity-induced sexual dysfunction was confirmed by the sexual behavior test (SBT). Irisin and obese+irisin groups received irisin (100 ng/kg/day) infusion by an s.c. osmotic minipump for 4 weeks after HFD-induced obesity was formed.

RESULTS

Irisin did improve a number of measures of copulation, including penile erection, ejaculation, and sexual performance, and also improved sperm morphology and motility and decreased fat-induced testicular damage. It decreased serum leptin levels. On the other hand, irisin did not affect serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone. It also increased gene expression of tyrosine hydroxylase (TH) and adrenoceptor alpha 1A (ADRA1A) in the medial preoptic area (mPOA) and nucleus accumbens (NAc).

CONCLUSION

Irisin provided a marked enhancement of HFD-induced decrease in libido, potency, sexual performance, and erection in SBT. Taken together, our results emphasize that irisin has a restorative and improver role in HFD-induced reproductive dysfunctions in obese male rats.

Effects of treadmill exercise on sexual behavior and reproductive parameters in chronically stressed-male rats

Exposure to chronic stress stimulates the hypothalamic-pituitary-adrenal (HPA) axis and then simultaneously inhibits hypothalamic-pituitary-gonadal axis (HPG) axis activity. The inhibition formed by the HPA axis is the main mechanism of action of stress on reproductive function. HPG axis activity is known to be changed by various factors, including exercise. Exercise has been found to have a number of positive effects on sexual behavior, reproductive hormones, and sperm parameters in studies with animal models for many years. The main aim of this study is to investigate the effects of chronic treadmill exercise on chronically stressed-male rats' sexual behavior, reproductive hormones, and sperm parameters. A total of 40 sexually adult male rats were randomly and equally divided into four groups as control, stress, exercise, and stress+exercise. Animals in the exercise group were subjected to the chronic treadmill exercise (moderate intensity) for 33 days with a periodic increase in speed and duration. Animals in the stress group were exposed to restraint stress for 1 h, 2 h, and 3 h during the first, second and third 15 days respectively. Sexual behavior parameters, hormone measurements, and sperm parameters were evaluated. The main effects of chronic exercise on sexual behavior were centered on a significant increase in the ejaculation frequency (EF) in the stress+exercise group. Also, sperm concentration and motility in the stress group significantly decreased, and then sperm motility was improved by exercise in the stress+exercise group. In sum, our results show that chronic treadmill exercise may improve the adverse effects of chronic stress on sexual behavior and sperm parameters in male rats in terms of some parameters.

Irisin may have a role in pubertal development and regulation of reproductive function in rats

Physical exercise and body muscle/fat mass are known to affect the endocrine system, puberty onset and reproductive health. However, the potential effects of irisin, an adipo-myokine and exercise-induced hormone, have not yet been fully elucidated on reproductive maturation. Therefore, the present study aimed to determine the effects of irisin administration on pubertal maturation and reproductive system in female and male rats. Daily i.p. injection of irisin (100 ng/kg; from postnatal day 21 for about 10 weeks) delayed the ages at the vaginal opening (as an external index of puberty onset) and first estrus. Furthermore, continuous administration of irisin to female rats caused a significant decrease in serum follicle-stimulating hormone levels and an increase in serum luteinizing hormone and 17β-estradiol levels, as well as causing histopathological changes in the ovarian tissue. On the contrary, irisin administration to male rats did not modify the timing of puberty, as estimated by age at preputial separation. However, chronic exposure to irisin produced significant increases in serum luteinizing hormone and testosterone levels and also sperm concentration and seminiferous tubule diameter in male rats. In conclusion, irisin exposure has different effects on both pubertal maturation and reproductive system in female and male rats. The present findings reveal that chronic irisin exposure may lead to disorders in the female reproductive system and may have androgenic potential on the hypothalamic-pituitary-gonadal axis in males.

Gonadotropin levels reduced in seven days immobilization stress-induced depressive-like behavior in female rats

OBJECTIVES

Reproduction is one of the physiological functions that are often negatively affected by chronic stress. We aimed to examine effects of two distinct 7-day chronic immobilization stress (IMO) models on gonadotropins levels and depression-like behaviors in female rats.

METHODS

Adult Wistar albino female rats were divided into three groups as follows (n=7 for each group): control, IMO-1 (45 min daily for 7-day) and IMO-2 (45 min twice a day for 7-day). Neuropsychiatric behaviors were determined by using forced swimming test (FST) and open field test (OFT). Gonadotropins were analyzed using ELISA tests.

RESULTS

In FST, swimming was lower, and immobility was higher in the IMO-1 group and IMO--2 group. Climbing score of the IMO-2 group was higher compared to the control group. In OFT, there was no significant alteration in the mean velocity, total distance, duration of time spent in the central area and duration of latency in the central area between the stress groups and the control group. Final body weight and percentage of body weight change were lower in both stress groups. The follicle-stimulating hormone level was lower only in the IMO-2 group, and the luteinizing hormone concentrations were significantly lower in the IMO-1 group and IMO-2 group.

CONCLUSIONS

Our results indicated that depression-like behaviors increased, and gonadotropins decreased in the female rats exposed to 7-day chronic IMO.

The effect of bee pollen on reproductive and biochemical parameters in methotrexate-induced testicular damage in adult rats

OBJECTIVES

Methotrexate (MTX) is an anticancer drug used in chemotherapy. MTX was known for its toxic effects involving most of the organs including testis. Bee pollen is healthy food for human and has antioxidant effect. We intended to determine protective effect of bee pollen against testicular injury caused by MTX in rats.

METHODS

Thirty-two adult Sprague Dawley male rats were used, and 4 groups were formed: control, MTX, pollen, and MTX + pollen. Rats were given pollen at a dose of 400 mg/kg with intragastric gavage for 10 days. On day 7, MTX was administered a single dose of 30 mg/kg ip. Serum testosterone and LH, tissue MDA level, and SOD and CAT enzyme activities were examined. In addition, spermatological parameters were evaluated.

RESULTS

MDA level and SOD activity increased while testosterone level decreased significantly in the MTX group compared to the control group. In the MTX + pollen group, MDA level and SOD activity decreased while testosterone level increased. There was no significant change in CAT activity and LH values. Abnormal sperm ratio decreased in the MTX + pollen group compared to the MTX group.

CONCLUSIONS

Our results suggest that bee pollen has a healing effect on reproductive parameters in testicular damage caused by MTX.

Agomelatine potentiates anti-nociceptive effects of morphine in a mice model for diabetic neuropathy: involvement of NMDA receptor subtype NR1 within the raphe nucleus and periaqueductal grey

OBJECTIVES

Opioid analgesics have been used for a long time in the treatment of acute and chronic pain. However, they have many side effects including tolerance development to a significant extent. Agomelatine, an atypical antidepressant, has been demonstrated to be effective in experimental studies on pain. However, the effect of agomelatine on morphine tolerance development and its mechanism of action are unknown. The antinociceptive effects of agomelatine, morphine and their combination were assessed in a mice model for painful diabetic neuropathy. The roles of glutamate ionotropic receptor N-methyl-D-aspartate (NMDA) type subunit-1 (GluN1) in raphe nucleus and periaqueductal gray (PAG) in the effect of agomelatine on neuropathic pain were also investigated in diabetic mice.

METHODS

Agomelatine (10 mg/kg), morphine (10 mg/kg) and agomelatine + morphine were administered intraperitoneally for 15 consecutive days (twice per day), and the analgesic responses were assessed at days 1, 3, 6, 9, 12 and 15 in healthy and diabetic mice. Real time polymerase chain reaction (RT-PCR) was used to determine the changes in GluN1 expression.

RESULTS

The tolerance development for morphine was evident, started at 6th day and remained thereafter, but not for agomelatine. GluN1 in raphe nucleus and PAG was upregulated in morphine treated but not in agomelatine-treated groups.

DISCUSSION

The combination of agomelatine with morphine alone causes outlasting analgesic effects of repeated treatment, which can be interpreted as attenuated tolerance. Moreover, we also pointed out for the first time the modulatory effects of agomelatine on GluN1 expression in raphe nucleus and PAG after chronic morphine treatment.

ABBREVIATIONS

Ca²⁺: Calcium; D2DR: Dopamine D2 receptor; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; GluN1: Glutamate ionotropic receptor N-methyl-D-aspartate type subunit-1; 5-HT: 5-hydroxytryptamine; i.p.: intraperitoneal injection; MPE: Maximal possible effect; MT: Melatonin; NMDA: N-methyl-D-aspartate; NMDAR1: NMDA receptors-1; PAG: Periaqueductal grey; PKCγ: Protein kinase C gamma; RT-PCR: Real time polymerase chain reaction; STZ: Streptozotocin.

Kisspeptin and RF9 prevent paroxetine-induced changes in some parameters of seminal vesicle fluid in the male rats

The aim of the study was to examine possible impacts of paroxetine and agomelatine on the levels of some components that constitute the seminal vesicle fluid. As a second purpose, it was also aimed to examine how possible negative effects induced by paroxetine on seminal vesicle fluid components were affected by kisspeptin and RF9 (an RFamide-related peptide antagonist, RFRP). Forty-two male rats, aged 21 days, divided into six groups; control, sham, paroxetine, agomelatine, paroxetine + kisspeptin and paroxetine + RF9. Paroxetine (3.6 mg/kg) and agomelatine (10 mg/kg) were administrated by oral gavage. Kisspeptin (1 nmol) and RF9 (20 nmol) were administered intracerebroventricular (i.c.v). The experiments were ended on post-natal 120 days; fructose, vitamin E, sodium, potassium and magnesium levels were measured in seminal vesicle fluid. Fructose, vitamin E, magnesium and potassium levels were significantly decreased in seminal vesicle fluid from the rats treated with paroxetine but did not show significant differences following agomelatine administration. The co-administration of kisspeptin or RF9 with paroxetine prevented the paroxetine-induced negative effects on seminal vesicle fluid components. These results suggest that reduction in sperm fertilising ability caused by changes in seminal vesicle fluid can be seen in long-term antidepressant use. RF-9 and kisspeptin might have positive effects on long-term antidepressant use-induced infertility.

Effects of restraint stress and high-fat diet on osseointegration of titanium implants: an experimental study

This study aimed to investigate the effects of chronic restraint stress (RS) and a high-fat diet (HFD) on the osseointegration of titanium implants in a rat model. After the surgical insertion of titanium implants into the metaphysis of the tibial bone, the rats were randomly divided into four equal groups (n = 8 each): control (CNT), restraint stress (RS), high-fat diet (HFD), and restraint stress plus high fat diet (RS-HFD). CNT: Rats received no further treatment during the 92-day experimental period. RS: Stress was applied to the rats beginning from two days after the implant surgery for one hour per day for the first 30 days, two hours per day for the next 30 days, and three hours per day for the last 30 days. HFD: Rats were fed a HFD for the following 90 days starting two days after surgery. RS-HFD: Rats were fed a HFD and RS was applied to rats for the following 90 days, starting two days after surgery. At the end of the experimental period, the rats were euthanized, and the implants and surrounding bone tissues were removed for histological analysis. Statistical analysis was performed by one way ANOVA and Bonferrroni tests. There were no significant differences in the bone-implant connection levels between the groups (p > 0.05), but in the HFD and RS-HFD groups, the bone filling ratios were found to be lower compared with the controls (p < 0.05) The data analyzed in this study suggest that an HFD with or without chronic RS adversely affected bone tissue in the rats during the 90-day osseointegration period.

An experimental investigation of the effects of chronic stress on bone-to-implant contact

Objectives

This study aimed to investigate the effects of chronic restraint stress on the osseointegration of titanium implants.

Materials and Methods

Twenty adult male Wistar albino rats were used in the study. After surgical insertion of titanium implants into the metaphyseal part of the tibial bone, rats were randomly divided into two groups: a control group (CNT group) and an experimental restraint stress group (RS group). In the CNT group, titanium implants were inserted surgically, and rats received no further treatment during the 47-day experimental period. In the RS group, restraint stress was applied for 3 hours per day for 45 days, beginning 2 days after implant surgery. Weight of the rats was measured prior to surgery and at the end of the study to analyze the effects of stress. At the end of the experimental period, rats were euthanized, and implants and surrounding bone tissues were used for undecalcified histological analysis. Serum cortisol levels were assessed in cardiac blood samples from the rats following centrifugation.

Results

Average weight of rats in the RS group was lower than that of rats in the CNT group after the experimental protocol had been completed (P<0.05). Further, serum cortisol levels were higher in the RS group than in the CNT group (P<0.05). There were no significant differences in bone-implant connection levels between the two groups (P>0.05).

Conclusion

The data analyzed in this study suggest that chronic restraint stress did not adversely affect rats during a 45-day osseointegration period.

Pinealectomy alters IFN-γ and IL-10 levels in primary thymocyte culture of rats

Melatonin, produced mainly by the pineal gland, has an immunomodulatory role. However, the effects of the pineal gland and/or melatonin on thymus cytokine levels such as interferon-gamma (IFN-γ), interleukin (IL)-4, and IL-10 are not well known. Twenty-one male Wistar rats (220-250 gr) were randomly divided into three groups (n=7): intact control, sham, and pinealectomy. Primary thymocyte cultures were prepared from each group and dispensed into well plates as Control, DMSO (or vehicle), Sham-pinealectomy, Pinealectomy, Pinealectomy+10µM melatonin, and Pinealectomy+100µM melatonin. IFN-γ, IL-4, and IL-10 concentrations were measured in the thymocytes (as nonstimulated and Concanavalin A-stimulated) after 24 h. IFN-γ levels significantly increased and IL-10 levels significantly decreased in both media prepared from pinealectomized rats. There was no significant difference between the groups in terms of IL-4. In the pinealectomy+10µM melatonin group, IFN-γ and IL-10 levels did not differ from the pinealectomy group. However, the dose of 100µM melatonin caused a decrease in levels of IFN-γ in both thymocyte media and an increase in the concentration of IL-10 in Concanavalin A-stimulated thymocytes. In conclusion, pineal gland and/or melatonin affect IFN-γ and IL-10 levels in the thymus gland.

Agomelatine pretreatment prevents development of hyperglycemia and hypoinsulinemia in streptozotocin-induced diabetes in mice

The main objective of this study was to investigate potential effectiveness of agomelatine pretreatment in the prevention of diabetes itself and encephalopathy, with a focus on brain tissue oxidative stress and inflammatory processes in streptozotocin (STZ)-induced diabetic mice. Interleukine-1β (IL-1β) and TACR1 (NK1), which is a tachykinine receptor, were used for the investigation of inflammation in the brain regions including raphe nucleus, periaqueductal gyrus (PAG), amygdala, and nucleus accumbens. The effects of agomelatine on total antioxidant capacity were also evaluated. In the in vitro part of the study, the effects of agomelatine on cell viability were investigated in dorsal root ganglion (DRG) neurons. Fasting blood glucose levels were measured 72 h after STZ injection to determine the diabetic condition. Agomelatine pretreatment prevented both hyperglycemia and hypoinsulinemia in STZ-treated mice. When STZ was injected to induce diabetes in mice, neither hyperglycemia nor hypoinsulinemia was developed in agomelatine pretreated mice and 6 weeks after development of diabetes, agomelatine treatment significantly decreased levels of IL-1β mRNA in raphe nucleus and nucleus accumbens. TACR1 mRNA levels were lower in raphe nucleus, PAG, and amygdala of agomelatine-treated diabetic mice. The increase in total antioxidant capacity after agomelatine administration may responsible for its beneficial effect in the prevention of diabetes. We showed that agomelatine reversed high glucose-induced cell viability decreases in DRG neurons. Both the antihyperglycemic and antioxidant effects of agomelatine might have contributed to the DRG neuron viability improvement. In conclusion, agomelatine seems to both prevent development of diabetes and reverse the encephalopathic changes caused by diabetes.

Magnesium: does it reduce ischemia/reperfusion injury in an adnexal torsion rat model?

Aim

The aim of the present study was to assess the protective effects of magnesium sulfate (MgSO₄) on ischemia/reperfusion (I/R) induced ovarian damage in a rat ovarian torsion model.

Methods

Forty-two female Sprague Dawley rats were included in the study. They were divided into six groups as Group 1, sham; Group 2, bilateral ovarian torsion; Group 3, bilateral ovarian torsion–detorsion; Group 4, MgSO₄–sham; Group 5, MgSO₄–bilateral ovarian torsion; Group 6, bilateral ovarian torsion–MgSO₄–detorsion. Both torsion and detorsion periods lasted 3 hours. In Groups 4, 5 and 6, MgSO₄ (600 mg/kg) was administered by intraperitoneal route 30 minutes before sham operation, torsion and detorsion, respectively. At the end of the study period, both ovaries were removed. One of the ovaries was used for histopathological analyses and the other for biochemical analyses.

Results

In the torsion–detorsion group, all the histopathological scores were higher compared to the sham and torsion only group (p<0.05). Administration of MgSO₄ only caused significant decrease in the inflammatory cell scores of the torsion–detorsion group (p<0.05). MgSO₄, whether given before torsion or before detorsion, suppressed malondialdehyde levels when compared to the untreated groups (p<0.01 and p<0.001, respectively). Glutathione peroxidase activities were significantly higher in the MgSO₄ applied torsion and detorsion groups than Groups 2 and 3 (p<0.05, for both). Administration of MgSO₄ also caused an increase in glutathione levels in the torsion and detorsion groups compared to the torsion only and detorsion only groups (p<0.05, for both). Also, total oxidant status levels decreased in the MgSO₄ applied torsion and detorsion groups compared to the untreated corresponding ones (p<0.01 and p<0.001, respectively). MgSO₄ significantly decreased the Oxidative Stress Index levels in the torsion–detorsion group compared to Group 2 (p<0.001).

Conclusion

Histopathological and biochemical analysis revealed that prophylactic treatment with MgSO₄ reduces the changes observed in I/R injury in a rat model.

Studies on the reproductive effects of chronic treatment with agomelatine in the rat

Agomelatine is an antidepressant with a novel mechanism of action. It is a melatonergic agonist for MT1 and MT2 receptors and a serotonin (5-HT2C) receptor antagonist. Agomelatine has been suggested not to have adverse effects on sexual functions. However, the effects of chronic agomelatine administration on reproductive functions have not been sufficiently studied in animal models. We mainly aimed to explore the effects of agomelatine on reproductive functions in the male and female rats. For the experimental studies, Sprague Dawley rats were used. The animals started to receive daily oral agomelatine (10mg/kg) on post-natal day 21. Agomelatine advanced vaginal opening in the female rats whereas it delayed puberty onset in the male rats. Agomelatine treatment significantly decreased intromission frequencies, which indicates a facilitator role of this antidepressant on male sexual behavior. In the forced swimming test (FST) used for assessing antidepressant efficacy, agomelatine induced a significant decrease in duration of immobility, and an increase in the swimming time, respectively, which confirms the antidepressant-like activity of agomelatine. The present findings suggest that agomelatine shows a strong antidepressant effect in the male rats without any adverse influences on sexual behavior, and its effects on pubertal maturation seem to show sex-dependent differences.

The effects of lipopolysaccharide-induced endogenous hyperthermia and different antipyretic treatment modalities on rat brain

BACKGROUND

In the present study, the effects of fever and hyperthermia, and different anti hyperthermia treatment modalities on the brain by was investigated by using experimental animal model

MATERIALS AND METHODS

Endogenous hyperthermia (41 degrees C) was induced by lipopolysaccharide (LPS) injection, and the signs of probable neuronal damage were evaluated by healthy, necrotic and apoptotic cells, and heat-shock proteins (HSP 27 and HSP 70) in cerebral cortex, cerebellum and hypothalamus. The animals were treated with widely used treatment modalities for high fever in pediatric practice, namely hypothermia, dexamethasone, paracetamol and diclofenac, and their effect on the hyperthermia-induced brain changes were evaluated.

RESULTS

Generalized seizure was observed in fifteen rats of which rectal temperature achieved 41 degrees C (15/36, 41%); five of them died on second day (5/15, 33%). LPS-induced endogenous hyperthermia; (i) caused significant increase of necrotic cells in cerebral cortex and cerebellum and apoptotic cells in all three regions (p < 0.05), (ii) caused significant decrease of healthy cells in cerebral cortex (p < 0.05), and (iii) no significant change of HSP 27 and 70 in all three neuronal locations (p > 0.05). For the treatment modalities applied; (i) paracetamol had an effect of increasing the healthy cell count in cerebral cortex and hypothalamus and decreasing the necrotic cell count in cerebellum and hypothalamus (p < 0.05).

CONCLUSION

The neuronal tissue in different regions of brain can show various degrees of damage in response to endogenous hyperthermia and the applied medications have varying degree of protection (Tab. 3, Fig. 6, Ref. 44).

Preventive role of genistein in an experimental non-alcoholic steatohepatitis model

BACKGROUND AND AIM

The aim of the present study was to evaluate the preventive role of genistein, a phytoestrogen with a wide variety of pharmacological effects, in an experimental non-alcoholic steatohepatitis (NASH) model.

METHODS

Thirty-six Sprague-Dawley rats were divided into three groups. Group 1 (control) received only a standard rat diet, group 2 (placebo) was given a high fat diet (HFD) plus 0.5 mL/day saline subcutaneously, and group 3 (genistein group) a HFD plus subcutaneous genistein injection at dose of 0.2 mg/kg/day for 6 weeks. All rats were killed after 6 weeks. Serum aminotransferases, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and plasma and liver malondialdehyde (MDA) levels were measured. Additionally, steatosis, ballooning degeneration and inflammation of the liver were examined histopathologically.

RESULTS

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (P < 0.001 for each), plasma and liver tissue MDA and plasma TNF-alpha levels (P < 0.001, <0.001, <0.01, respectively) were found to be higher in the placebo group than in the control group. TGF-beta levels, however, were comparable in the placebo and control groups (P > 0.05). Histopathologically, steatosis, inflammatory cells per mm(2) and ballooning degeneration were significantly higher in the placebo group than in the control group (P < 0.001 for each). Nevertheless, AST and ALT (P < 0.05 for each), plasma and liver tissue MDA (P < 0.05 for each) and plasma TNF-alpha levels (P < 0.001) were significantly decreased in the genistein group compared to the placebo group. Histopathologically, steatosis (P < 0.05), inflammatory cells per mm(2) and ballooning degeneration (P < 0.01 for each) in the genistein group were also significantly lower than in the placebo group.

CONCLUSIONS

Genistein, a strong antioxidant agent, significantly decreased the plasma TNF-alpha level and remarkably prevented the emergence of NASH by improving the biochemical and histopathological abnormalities via attenuating oxidative stress.

Preventive role of genistein in an experimental non-alcoholic steatohepatitis model

BACKGROUND AND AIM

The aim of the present study was to evaluate the preventive role of genistein, a phytoestrogen with a wide variety of pharmacological effects, in an experimental non-alcoholic steatohepatitis (NASH) model.

METHODS

Thirty-six Sprague-Dawley rats were divided into three groups. Group 1 (control) received only a standard rat diet, group 2 (placebo) was given a high fat diet (HFD) plus 0.5 mL/day saline subcutaneously, and group 3 (genistein group) a HFD plus subcutaneous genistein injection at dose of 0.2 mg/kg/day for 6 weeks. All rats were killed after 6 weeks. Serum aminotransferases, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and plasma and liver malondialdehyde (MDA) levels were measured. Additionally, steatosis, ballooning degeneration and inflammation of the liver were examined histopathologically.

RESULTS

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (P < 0.001 for each), plasma and liver tissue MDA and plasma TNF-alpha levels (P < 0.001, <0.001, <0.01, respectively) were found to be higher in the placebo group than in the control group. TGF-beta levels, however, were comparable in the placebo and control groups (P > 0.05). Histopathologically, steatosis, inflammatory cells per mm(2) and ballooning degeneration were significantly higher in the placebo group than in the control group (P < 0.001 for each). Nevertheless, AST and ALT (P < 0.05 for each), plasma and liver tissue MDA (P < 0.05 for each) and plasma TNF-alpha levels (P < 0.001) were significantly decreased in the genistein group compared to the placebo group. Histopathologically, steatosis (P < 0.05), inflammatory cells per mm(2) and ballooning degeneration (P < 0.01 for each) in the genistein group were also significantly lower than in the placebo group.

CONCLUSIONS

Genistein, a strong antioxidant agent, significantly decreased the plasma TNF-alpha level and remarkably prevented the emergence of NASH by improving the biochemical and histopathological abnormalities via attenuating oxidative stress.