Leptin controls rabbit ovarian function in vivo and in vitro: Possible interrelationships with ghrelin

Association between blood hormones and fecundity in rabbit does

The aim of the present study was to examine the association between blood hormone level and fecundity in rabbit does. The ovulation of nulliparous New Zealand White rabbits was induced by administration of PMSG and LH-RH analogue. Next day, the does were inseminated, blood was collected and the plasma levels of IGFI, leptin, progesterone and estradiol were measured by radioimmunoassay. After the birth of pups, the retrospective comparison of level of hormones in the blood of fertile and non-fertile animals was performed. Fertile does had significantly higher blood level of IGF-I and lower concentration of leptin than the infertile ones. No significant differences in blood progesterone and estradiol level was found between fertile and non-fertile females. These observations suggest that blood IGF-I and leptin level could be useful for diagnostics and prediction of rabbit does' fecundity.

Changes in Body Reserves, Non-Esterified Fatty Acids, and Leptin during the Reproductive Lifespan of the Rabbit Female

The aim of this work is to study changes in body weight, perirenal fat thickness (PFT), and non-esterified fatty acid (NEFA) and leptin concentrations throughout the reproductive life of the rabbit female and their correlations when a semi-intensive reproductive rhythm is applied. A total of 46 lactating females were used. Body weight, PFT, and NEFA and leptin concentration were recorded at 12 weeks of age, at first mating and delivery, and at second, third, and fourth mating, 12th d of gestation, and delivery. The highest body weight was detected on the 12th d of any gestation, around 4280 g, and the lowest weight was at delivery, around 4030 g. PFT increased until third mating. NEFA and leptin concentration showed a cyclical pattern throughout the reproductive lifespan of the females. NEFAs presented the highest concentration at delivery within each reproductive cycle and levels decreased over the course of the deliveries (0.423 mmol/L at first delivery, 0.406 mmol/L at second delivery, 0.371 mmol/L at third delivery, and 0.309 mmol/L at fourth delivery). Similar NEFA concentrations at mating and on the 12th d of gestation were obtained. Leptin showed the highest concentrations at mating within each reproductive cycle. Leptin decreased between mating and delivery in all reproductive cycles and it was close to 1 ng/mL HE. Low or null correlations were shown between body weight, PFT, and NEFA and leptin concentration at mating, 12th d of gestation, and delivery. In conclusion, females are able to maintain a semi-intensive reproductive rhythm across four parities weighing around 4 kg from first mating. Females had an increased perirenal fat thickness until third delivery, and their NEFA concentration was maximum at delivery and leptin concentration was maximum at mating. Body weight, PFT, and NEFA and leptin concentration should be measured during critical moments of reproductive life in order to determine body condition and energy mobilization, due to their low or null correlations.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus-pituitary-gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

Effect of Fasting-Mimicking Diet or Continuous Energy Restriction on Weight Loss, Body Composition, and Appetite-Regulating Hormones Among Metabolically Healthy Women with Obesity: a Randomized Controlled, Parallel Trial

BACKGROUND

Fasting-mimicking diet (FMD) has been recently promoted to achieve similar metabolic changes of fasting. The purpose of our study was to compare the effect of FMD versus continuous energy restriction (CER) on anthropometric measurements, body composition, glucose metabolism, and serum levels of leptin, neuropeptide Y (NPY), and total ghrelin.

METHODS

A randomized controlled trial (RCT) was conducted on 60 women with obesity aged 18-55 years. Subjects received either a 5-day FMD (low in energy, sugars, and proteins, but high in unsaturated fats) or a CER (an average daily energy deficit of 500 kcal) for 2 months. Anthropometric and biochemical factors were measured at baseline and the end of the study. Serum levels of leptin, total ghrelin, and NPY were tested with an ELISA kit. Physical activity and dietary intakes were also recorded.

RESULTS

There was no significant difference in weight loss between the two groups: mean weight change for CER was - 2.29 (standard deviation [SD], 1.95) kg compared to - 1.13 (2.27) kg for FMD (p = 0.06). There was more reduction in the basal metabolic rate (BMR) in the CER group (p = 0.045). Favorable effects on fat mass and muscle mass were only seen in the FMD group. Although insulin resistance was reduced in the FMD group compared to the CER group, results were not significant after adjustment. After controlling for potential confounders, there was a significant increase in serum levels of total ghrelin (p = 0.048) and NPY (p = 0.041) following CER; however, results for circulating leptin were not statistically significant (p = 0.48).

CONCLUSIONS

There was no significant difference in weight loss following FMD and CER. However, FMD was more effective at reducing insulin resistance and regulating appetite-regulating hormones as well as preserving muscle mass and BMR.

TRIAL REGISTRATION

This trial was registered at the Iranian Clinical Trial Registry ( https://www.irct.ir/trial/40881 ) with the IRCT identification number IRCT20190717044244N1.

Relationship between body conditions and environmental contaminants in bovine ovarian cells

The effect of body condition and environmental contaminants on reproductive processes is known; however, it is not known whether basic ovarian cell functions and their response to these contaminants depend on body condition. This study aimed to understand the interrelationships between body conditions and environmental contaminants on ovarian cells. For this purpose, we compared ovarian granulosa cells isolated from cows with an emaciation tendency (body condition score, BCS2 on a scale from 1 to 5) and cows with average body condition (BCS3); proliferation, apoptosis, secretory activity and the response to environmental contaminants were all assessed in the cells. In the 1st series of experiments, ovarian granulosa cells isolated from BCS2 and BCS3 cows were cultured with and without benzene, xylene, and toluene (0.1%). The accumulation of nuclear and cytoplasmic markers of apoptosis (p53 and bax, respectively), a proliferation marker (PCNA), progesterone (P4), and insulin-like growth factor I (IGF-I) was evaluated by Western blot and radioimmunoassay (RIA) experiments. In the 2nd series of experiments, the groups of granulosa cells were cultured with and without mycotoxine deoxynivalenol (DON, 0, 10, 100, or 1000 ng/ml). The secretion of P4 and testosterone (T) was measured by RIA. In comparison to cells from BCS2 animals, ovarian cells isolated from BCS3 cows accumulated higher levels of bax and PCNA but not p53, and they secreted higher amounts of IGF-I but not P4 or T. In cells from BCS2 animals, benzene and xylene promoted p53 accumulation, and toluene reduced the accumulation. In the BCS2 group, all treatments promoted bax and PCNA expression. However, in cells from BCS3 animals, all environmental pollutants inhibited p53, toluene inhibited PCNA but not bax, and xylene did not affect the expression of proliferation or apoptosis markers. In the BCS2 group, P4 was inhibited by xylene, and IGF-I was stimulated by xylene but not by benzene or toluene. Low-dose exposure to DON (10 ng/ml) promoted P4 release from cells from both BCS2 and BCS3 animals, but high-dose exposure to DON (1000 ng/ml) reduced P4 secretion from the cells from BCS2 animals but not from the cells from BCS3 animals. The release of T was inhibited by high-dose exposure to DON (1000 ng/ml), irrespective of the BCS. An emaciation tendency reduces proliferation, apoptosis, and IGF-I release, and it induces or reverses the action of environmental contaminants on ovarian functions. Taken together, these observations demonstrate the effect of body condition and the direct influence of environmental contaminants on basic bovine ovarian functions. Furthermore, they demonstrate for the first time that the response of ovarian cells to environmental contaminants can be regulated by cow body condition.

Leptin induced in vitro development of ovarian follicles in sheep is related to the expression of P450 aromatase and steroidogenesis

The objective of this study was to test the hypothesis that Leptin induced in vitro growth in preantral follicles in sheep involves modulation of P450 aromatase expression and steroidogenesis. Accordingly, the expression of P450 aromatase gene was studied in the cumulus cells and oocytes isolated from different stages of preantral follicles (PFs') grown in vivo, cultured in TCM 199B, TCM 199B + Leptin (10 ng/ml) (TCM199BL) or a standard PF culture medium supplemented with Leptin (10 ng/ml) (SML). Ovarian follicles grown in vivo or in SML expressed P450 aromatase both in cumulus cells and oocytes at all the development stages. In the oocytes from PFs' grown in vitro, P450 expression was consistently lower than in those from in vivo grown follicles at all except the preantral stage. The patterns of expression of aromatase gene in the cumulus cells from in vivo grown and the PFs' cultured in TCM 199BL were similar. Significantly higher levels of progesterone production were supported by SML at all the development stages than the other two media. Oestradiol concentration in the spent TCM 199B and SML showed a significant increase as the development progressed from preantral to large antral stage. However, such increase was not sustained beyond early antral stage in the PFs' cultured in TCM199BL. It is concluded that Leptin modulates the expression P450 aromatase while supporting the in vitro development of the ovarian follicles in sheep.

Apoptosis signal-regulating kinase (ASK-1) controls ovarian cell functions

The involvement of the apoptosis signal-regulating kinase 1 (ASK1)-related signalling pathway in the control of reproduction is unknown. This study aimed to investigate the role of ASK-1 in the control of basic ovarian functions (proliferation, apoptosis and hormone release) and its response to ovarian hormonal regulators (leptin and FSH). We compared the accumulation of ASK-1, proliferation marker proliferating cell nuclear antigen (PCNA), apoptosis marker Bax and apoptosis and proliferation regulating transcription factor p53 and the release of progesterone (P4), oxytocin (OT), insulin-like growth factor I (IGF-I) and prostaglandins F (PGF) and E (PGE) using cultured porcine ovarian granulosa cells transfected with ASK-1 cDNA and cultured with leptin or FSH. This study is the first to demonstrate that ASK-1 does not affect cell apoptosis and viability in ovarian cells, but promotes cell proliferation, suppresses p53, alters the release of ovarian hormones (P4, OT, IGF-I, PGF and PGE) and defines their response to the upstream hormonal regulators leptin and FSH. Therefore, ASK-1 can be considered a new and important regulator of multiple ovarian functions.

Mojave Yucca (Yucca Schidigera Roezl) Effects on Female Reproduction a Review

Yucca is an important source of biologically active substances such as steroidal saponins and stilbenes providing many beneficial effects when administered to humans and other animals. These substances offer a great potential in the prevention and treatment of current civilized diseases as well as to their: antioxidant, hypocholesterolaemic, anti-inflammatory, phytoestrogenic, pro-apoptotic, anti-proliferative, and anti-carcinogenic properties. This review focuses on the roles of two main yucca constituent groups and their ability to modulate ovarian functions and female reproductive performance. Both the biological activity of yucca substances and the mechanisms of their actions on ovaries are still incompletely understood. Thus, the direct effects of yucca extract on ovarian cells in animal models under in vitro conditions, as well as actions after yucca consumption will be discussed.

Modulatory role of leptin on ovarian functions in water buffalo (Bubalus bubalis)

The aim of the present study was to demonstrate the modulatory role of leptin on bubaline granulosa cells (GCs) and luteal cells (LCs) functions using an in vitro cell culture system and to establish a cross talk between leptin and insulin-like growth factor-1 (IGF-1). GCs were collected from group IV follicles (>13 mm size) and LCs from mid-luteal phase corpus luteum and were grown in serum-containing media supplemented with leptin at three different dose rates (0.1, 1, and 10 ng/mL) and time durations (24, 48, and 72 hours). We evaluated the production and secretion of estradiol (E2) and progesterone (P4) using RIA and the mRNA expression of steroidogenic acute regulatory protein (STARD1), cytochrome P450 cholesterol side-chain cleavage (CYP11A1), 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome P450 aromatase (CYP19A1), sterol regulatory element-binding protein 1 (SREBP1), steroidogenic factor-1 (SF1), anti-apoptotic gene PCNA, pro-apoptotic gene caspase 3 and endothelial cell marker, Von Willebrand factor (vWF), using quantitative real-time polymerase chain reaction. The results depicted a direct inhibitory action of leptin on GCs steroidogenesis in a time-dependent manner (P < 0.05), whereas in the presence of IGF-1 the inhibitory effect was reverted. Furthermore, leptin augmented both cellular proliferation (PCNA) and apoptosis (caspase 3). On the other hand, in LCs, leptin alone showed an apparent stimulatory effect on steroidogenesis (P < 0.05); however, in the presence of IGF-1, an antagonistic effect was witnessed. Moreover, leptin had an inhibitory effect on apoptosis while promoted cellular proliferation and angiogenesis. These findings were further strengthened by immunocytochemistry. To conclude, these observations for the first time reported that in buffaloes leptin has a direct dose-, time-, and tissue-dependent effect on ovarian steroidogenesis, angiogenesis, and cytoprotection, and furthermore, it can regulate the effect of systemic factors like IGF-1. Hence, this in vitro study provides an insight into the putative roles of leptin alone and its interactions in vivo.

Role of leptin receptors in granulosa cells during ovulation

Leptin is an important hormone influencing reproductive function. However, the mechanisms underpinning the role of leptin in the regulation of reproduction remain to be completely deciphered. In this study, our objective is to understand the mechanisms regulating the expression of leptin receptor (Lepr) and its role in ovarian granulosa cells during ovulation. First, granulosa cells were collected from superovulated mice to profile mRNA expression of Lepr isoforms (LeprA and LeprB) throughout follicular development. Expression of LeprA and LeprB was dramatically induced in the granulosa cells of ovulating follicles at 4 h after human chorionic gonadotropin (hCG) treatment. Relative abundance of both mRNA and protein of CCAAT/enhancer-binding protein β (Cebpβ) increased in granulosa cells from 1 to 7 h post-hCG. Furthermore, chromatin immunoprecipitation assay confirmed the recruitment of Cebpβ to Lepr promoter. Thus, hCG-induced transcription of Lepr appears to be regulated by Cebpβ, which led us to hypothesise that Lepr may play a role during ovulation. To test this hypothesis, we used a recently developed pegylated superactive mouse leptin antagonist (PEG-SMLA) to inhibit Lepr signalling during ovulation. I.p. administration of PEG-SMLA (10 μg/g) to superovulated mice reduced ovulation rate by 65% compared with control treatment. Although the maturation stage of the ovulated oocytes remained unaltered, ovulation genes Ptgs2 and Has2 were downregulated in PEG-SMLA-treated mice compared with control mice. These results demonstrate that Lepr is dramatically induced in the granulosa cells of ovulating follicles and this induction of Lepr expression requires the transcription factor Cebpβ. Lepr plays a critical role in the process of ovulation by regulating, at least in part, the expression of the important genes involved in the preovulatory maturation of follicles.

Leptin in farm animals: where are we and where can we go?

Fat affects meat quality, value and production efficiency as well as providing energy reserves for pregnancy and lactation in farm livestock. Leptin, the adipocyte product of the obese (ob) gene, was quickly seen as a predictor of body fat content in animals approaching slaughter and an aid to assessing reproductive readiness in females. Its participation in inflammation and immune responses that help animals survive infection and trauma has clear additional relevance to meat and milk production. Furthermore, almost a decade of discoveries of nucleotide polymorphisms in the leptin and leptin receptor genes has suggested useful applications relating to feed intake regulation, the efficiency of feed use, the composition of growth, the timing of puberty, mammogenesis and mammary gland function and fertility in cattle, pigs and poultry. The current review attempts to summarise where research has taken us in each of these aspects and speculates on where future research might lead.

Expression of SDF-1α and leptin, and their effect on expression of angiogenic factors in mouse ovaries

OBJECTIVE

Ovarian angiogenesis plays an important role in folliculogenesis. However, little is known about the expression of angiogenic factors during follicular development according to female age. Stromal cell derived factor-1α (SDF-1α) plays a role in granulosa cell survival and embryo quality as an angiogenic chemokine. Leptin is also involved in folliculogenesis and angiogenesis. This study examined expression of SDF-1α and leptin, and their effects on the expression of angiogenic factors in the ovary during follicular development according to female age.

METHODS

Ovaries were collected from C57BL mice of two age groups (6-9 weeks and 24-26 weeks) at 6, 12, 24, and 48 hours after 5 IU pregnant mare's serum gonadotropin (PMSG) injection. The expression of ovarian SDF-1α and leptin mRNA was evaluated by RT-PCR. In the organ culture experiment, the ovaries were cultured in transwell permeable supports with Waymouth's medium treated with various doses of SDF-1α (50-200 ng/mL) or leptin (0.01-1 µg/mL) for 7 days. Then, mRNA expression of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), and visfatin were examined in the cultured ovaries.

RESULTS

Expression of SDF-1α and leptin in the ovary was significantly lower in the aged mouse group compared to the young mouse group (p<0.05). Expression of these two factors increased with follicular development after PMSG administration. SDF-1α treatment stimulated visfatin expression in a dose-dependent manner, while leptin treatment significantly increased eNOS expression.

CONCLUSION

These results suggest that decrease of ovarian SDF-1α and leptin expression may be associated with aging-related reduction of ovarian function. SDF-1α and leptin may play a role in follicular development by regulating the expression of angiogenic factors in mouse ovaries.

Plasma leptin level in hyperlipidemic mares and their newborn foals

The aim of this study was to evaluate the relationship between plasma leptin and lipid levels in breeding mares and their newborn foals. The study was conducted on 17 Polish cold-blood mares and their newborn foals. The mares were divided into two groups, according to the course of delivery. These groups were seven mares which had a normal delivery and 10 mares which had required veterinary intervention during their delivery. Blood samples were taken from the jugular vein of both the mares and their foals. The blood samples were taken within 30 min after delivery, as well as on four successive mornings directly afterwards. In obtained plasma samples, the leptin, triacylglycerols (TG) and free fatty acid (FFA) concentrations were measured. The leptin and TG levels in the plasma sampled on the day of delivery and the two following days were significantly higher in mares which received veterinary intervention during the delivery, when compared to the results obtained from the plasma of mares which had normal delivery. The results obtained from foals did not show any statistical differences. In conclusion, the conducted tests have shown that post-parturient hyperlipidemia and hyperleptinemia in mares did not influence the lipid status and plasma leptin level in newborn foals.