Aberrant effect of genistein on placenta development expressed through alteration in transforming growth factor-ß1 and alkaline phosphatase across the maternal serum, the placenta and the amniotic fluid.

OBJECTIVES: The mechanism via which genistein, the major isoflavone content of soya, adversely influenced placenta and fetal development was evaluated in pregnant laboratory rats. MATERIALS AND METHODS: There were control, 2 mg/kg and 4 mg/kg genistein groups of rats with five sub-groups based on gestation termination day. At the end of the experiment, animals were sacrificed by CO2 and cervical dislocation, while plasma and serum were processed and stored. The abdomen was opened and the amniotic fluid was siphoned from the uterine sacs, processed and stored. The embryonic implants were excised, the placenta was separated from the fetus and weighed separately. Placenta homogenate was prepared from the harvested placenta, while the rest were processed for histological studies. Transforming growth factor (TGf-ß1) and alkaline phosphatase (ALP) were assayed for in all samples. A significant decrease in the placenta and fetal weights, and a significant decrease in serum and placenta homogenate ALP levels were recorded in genistein groups. RESULTS: There was a reduction in the Trophoblast giant cells population (TGCs). TGCs zone depth, perimeter, and an increase in the placenta and amniotic fluid's TGf-ß1 in all genistein groups at GD-13 towards term, and GD-18 and GD-20, respectively. Maternal plasma TGf-ß1 was increased in 2 mg group early in pregnancy while its level significantly decreased in both 2 mg and 4 mg genistein groups at mid-gestation towards GD-19. CONCLUSION: Genistein aberrant effect on fetal development was via its adverse effect on TGCs proliferation and TGf-ß1 activities in the placenta tissue.

High-Dose Perinatal Folic-Acid Supplementation Alters Insulin Sensitivity in Sprague-Dawley Rats and Diminishes the Expression of Adiponectin.

The possible intake of folate in excess of the recommended upper levels is a matter of critical importance. This study was conducted to investigate the effects of prenatal and postnatal high folic acid supplementation (FAS) on glucose tolerance, insulin sensitivity, lipid metabolism, and expression of adiponectin in rats. The study included 20 female rats divided into two groups: control group and FAS group (receiving high folic acid supplemented diet). Both groups of female rats were mated and pregnancy confirmed. At parturition, the diet of 5 dams that were fed with control diet during gestation and their litters was changed to FAS diet and continued throughout lactation. Similarly, half of the dams that were previously fed with FAS diet during gestation and their litters were also changed to control diet. The remaining 5 dams in each group continued on their respective diets throughout lactation with their litters. Other dams remained on their respective diets throughout lactation. Food and water intake, body weight, lipid concentrations, insulin, and the expression of adiponectin were determined. Glucose tolerance and insulin sensitivity were also measured to evaluate glucose homeostasis. FAS significantly increased the postweaning food, water intake, triglyceride, and insulin levels but diminished insulin sensitivity in adult offspring. The expression of adiponectin in insulin-sensitive tissues was also significantly decreased and these were consistent with insulin resistance of FAS offspring. High-dose FAS may promote insulin resistance and dyslipidemia and disrupt glucose metabolism possibly by depressing adiponectin expression. Although this is an animal model and the effects of the diets cannot be directly transposed to humans, this study provides indications of the possible adverse effects of FAS maternal diet on glucose metabolism in the offspring.

Adverse effects of noise stress on glucose homeostasis and insulin resistance in Sprague-Dawley rats.

Noise pollution remains a pervasive health hazard that people encounter especially in large commercial metropolis and has been implicated in many adverse non-auditory health conditions such as hypertension, atherosclerosis, vascular (endothelial) dysfunction and metabolic disorders. There is a growing body of evidence showing that chronic noise exposure is associated with an increased risk of hypercholesterol, adiposity and development of type 2 diabetes. The present study investigated the effect of noise stress on parameters of glucose homeostasis in male rats and possible recovery after noise cessation. Twenty-four (24) adult male Sprague-Dawley rats were designated into four groups (n = 6 per group). All rats except the control group were exposed to 95dB noise using a noise generator for 28 consecutive days. A group of rats was investigated immediately after 28 days of noise exposure (NE28), while others were left to recover from noise stress for 7 days (NER7) or 14 days (NER14). OGTT and ITT were performed using standard methods. Plasma levels of triglyceride (TRIG), total cholesterol (CHOL), low density lipoprotein (LDL) and high-density lipoprotein (HDL) were determined. Serum level of insulin, corticosterone (CORT) and corticosterone-releasing-factor (CRF) were determined using ELISA. Homeostasis model assessment-insulin resistance (HOMA-IR) and glycogen content in liver as well as gastrocnemius muscle were also determined. Although glucose tolerance remained unchanged in the noise-exposed groups, insulin sensitivity was however significantly reduced compared with control. There was significant increase (P < 0.05) in the level of CHOL, LDL and HDL. Noise also increased (P < 0.05) both insulin and CORT levels; and elicited a higher HOMA-IR index in NE28 rats. Hepatic and myocytic glycogen content were lower (P < 0.05) in NE28 rats relative to control. The reported changes above were reversed following a 14-day noise withdrawal period. Noise-induced insulin resistance may result from dysregulation of the stress axis and appears to be reversible with noise cessation.

Dynamics of inflammatory reaction and oxidative stress across maternal serum, placenta and amniotic fluid in laboratory rats and the role played by genistein aglycone.

Background Genistein was reported to adversely influence fetal development although this is yet to be fully understood as a mechanism. Methods In this study, pregnant rats were divided into control (Cont.) and genistein force-fed (2-mg/kg and 4-mg/kg) groups. Each group was divided further into five subgroups: GD-0, GD-6, GD-13, GD-18, and GD-20 based on the terminal gestational day (GD). On the respective terminal GD, the rats were sacrificed and blood samples and amniotic fluid were carefully collected and separated and placenta homogenates were prepared. These samples were evaluated for oxidative stress and inflammatory reaction. The weights of embryonic implant and placenta tissue were also recorded. Heat shock protein (Hsp) (60 and 90), corticosterone, and oxidative stress biomarkers were determined in all the samples. Results Fetal and placental weights in all genistein-exposed groups were significantly decreased. A fluctuation in the level of the Hsp was recorded with a significant decrease recorded in Hsp90 level in the placenta and amniotic fluid towards GD-20 along with a concomitant increase in the corticosterone level in the amniotic fluid in all genistein groups compared to control. Maternal serum at GD-18 and GD -20 recorded a significant increase in antioxidant level (SOD, GSH, CAT) in all genistein-exposed groups. However, these antioxidants were significantly reduced in the placenta and the amniotic fluid compared to control. Conclusions Genistein enhances the placenta function in attenuating the risk of oxidative stress in the amniotic fluid and deferentially suppressed inflammatory activities in the placenta during early gestation and towards late gestation period.

Glucometabolic effects of single and repeated exposure to forced-swimming stressor in Sprague-Dawley rats.

OBJECTIVES: We aimed to evaluate the effects of a single (acute) and repeated (chronic) exposure to forced-swimming stressor on glucose tolerance, insulin sensitivity, lipid profile and glycogen content in male rats. METHODS: Thirty adult male Sprague-Dawley rats (12 weeks old) were divided randomly into five groups: control group, single exposure (SE) to forced-swim stressor, repeated exposure to forced-swim stressor for 7 days (RE7), 14 days (RE14) and 28 days (RE28). Glucose tolerance test and Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) were undertaken on fasting rats to obtain glucose and insulin profiles. ELISA was performed to assess plasma insulin and corticosterone levels. Total cholesterol, triglyceride, high- and low-density lipoproteins, hepatic and skeletal glycogen content were also determined. RESULTS: Repeated exposure to stressor induced glucose intolerance and insulin resistance in the experimental rats. Results showed that all RE groups exhibited a significantly higher area under the curve compared with others (p=0.0001); similarly, HOMA-IR increased (p=0.0001) in all RE groups compared with control. Prolonged exposure to stressor significantly increased the plasma insulin and corticosterone levels but decreased the glycogen content in the liver and skeletal muscle when compared with the control group. Additionally, chronic stressor significantly increased the total cholesterol and triglyceride levels, however, acute stressor produced significantly elevated high-density lipoproteins level. CONCLUSIONS: In conclusion, repeated exposure to forced-swimming stressor induced glucose intolerance and insulin resistance in rats by disrupting the insulin sensitivity as well as heightening the glycogenolysis in the liver and skeletal muscle. Acute stressor was unable to cause glucose intolerance and insulin resistance but it appears that may have a positive effect on the lipid metabolism.

Magnesium upregulates insulin receptor and glucose transporter-4 in streptozotocin-nicotinamide-induced type-2 diabetic rats.

OBJECTIVE: We investigated the effects of magnesium supplementation on glucose tolerance, insulin sensitivity, oxidative stress as well as the concentration of insulin receptor and glucose transporter-4 in streptozotocin-nicotinamide induced type-2 diabetic (T2D) rats. METHODS: Rats were divided into four groups designated as: 1) control (CTR); 2) diabetic untreated (DU); 3) diabetic treated with 1 mg of Mg/kg diet (Mg1-D); and 4) diabetic treated with 2 mg of Mg/kg diet (Mg2-D). T2D was induced with a single intraperitoneal (i.p.) injection of freshly prepared streptozotocin (55 mg/kg) aft er an initial i.p. injection of nicotinamide (120 mg/kg). Glucose tolerance, insulin sensitivity, lipid profile, malondialdehyde (MAD) and glutathione content, insulin receptors (INSR) and glucose transporter-4 (GLUT4), fasting insulin and glucose levels were measured, and insulin resistance index was calculated using the homeostatic model assessment of insulin resistance (HOMA-IR). RESULTS: Magnesium supplementation improved glucose tolerance and lowered blood glucose levels almost to the normal range. We also recorded a noticeable increase in insulin sensitivity in Mg-D groups when compared with DU rats. Lipid perturbations associated T2D were significantly attenuated by magnesium supplementation. Fasting glucose level was comparable to control values in the Mg-D groups while the HOMA-IR index was significantly lower compared with the DU rats. Magnesium reduced MDA but increased glutathione concentrations compared with DU group. Moreover, INSR and GLUT4 levels were elevated following magnesium supplementation in T2D rats. CONCLUSION: These findings demonstrate that magnesium may mediate effective metabolic control by stimulating the antioxidant defense, and increased levels of INSR and GLUT4 in diabetic rats.

Role of amygdala kisspeptin in pubertal timing in female rats.

To investigate the mechanism by which maternal obesity disrupts reproductive function in offspring, we examined Kiss1 expression in the hypothalamic arcuate (ARC) and anteroventral periventricular (AVPV) nuclei, and posterodorsal medial amygdala (MePD) of pre-pubertal and young adult offspring. Sprague-Dawley rats were fed either a standard or energy-dense diet for six weeks prior to mating and throughout pregnancy and lactation. Male and female offspring were weaned onto normal diet on postnatal day (pnd) 21. Brains were collected on pnd 30 or 100 for qRT-PCR to determine Kiss1 mRNA levels. Maternal obesity increased Kiss1 mRNA expression in the MePD of pre-pubertal male and female offspring, whereas Kiss1 expression was not affected in the ARC or AVPV at this age. Maternal obesity reduced Kiss1 expression in all three brain regions of 3 month old female offspring, but only in MePD of males. The role of MePD kisspeptin on puberty, estrous cyclicity and preovulatory LH surges was assessed directly in a separate group of post-weanling and young adult female rats exposed to a normal diet throughout their life course. Bilateral intra-MePD cannulae connected to osmotic mini-pumps for delivery of kisspeptin receptor antagonist (Peptide 234 for 14 days) were chronically implanted on pnd 21 or 100. Antagonism of MePD kisspeptin delayed puberty onset, disrupted estrous cyclicity and reduced the incidence of LH surges. These data show that the MePD plays a key role in pubertal timing and ovulation and that maternal obesity may act via amygdala kisspeptin signaling to influence reproductive function in the offspring.

Restraint Stress Impairs Glucose Homeostasis Through Altered Insulin Signalling in Sprague-Dawley Rat.

The study investigated the potential alteration in the level of insulin and adiponectin, as well as the expression of insulin receptors (INSR) and glucose transporter 4 GLUT-4 in chronic restraint stress rats. Sprague-Dawley rats were randomly divided into two groups: the control group and stress group in which the rats were exposed to one of the four different restraint stressors; 1 h, twice daily for a period of 7 days (S7D), 14 days (S14D) and 28 days (S28D). Glucose tolerance and insulin sensitivity were evaluated following the final stress exposure. ELISA were performed to assess the level of insulin and adiponectin as well as expression of INSR and GLUT4 protein in skeletal muscle. Plasma corticosterone level was also determined as a marker of stress exposure. Restraint stress for 7 days caused transient glucose intolerance, while S14D rats demonstrated increased glucose intolerance and insulin insensitivity. However, restraint stress for 28 days had no effect on glucose tolerance, but did cause an increase in glucose response to insulin challenge. The serum level of adiponectin was significantly (p< 0.05) lower compared with the control value while insulin remained unchanged except at in S28D rats that had a significant (p<0.05) increase. The expression of INSR and GLUT4 receptors were significantly (p< 0.05) decreased in the skeletal muscle of restraint stress exposed rats. There was a significant (p< 0.05) increase in the plasma corticosterone level of the stress rats compared with their control counterparts. Restraint stress caused glucose intolerance and insulin insensitivity in male Sprague-Dawley rats, which becomes accommodated with prolonged exposure and was likely related to the blunted insulin signalling in skeletal muscle.

Testosterone promotes glucose intolerance, lipid disorder and oxidative stress in type 1 diabetic rats.

BACKGROUND: A bidirectional relationship has been established between testosterone deficiency (TD) and type 2 diabetes mellitus (T2DM). Low testosterone level has been reported to be a predisposing factor to T2DM, whereas recent clinical studies have shown a high prevalence of low testosterone in diabetic individuals. However, it is not known if any relationship exists between type 1 diabetes mellitus (T1DM) and testosterone level. This study was designed to investigate the effects of TD on T1DM. Twenty-four Sprague-Dawley rats were randomly divided into four groups designated as control, diabetic, orchiectomized and orchiectomized-diabetic. METHODS: Diabetes was induced with an intravenous injection of alloxan, and orchiectomy was done under sterile conditions. Fasting blood glucose (FBG), insulin level, lipid and oxidative parameters were determined in all experimental rats. RESULTS: The area under the curve during oral glucose tolerance test showed that the orchiectomized-diabetic group expressed an enhanced ability to metabolize glucose than the diabetic group. The malondialdehyde level in the diabetic group was significantly higher compared with that in the control and orchiectomized groups. Moreover, there was a significant decrease in glutathione (GSH) activity and an increase in superoxide dismutase activity in the diabetic group compared with control. Meanwhile, the activities of GSH and catalase were significantly reduced in the orchiectomized as well as the orchiectomized-diabetic group when compared with both control and diabetic groups. CONCLUSIONS: These data indicate that TD attenuates glucose intolerance under diabetic conditions and is equally associated with a considerable reduction in oxidative stress, which implies that testosterone may be a pro-oxidant.

Reproductive parameters and oxidative stress status of male rats fed with low and high salt diet.

BACKGROUND: Deficiency of minerals and micronutrients has been reported to impair the process of spermatogenesis. Historically, salt has been used by women on their husbands to increase their libido, however, the role of salt diet on sperm parameters are yet to be ascertained. AIM: The present study was designed to determine the effect of low and high salt diet on sperm parameters, oxidative status and reproductive hormone levels of male rats. MATERIALS AND METHODS: A total of 18 rats were divided into three groups: Group I: (control) received 0.3% salt diet, Group II: low salt (received 0.14% salt diet) and Group III: high salt (received 8% salt diet). All animals were treated for 6 weeks; after which epididymal sperm parameters; oxidative stress markers (malondialdehyde, glutathione, catalase and superoxide dismutase) in the testes and epididymal tissues, as well as follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone levels were determined. RESULTS: The results showed decreased sperm count in the low salt diet rats while increased sperm count was observed in the high salt diet treated rats. Both low salt and high salt diet fed rats exhibited increased abnormal sperm cells and increased epididymal oxidative stress when compared with their respective control. FSH and testosterone levels were increased in the high salt fed rats while LH level was decreased when compared with the control values. CONCLUSION: This study suggests that both low and high salt diet play a negative role in the fertility of male rats.

Calcium antagonists modulate oxidative stress and acrosomal reaction in rat spermatozoa.

INTRODUCTION: Calcium ions are vital in many biological processes and qualify as an almost ubiquitous intracellular second messenger. This indicates the multiplicity of the effects associated with drug actions aimed at interfering with calcium ions. To examine the cellular process involved in the induction of infertility in males by calcium antagonist (CA) even in the presence of normal semen parameters, we studied the effects of different CA namely; nifedipine, verapamil and diltiazem on oxidative balance and acrosome reaction in the sperm. MATERIAL AND METHODS: For this purpose, lipid peroxidation, antioxidants such as superoxide dismutase, catalase and reduced glutathione, and acrosomal reaction were determined in sperm samples of rats. RESULTS: Calcium antagonist causes significant oxidative stress in the epididymal sperm with increased malondialdehyde level and a concomitant decrease in antioxidant activities of catalase and superoxide dismutase. The percentage value of acrosomal-reacted sperm in the nifedipine, verapamil and diltiazem-treated rats were 41 ±2.45, 39 ±2.92 and 42 ±1.22 respectively, compared with the control group value of 86 ±2.92. CONCLUSIONS: It appears CA oxidatively modify the sperm resulting in functional inhibition of acrosomal reaction. Suppression of the sperm acrosomal reaction is known to have serious adverse implications for fertilization.

Antireproductive effect of calcium channel blockers on male rats.

INTRODUCTION: Drugs have been shown to adversely affect male fertility and recently anti-hypertensive drugs were added to the list. The anti-fertility effects of nifedipine and similar calcium channel blockers are well-illustrated in in vitro experiments but not in vivo. PURPOSE: The present study was designed to experimentally elucidate the sub-chronic effect of nifedipine, verapamil and diltiazem on sperm functions and reproductive hormone levels in vivo. METHODS: Male rats (150-200 g) were divided into four groups of ten rats each. Group 1 (control) received distilled water; Group 2 received nifedipine 0.57 mg/kg BW; Group 3 were given verapamil 3.40 mg/kg BW and Group 4 were given diltiazem 2.57 mg/kg BW. Each drug-treated group had its own recovery group from which treatment was discontinued for 30 days before the animals were sacrificed. Blood samples were collected for hormonal assay of FSH, LH and testosterone. Semen evaluation was done and the testes, seminal vesicle, epididymis and prostate were removed, and weighed immediately. RESULTS: Nifedipine, verapamil and diltiazem significantly decreased (P < 0.05) sperm count and motility in drug treated groups. The weight of the epididymis was significantly reduced (P < 0.05) in the drug treated rats. Semen parameters and other associated changes were restored after 30 days of drug withdrawal. CONCLUSION: Calcium channel blockers appear to have a reversible anti-fertility effect on male rats which does not occur through inhibition of the pituitary-gonadal axis.

Effect of methanol extract of Ricinus communis seed on reproduction of male rats.

AIM: To investigate the effect of methanol extract of Ricinus communis seed (RCE) on male rats reproductive functions. METHODS: Thirty-two male albino rats were divided into four groups. Groups 1, 2 and 3 were gavaged with 0.2 mL of 2.5% tween 80 (RCE vehicle; control) or 20 mg/(kg x d) and 40 mg/(kg x d) of RCE, respectively, for 30 days, and group 4 was also gavaged with 40 mg/(kg x d) of RCE, but was allowed a recovery period of 30 days. Five untreated female rats were cohabited with male rats in each group from day 25 of RCE treatment for 5 days, except group 4, where cohabitation began on day 25 of the recovery period. All male rats were sacrificed 24 h after the experiments. The female rats were laparotomized on day 19 of pregnancy and the number and weight of litters were recorded. RESULTS: There was a significant decrease (P<0.01) in the weight of the reproductive organs, sperm functions and serum levels of testosterone in RCE treated rats. There was disorganization in the cytoarchitecture of the testes, disruption of the seminiferous tubules and erosion of the germinal epithelium. The number and weight of litters of rats in groups 2 and 4 decreased significantly (P<0.05) but no changes were observed in group 3. RCE caused no changes in liver, kidney, heart or body weights in male rats. CONCLUSION: RCE has a reversible negative impact on male reproductive functions, which appears to be mediated via gonadal disruption in testosterone secretion.