leptin and estradiol-3-benzoate

To evaluate multiple follicular development synchronization after estrogen stimulation in prepubertal mice, follicular responsiveness to gonadotropin superovulation, the prospective reproductive potential and ovarian polycystic ovary syndrome (PCOS)-like symptoms at adulthood, prepubertal mice were intraperitoneally injected with estrogen to establish an animal model with solvent as control. When synchronized tertiary follicles in ovaries, in vitro oocyte maturation and fertilization rates, blastocyst formation rate, developmental potential into offspring by embryo transfer, adult fertility and PCOS-like symptoms, and involved molecular mechanisms were focused, it was found that estrogen stimulation (10 μg/gBW) leads to follicular development synchronization at the early tertiary stage in prepubertal mice; reproduction from oocytes to offspring could be realized by means of the artificial reproductive technology though the model mice lost their natural fertility when they were reared to adulthood; and typical symptoms of PCOS, except changes in inflammatory pathways, were not remained up to adulthood. So in conclusion, estrogen can lead to synchronization in follicular development in prepubertal mice, but does not affect reproductive outcome of oocytes, and no typical symptoms of PCOS remained at adulthood despite changes related to inflammation.

Topics: Animals; Estradiol; Female; Fertility; Insulin; Leptin; Mice; Ovarian Follicle; Ovary; Ovulation Induction; Pregnancy; Pregnancy Rate; Progesterone; Superovulation; Testosterone

In this study, 53 crossbred beef heifers were used to test the hypotheses that administration of exogenous FSH 2 days following CIDR insertion and administration of estradiol would increase the pregnancy rate in heifers synchronized for FTAI and that plasma leptin concentrations in beef heifers would be higher for heifers that became pregnant to FTAI. The heifers used in this study had a median age of 440 days, an average weight of 324 kg, an average body condition score of 5.1 and a mean reproductive tract score of 3.1. Heifers were stratified by weight and BCS into two groups and then treatments were randomly allotted to each group: (1) control (n=28) or (2) FSH (n=27). Both groups were administered 200mg estradiol benzoate (EB) and received an intravaginal controlled internal drug-releasing device (CIDR) on day 0. On day 2, females in the FSH treatment group were administered 20 mg of FSH, while the control group received 1 ml of saline. On day 7 all females were administered 25 μg PGF2α and the CIDR was removed. Then 24h following CIDR removal all females were administered 1mg EB and 24h later were subjected to FTAI. Pregnancy diagnosis was performed via transrectal ultrasonography 43 days following insemination. Blood samples were collected via jugular venipuncture on days 2, 6-10, 13 and 52 and plasma leptin concentrations were determined by radioimmunoassay. Pregnancy rates were higher (P=0.01) for FSH-treated females (60%) compared with females not receiving FSH (25%). Circulating plasma leptin concentrations were higher (P=0.0051) for pregnant females compared with females that did not become pregnant following FTAI during the experiment. Mean plasma leptin concentration was also higher (P=0.04) from day 2 to day 9 during the synchronization protocol in heifers that became pregnant compared with heifers that did not become pregnant from FTAI. There was no difference (P=0.38) in reproductive tract scores for heifers that became pregnant compared with heifers that did not become pregnant from FTAI. Circulating leptin concentrations were not different (P=0.11) for females receiving FSH compared with females in the non FSH-treated group. Circulating leptin concentrations were affected by sampling day (P<0.0001). However, there was no interaction between sampling day and pregnancy status (P=0.80), treatment and pregnancy status (P=0.14) or treatment and sampling day (P=0.12). These results indicate that the administration of FSH on day 2 of the synchr

Topics: Animals; Cattle; Dinoprost; Estradiol; Estrus Synchronization; Female; Follicle Stimulating Hormone; Insemination, Artificial; Least-Squares Analysis; Leptin; Pregnancy; Random Allocation

We evaluated the interplay among estrogen, leptin and thyroid function in the regulation of body mass in female rats. Adult female rats were divided into four groups: control (C, sham-operated), ovariectomized (OVX), ovariectomized treated with estradiol benzoate (Eb) 0.7 or 14microg/100gbw per day, during 21 days. OVX led to an increase in body mass, food intake and food efficiency (change in body mass as function of the amount of food ingested) which were normalized by the lower Eb dose, and decreased significantly when the higher dose was given. Serum leptin levels were increased more than two-fold in all ovariectomized groups. Serum T4 levels of the Eb treated OVX were significantly lower than in the controls. Serum T3 and TSH were unaffected by OVX or by Eb treatment. Uterine type 2 iodothyronine deiodinase (D2) activity changed in parallel with serum estradiol: decreased after OVX, returned to control levels after the lower E2 treatment, and increased significantly after the high Eb dosage. The hypothalamic D2 activity was reduced around 30% in all castrated groups, treated or not with estrogen, whereas in the brown adipose tissue the enzyme was not changed. Interestingly, although estrogen-treated OVX rats had lower body weight, serum leptin was high, suggesting that estrogen increases leptin secretion. Our results show that estradiol is necessary for the hypothalamic action of leptin, since the increase in leptin levels observed in all ovariectomized rats was associated with a decrease in food intake and food efficiency only in the rats treated with estrogen.

Topics: Animals; Body Weight; Eating; Estradiol; Female; Leptin; Ovariectomy; Rats; Rats, Wistar; Thyroid Function Tests; Thyroid Gland; Thyroxine

Nutrient balance affects the resumption of ovarian cyclic activity following calving in dairy cattle. However, few data are available about the relationships between nutrient balance and expression of oestrus or conception. It was hypothesised that previously anoestrous cows that conceived to first insemination and cows that expressed oestrus at the subsequent expected return to oestrus would be less likely to be in negative energy balance (i.e. would have higher body condition score, higher glucose, insulin-like growth factor (IGF), leptin or insulin concentrations, and lower non-esterified fatty acids (NEFA), blood urea nitrogen (BUN), beta hydroxy butyrate (BOH) concentrations 12-15 days after insemination) than herd mates not conceiving or expressing oestrus. Anoestrous cows were treated with progesterone and oestradiol benzoate (Day 0 = end of treatment period) and retrospectively categorised as conceiving (n = 108) or not conceiving (n = 108) to insemination. A subset of cows not conceiving to insemination were categorised as expressing (n = 44) or not expressing (n = 44) oestrus between Days 14 and 28 after initial insemination. Cows conceiving had a lower NEFA concentration (P = 0.014) than non-conceiving cows. Cows subsequently detected in oestrus had higher body condition scores (P = 0.016), IGF concentrations (P = 0.008) and milk protein percentages (P = 0.038), and lower BOH concentrations (P = 0.018) than cows not expressing oestrus. No difference in concentrations of leptin, insulin, glucose, blood urea nitrogen or milk yield were found between cows conceiving or not conceiving and those detected in oestrus or not detected in oestrus (P > 0.1). It is concluded that some measures of metabolic status at the time of pregnancy recognition affects the probability of pregnancy and of subsequent expression of oestrus in those treated, anoestrous cows not conceiving.

Topics: Anestrus; Animal Nutritional Physiological Phenomena; Animals; Blood Glucose; Body Composition; Cattle; Energy Metabolism; Estradiol; Estrus; Fatty Acids, Nonesterified; Female; Fertilization; Insemination, Artificial; Insulin; Lactation; Leptin; Pregnancy; Progesterone; Retrospective Studies

In order to understand the mechanism of increasing body fat in perimenopausal and postmenopausal women, an ovariectomy-induced obesity model was used to study the role of leptin. In this investigation, a long-term study lasted for 13 weeks was conducted to monitoring the change of serum leptin level in rats after the loss of estrogen, and also to examine the influence of estrogen replacement. The results showed that three weeks after the removal of ovaries the body weight of Ovx rats was already significantly higher than the other two groups, and continued to gain more weight thereafter. Accompanying with the significant weight gain was the changes in the serum leptin levels. The leptin concentration declined gradually during the first half of experimental period, dropping down to an almost undetectable level at week 7 (0.216+/-0.132 ng/ml). Subsequently, its concentration began to elevate, and by the end of experiment leptin level was significantly higher (3.182+/-0.936 ng/ml) than the value before the operation (0.818+/-0.242 ng/ml). This fluctuation of serum leptin level caused by ovariectomy was eliminated by the replacement of estrogen. The present data indicate that ovariectomy-induced weight gain is caused by the early drop in leptin level. The later rise in leptin production is connected to the increased body weight probably originated from a reduced sensitivity in leptin signal.

Topics: Animals; Disease Models, Animal; Estradiol; Female; Humans; Leptin; Menopause; Obesity; Ovariectomy; Ovary; Proteins; Rats; Rats, Sprague-Dawley; Weight Gain

In humans, circulating concentrations of the hormone leptin, normalized to body fat mass, are significantly higher in females compared to males. This experiment was designed to determine whether the administration of exogenous androgen or estrogen would significantly alter the relationship between plasma leptin and fat mass in rats.. In the first experiment, plasma leptin and retroperitoneal and parametrial (female)/epididymal (male) adipose tissue expression of leptin mRNA were measured in five male and five female 9.5-week-old Sprague-Dawley rats. In a second experiment, gonadectomized 10.5-week-old female Sprague-Dawley rats received 1 or 2 weeks of daily intraperitoneal injections (in oil) of 750 mg testosterone propionate, 2.5 microg of estradiol benzoate or vehicle. At 0, 1, and 2 weeks, plasma concentrations of leptin, fat pad weight of parametrial and retroperitoneal fat pads, and leptin mRNA expression by Northern blot in retroperitoneal fat pads were determined. Daily weight and food intake of animals were monitored throughout the study.. Circulating leptin concentrations per unit of fat pad mass and leptin mRNA expression normalized to actin mRNA were higher in gonadally intact female compared to male rats. Compared to placebo, estrogen administration decreased food intake and body weight, but had no significant effect on leptin mRNA expression or on circulating leptin concentration. Testosterone administration increased body weight and decreased expression of leptin mRNA (only after 2 weeks), but did not change food intake or circulating leptin concentration.. Administration of estrogen did not affect either leptin expression or the circulating concentration of leptin. Administration of androgen decreased expression of leptin mRNA. However, even after 2 weeks of testosterone administration to gonadectomized females, plasma leptin concentration, corrected for fat pad weight, was higher in gonadectomized females than in intact males. Thus, sex steroid-associated changes in plasma leptin concentration and leptin mRNA expression are not sufficient to explain the observed sexual dimorphism in plasma leptin concentrations in rats.

Topics: Adipose Tissue; Aging; Animals; Blotting, Northern; Estradiol; Female; Gene Expression; Homeostasis; Leptin; Male; Ovariectomy; Rats; Rats, Sprague-Dawley; Retroperitoneal Space; RNA, Messenger; Sex Characteristics; Testosterone

Adipocyte hormone leptin (OB protein) is considered to be an "adiposity signal" regulating body weight homeostasis and energy balance. We have previously reported that oestrogens (oestradiol-benzoate) significantly decrease the body weight in male rats, increase anterior pituitary and serum levels of the intracellular messenger cAMP, which activates cAMP-dependent protein kinase A, their targets include hormone-sensitive lipase and they influence the brain sympathetic system. The present study tested our hypothesis that oestrogens could influence serum leptin levels in male mice. We found that chronic administration of oestradiol-benzoate significantly attenuated serum levels of leptin, in the dependence on the duration of its administration, and simultaneously decreased body weight. We suppose that oestrogens affect leptin levels interacting with the signal transmission system of cAMP, possibly at the genome level. Our observations that the food consumption of mice with simultaneously decreased body weight and levels of serum leptin support the idea that there exists a satiety factor that counters the effect of low leptin.

Topics: Adipocytes; Animals; Body Weight; Estradiol; Leptin; Male; Mice; Proteins