Implantation and pregnancy outcome of Sprague-Dawley rats exposed to pirimiphos-methyl.

OBJECTIVE: This study was designed to investigate the effect of sublethal doses (10, 60, and 120 mg/kg of pirimiphos-methyl on implantation and pregnancy in female Sprague-Dawley rats. Pirimiphos-methyl is a pesticide widely used worldwide, especially in Africa to protect food against pests and has gained widespread acceptance. METHODS: Pregnant Sprague-Dawley rats used for this study had access to food and water ad libitum and were divided into a control group and three experimental groups based on dose of chemical given. The pregnant rats were given pirimiphos-methyl orally on days 1-5, 1-7, 7-18th day of gestation and from day 1 to term. Implantation studies were carried out on days 6 and 8 of pregnancy, while the fetal parameters were ascertained on day 19 of pregnancy and at term. Serum levels of progesterone and estradiol were measured on days 6, 8 and 19 of pregnancy. RESULTS: Sublethal administration of pirimiphos-methyl showed decreased number of implantation sites on days 6 and 8, fetal weight, crown-to-rump length, length of umbilical cord and placenta weight (day 19), birth weight, litter size and total number (at term) in rats administered with pirimiphos-methyl when compared with control. CONCLUSION: Administration of pirimiphos-methyl resulted in a reduced implantation rate due to decreased uterine receptivity caused by an imbalance in the level of estradiol and progesterone and impaired reproductive outcome during pregnancy.

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.

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.

Mechanism of delayed puberty in rats whose mothers consumed Hibiscus sabdariffa during lactation.

CONTEXT: Extract of the calyx of Hibiscus sabdariffa Linn. (HS) (Malvaceae) has been reported to decrease fluid and food intake in lactating rats through a mechanism not yet fully understood. It has also been reported that rat pups undernourished during lactation have delayed puberty onset, suggesting a link between nutrition and onset of puberty. There is paucity of data addressing the effect of maternal consumption of HS during lactation on the onset of puberty in the female offspring. OBJECTIVE: The present study was designed to investigate whether consumption of HS during lactation will affect the onset of puberty and to examine the possible mechanism underlying this. MATERIALS AND METHODS: Lactating Sprague-Dawley rats were randomly grouped into three on postnatal day one. One group had tap water (control); another had 0.6 g aqueous HS extract/100 mL, while the third had 1.8 g aqueous HS extract/100 mL as their drinking solution throughout lactation. Maternal fluid consumption, food consumption, weight gain, plasma Na(+) and corticosterone concentrations were determined. Offspring weights were recorded at 0, 21, 28, 35, and 42 days. Ages at onset of puberty and body weights were also recorded. RESULTS: A decreased maternal fluid and food intake and an increased maternal plasma Na(+) and corticosterone concentration were observed in HS dams. The HS treated female offspring showed delayed onset of puberty. DISCUSSION AND CONCLUSION: The accelerated growth and delayed puberty in the HS offspring may be through increased corticosterone and decreased leptin delivery through breast milk.

Fasting plasma glucose and cholesterol levels in pregnant Nigerian women.

There are numerous reports of altered carbohydrate metabolism in pregnancy. Normal pregnancy is sometimes characterised by mild fasting hypoglycaemia, postprandial hyperglycaemia and hyperinsulinaemia. Pregnancy has also been observed to be associated with a hypercholesterolaemic state in some individuals with pregnancy-induced hypertension. The aim of the present study was to assess the fasting plasma levels of glucose and cholesterol in pregnant Nigerian women, and to find out any differences from previously reported observations. Twenty pregnant consenting females were used for the study while twenty non-pregnant females were used as controls. Blood samples were taken from each subject after an overnight fast, and assayed for plasma glucose and cholesterol. Results obtained showed a decrease in fasting plasma glucose (from 3.96 mmo1/L to 3.12 mmo1/L) in early pregnancy (p < 0.05) but no change in late pregnancy. Plasma cholesterol was significantly higher (p < 0.05) in pregnant subjects (3.89 mmo1/L) than in the non-pregnant (2.40 mmo1/L), the increase being more appreciable in early pregnancy. These results are similar to data from non-African blacks and Caucasians.