Effects of lipopolysaccharide exposure at different postnatal time points on the response of LH to homotypic stress in adulthood

Early-life immune stress may have long-lasting effects, known as programming effects, on the physiological response to stress in adulthood. There may be a critical window after birth during which such a challenge can induce long-lasting alterations. However, there are few reports regarding the consequences of this phenomenon for later reproductive function. Here we report on induction by early-life LPS injection of long-lasting alterations in the adult LH response to homotypic immune stress in male rats. First, we investigated developmental changes in the LH response to LPS, since immune challenge during the stress hyporesponsive period can induce long-lasting effects on physiological functions. Rat serum LH concentrations were decreased by LPS (100 μg/kg) injection on postnatal day 15 or 25, but not day 10, suggesting that the period prior to postnatal day 10 is the stress hyporesponsive period for LH. Serum LH concentrations and body weight were decreased by adult LPS (400 μg/kg) injection in rats given saline or LPS (100 μg/kg) on postnatal day 25, but not in rats given LPS (100 μg/kg) on postnatal day 10. Expression of hypothalamic IL-1β and TNF-α mRNA, which suppress serum LH during immune stress, were equally increased in these groups by adult LPS (400 μg/kg) injection. The present data suggest that the period prior to postnatal day 10 is the critical window in which immune stress can induce long-lasting alterations in the LH response, but that IL-1β and TNF-α are not involved in mediating the altered response.     

Programmed hyperphagia due to reduced anorexigenic mechanisms in intrauterine growth-restricted offspring

Maternal food restriction during pregnancy results in intrauterine growth-restricted (IUGR) newborns with significantly decreased plasma leptin levels. When nursed by ad libitum-fed controls, IUGR offspring exhibit hyperphagia with adult obesity, marked by increased percentage body fat and plasma leptin, suggesting altered anorexigenic pathways. The authors examined leptin signaling pathways and food intake responses to 2 putative anorexic effectors (leptin and sibutramine, a serotonin reuptake inhibitor) in IUGR offspring. From 10 days to term gestation and through lactation, control pregnant rats received ad libitum food, whereas study rats were 50% food restricted. Following birth, litter size was standardized, and all offspring were nursed by control dams. At 3 weeks of age, offspring were weaned to ad libitum laboratory chow. At ages 1 day and 3 weeks, hypothalamic leptin receptor (Ob-Rb) mRNA and total STAT3 protein expression were determined. In addition, phosphorylated STAT3 was measured in 1-day-old offspring administered peripheral leptin. In prepubescent and adult offspring, anorexic effects of leptin and sibutramine were determined. At 1 day of age, IUGR pups showed increased hypothalamic Ob-Rb mRNA and total STAT3 protein expression though reduced leptin activated phosphorylated STAT3. At 3 weeks of age, IUGR offspring had decreased hypothalamic Ob-Rb mRNA expression, although with continued elevated STAT3 protein levels. The IUGR offspring demonstrated resistance to anorexigenic agents, leptin (6 weeks and 6 months), and sibutramine (8 months), as evidenced by less reduction in food intake and less body weight loss than controls. The IUGR offspring demonstrate suppressed leptin-induced STAT3 phosphorylation and impaired anorexigenic response to 2 factors in the central satiety pathway. This reduced anorexigenic function, together with normal or perhaps enhanced orexigenic function, contributes to the development of programmed obesity in IUGR rat offspring.     

Pituitary responsiveness to luteinizing-hormone-releasing hormone in different reproductive disorders. A review

As a result of the use of synthetic luteinizing-hormone-releasing hormone (LHRH) (and its analogs), significant advances in modern clinical practice are being realized. We studied the use of LHRH as a test for pituitary reserve for gonadotropin secretion in different reproductive disorders. Synthetic LHRH was used as a diagnostic test for discriminating pituitary from hypothalamic disorders. After appropriate LHRH priming of the pituitary, LHRH was used to document hypothalamic dysfunction in patients with Kallmann's syndrome who had normal gonadotropin responsiveness to LHRH. The gonadotropin responsiveness to 100 micrograms of LHRH was impaired or absent in patients with panhypopituitarism, craniopharyngiomas, hemochromatosis and acromegaly accompanied by abnormal lactation. In women with gonadal dysgenesis, the absence of gonadal steroid feedback exacerbated the pituitary responsiveness to LHRH. Women with hyperprolactinemia are also known to have a blunted gonadotropin response to endogenous and exogenous LHRH. An experimental rat model was developed in our laboratory to study the site of prolactin action on gonadotropin secretion. LHRH challenge tests during perphenazine-induced hyperprolactinemia in rats indicated that prolactin may decrease pituitary sensitivity to LHRH. Additional experiments indicated that the increased progesterone produced in these hyperprolactinemic (pseudopregnant) rats was probably responsible for the decreased pituitary responsiveness to LHRH. Further studies will be necessary to determine whether prolactin, which can alter ovarian steroidogenesis in vitro, interferes with ovulation directly in addition to affecting the hypothalamic-pituitary axis.     

Maternal N-acetyl-cysteine (NAC) protects the rat fetal brain from inflammatory cytokine responses to lipopolysaccharide (LPS)

Objective: Inflammatory cytokines, play a central role in the genesis of preterm parturition and fetal brain injury. Lipopolysaccharide (LPS) may activate cytokine pathways via induction of oxidative stress pathways. We hypothesized that enhanced maternal antioxidant activity may blunt fetal brain inflammatory responses to maternal LPS injection in pregnant rats. Methods: Pregnant Sprague-Dawley rats at 18 and 20 days gestation received intraperitoneal (ip) LPS injection and pre- and post-treatment with the antioxidant N-acetyl-cysteine (NAC) or saline. Six hours after the LPS injection, rats were sacrificed, interleukin (IL)-6 and IL-10 mRNA expression in the fetal brains was determined by real time polymerase chain reaction. Results: Maternal ip LPS induced significant increase in fetal brain IL-6 mRNA expression at E18 (3.1?±?0.6 vs 1.0?±?0.10 AU) and E20 (29.01?+?13.06 vs 0.95?+?0.05 AU; p?<?0.05) compared to Control, only at E20 maternal LPS induced increase in fetal brain IL-10 compared to control. NAC administered prior to and after LPS significantly reduced fetal brain IL-6 at E18 and E20 and IL-10 at E20. Conclusion: Maternal NAC can protect the fetal brain from inflammatory cytokine responses to maternal LPS injection. These results suggest that NAC may potentially protect fetus from inflammation-associated brain injury and potential long term sequelae.     

Leptin and reproduction: a review

OBJECTIVE: To review recent advances in understanding the role of leptin in the physiology and pathophysiology of reproduction, with a focus on relevant clinical situations. DESIGN: A MEDLINE computer search was performed to identify relevant articles. RESULT(S): Leptin, an adipocyte hormone important in regulating energy homeostasis, interacts with the reproductive axis at multiple sites, with stimulatory effects at the hypothalamus and pituitary and inhibitory actions at the gonads. More recently, leptin has been shown to play a role in other target reproductive organs, such as the endometrium, placenta, and mammary gland, with corresponding influences on important physiologic processes such as menstruation, pregnancy, and lactation. As a marker of whether nutritional stores are adequate, leptin may act in concert with gonadotropins and the growth hormone axis to initiate the complex process of puberty. Conditions in which nutritional status is suboptimal, such as eating disorders, exercise-induced amenorrhea, and functional hypothalamic amenorrhea, are associated with low serum leptin levels; and conditions with excess energy stores or metabolic disturbances, such as obesity and polycystic ovarian syndrome, often have elevated serum or follicular fluid leptin levels, raising the possibility that relative leptin deficiency or resistance may be at least partly responsible for the reproductive abnormalities that occur with these conditions. CONCLUSION(S): Leptin may act as the critical link between adipose tissue and the reproductive system, indicating whether adequate energy reserves are present for normal reproductive function. Future interventional studies involving leptin administration are expected to further clarify this role of leptin and may provide new therapeutic options for the reproductive dysfunction associated with states of relative leptin deficiency or resistance.     

Levetiracetam ameliorates ovarian function in streptozotocin-induced diabetic rats

Abstract

Diabetes mellitus can adversely affect gonadal function. In the present study, we aimed to investigate the protective effects and mechanism of action of levetiracetam (LEV) on the ovaries in a streptozotocin (STZ)-induced diabetes model in rats. Twenty-one adult female rats were assigned to three groups as control, diabetes group treated with 1?mL/kg/d saline (STZ?+?SP) and diabetes group treated with 600?mg/kg/d LEV (STZ?+?LEV). Following 4 weeks treatment, blood samples were collected for biochemical analysis and ovariectomy was performed for histopathological examination. Plasma anti-Mullerian hormone (AMH), glutathione and total anti-oxidant capacity values were significantly lower whereas lipid peroxides and transforming growth factor-β (TGF-β) values were significantly higher in STZ?+?SP group compared to control. LEV treatment successfully decreased lipid peroxidation and TGF-β levels, and also increased anti-oxidant parameters and AMH levels in diabetic rats. Saline-treated rats significantly displayed ovarian degeneration and decreased counts of follicles. However, treatment of diabetic rats with LEV effectively prevented the degenerative changes and follicle loss. Also, LEV suppressed ovarian nuclear factor-kappa B (NF-kB) immunoexpression in diabetic rats. Taken together, we propose that LEV can ameliorate the adverse effects of diabetes on ovarian function via decreasing NF-kB expression and oxidative stress and increasing anti-oxidant status in rats.     

Female obesity in life cycle

Adipose tissue undergoes aging process as other tissues and both of quantity and distribution of body fat vary with an older age. Obesity in which body fat accumulates excessively is also influenced by aging. For evaluation of obesity, Kaup's index was most correlated with the thickness of fat tissues. Waist hip ratio (WHR) increased with an older age. From the view point of menarche, a role of body fat in reproductive function was evaluated. Ratio of body fat to body weight in the menarcheal age was between 22 and 24%. The ratio of non-menarcheal girls was smaller than that of the menarcheal of the same age. A proper amount of body fat seemed to be necessary for onset of ovarian function to menstruate. On obesity in reproductive age, two topics were discussed. One was the mechanism of menstrual disorders in obese women, the other complications of pregnancy. Concerning the central mechanism of menstrual disorders, hypothalamic disorders cause overfeeding to obesity and gonadal dysfunction to menstrual disorders because feeding center and control center of gonadal system are located in hypothalamus. For the peripheral mechanism, accumulation of fat soluble steroid hormones in the fat tissue disturbs cyclic state of endocrine fluctuation, and extraglandular estrogen production from androgen by aromatase in adipose tissue causes hyperestrogenism. Besides, hyperandrogenism in obese women was stressed on for a causing factor of menstrual disorders in obesity. Hyperandrogenism of obese women with menstrual disorders was associated with high level of cortisol and was corrected by weight reduction to regularize menstrual cycle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of insulin on rat ovarian leptin expression by immunohistochemical staining

AIM: Leptin and insulin may interact in regulating ovarian steroid synthesis. The objective of this study was to investigate immunohistochemical staining of leptin in normal rat ovarian tissues and in rats treated with insulin and insulin plus human chorinoic gonadotropin (hCG). METHODS: Paraffin blocks of rat ovarian tissues from a previous study, in which 18 adult, female Wistar rats with an average weight of 250 g were divided into three groups to receive either saline solution, human insulin (2 U/day) or human insulin (2 U/day) plus hCG (4 U/day) for 4 weeks, were used in this study to compare the effects on leptin staining. The results were analysed using a semiquantitative scoring system, such as mild, moderate and strong. RESULTS: No staining was observed in granulosa cells and theca interna cells of normal ovarian tissues. Theca externa cells had mild staining intensity (+), corpus luteum had moderate (+ +) and stroma had mild (+) staining intensity. Histological structure was impaired in the insulin group, luteinized cells had mild staining, there was no difference in other cell groups. Only theca externa cells of the developing follicles were stained in insulin plus hCG group, luteinized cells again had mild staining. CONCLUSIONS: Besides damaging the rat ovarian structure, insulin reduced staining intensity of leptin in luteinized cells. Insulin may stimulate ovarian steroid synthesis not only through its own receptors, but also by acting on the leptin expression of these cells.     

The LH surge in humans: its mechanism and sex difference

There is a sex difference in the response to an estrogen challenge test in humans, but, unlike with rats, this sex difference is not permanently imprinted in the central nervous system. Estrogen is not only the important ovarian signal to trigger off the LH surge, but it also probably plays an important role in activating the positive estrogen feedback mechanism in humans. For an LH surge to occur, amplification of the hypothalamic signal (enhanced secretion of GnRH) as well as sensitization of the pituitary responsiveness to GnRH are required. It is unlikely that androgens per se are responsible for suppressing the positive estrogen feedback in humans and the possible role of another gonadal factor other than androgens remains speculative. The LH surge is a neuroendocrine phenomenon involved primarily in the process of ovulation and it is not correlated to sexual identity and orientation. Furthermore, how the hypothalamic-pituitary axis (HPA) responds to the estrogen challenge can be accounted for purely by its exposure to a different steroid milieu without reference to gender identity or sexual orientation of the subject.     

Ovariectomy changes the response to antidepressant drugs in tail suspension test in mice

Depressive symptoms are very frequent over a lifetime, especially for women. Menopause is a period of higher depressive vulnerability. There are suggestive data that estrogen deficiency may increase the susceptibility for depression. We studied whether a bilateral ovariectomy (OVX) modifies mice behaviors and antidepressant drug effects through tail suspension test (TST). We evaluated behavioral changes at 1 week, 2 weeks, and up to 2 months after OVX. The behavior responses to doxepin, paroxetine, and venlafaxine at 1 week, 2 weeks, and 2 months after OVX were evaluated. No obvious difference was detected on the duration of immobility among control group, sham group, and OVX group in the TST at 1 week and 2 weeks after OVX. But the duration of immobility of OVX group was distinctly longer than that of both control group and sham operation group at 2 months after OVX. At 1 and 2 weeks after OVX, only the antidepressant response to venlafaxine was observed, while response to paroxetine increased 2 months after OVX. Response to antidepressant drugs was strongly modified in OVX mice. The present results suggest that not all antidepressant drugs are appropriate for depression with estrogen deficiency.     

Leptin

Leptin, a central hunger-regulating metabolic hormone discovered in 1994, is important in regulating energy homeostasis and exerts its regulatory role also on other endocrine functions at hypothalamic, pituitary and gonadal levels. The leptin signaling pathway is complex and needs to be further elucidated. Several conditions, including changes in body weight, are associated with altered serum levels of leptin. Obesity presents with leptin resistance, a decreased sensitivity for endogenous leptin, resulting in elevated leptin levels. During times of malnutrition, low leptin levels correlate with cycle abnormalities, especially with amenorrhea. In animal models, there is experimental evidence that leptin deficiency is associated with infertility. Therefore, leptin is thought to mediate between adipose tissue and reproductive function. In addition to its effects on menstrual cyclicity and fertility, leptin is linked to the onset of puberty and to pregnancy-specific pathologies that include fetal growth restriction. Although a variety of studies support the significant interactions between leptin and the reproductive system, clarification of its exact pathophysiological role needs further studies. Even so, the determination of leptin is not currently a routine parameter to assess metabolic or reproductive function.     

Progesterone stimulates cardiac muscle protein synthesis via receptor-dependent pathway

OBJECTIVE: To examine the effect of ovarian hormones on the regulation of cardiac growth. DESIGN: Ovariectomized rat model with replacement of 17beta-estradiol (E(2)) and progesterone (P). SETTING: University research laboratory. PATIENT(S): Female Sprague-Dawley rats (7-8 weeks old). INTERVENTION(S): Rats were separated into five groups: [1] sham-operated (S; n = 6), [2] ovariectomized plus placebo (OVX; n = 8), [3] OVX plus 17beta-E(2) (OVX+E(2); n = 8), [4] OVX plus P (OVX+P; n = 8), and [5] OVX+E(2)+P (n = 7). MAIN OUTCOME MEASURE(S): Cardiac muscle protein synthesis rates, steroid hormone receptor protein expression, and plasma volume. RESULT(S): Cardiac protein synthesis was greater in OVX+P (mean +/- SE; 11.4 +/- 1.5% per day) rats compared with S (5.9 +/- 0.6%/day), OVX (6.9 +/- 0.5%/day), OVX+E(2) (5.2 +/- 0.4%/day), and OVX+E(2)+P (6.8 +/- 0.3%/day) groups. Treatment of OVX+P rats with the P receptor antagonist RU 486 (n = 9) reduced protein synthesis rates to control levels (7.5 +/- 0.5% per day), indicating that P regulates cardiac protein metabolism through a receptor-dependent pathway. Both P and estrogen receptors were found in cardiac tissue homogenates, suggesting the possibility of direct effects of ovarian hormones on the heart. Progesterone replacement had an additional effect of increasing plasma volume. Rats in the OVX+P group had a 20% greater plasma volume compared with animals in the S group (5.24 +/- 0.22 vs. 4.19 +/- 0.26 mL/100 g). This effect of P replacement to increase plasma volume was not blocked by RU 486 (5.01 +/- 0.24 mL/100 g), suggesting that volume expansion was not solely responsible for the effects of P on cardiac protein synthesis. CONCLUSION(S): Our findings indicate a role for ovarian hormones in the regulation of cardiac growth in female rats.     

Basal,endogenous leptin is metabolically active in newborn rat pups

Objective.?The adipocyte-derived hormone leptin regulates food intake and body weight via the activation of JAK-STAT pathway in mammalian adult hypothalamic neurons. To investigate whether endogenous leptin is metabolically active in newborn rat pups, the JAK-STAT leptin signaling pathway was analyzed following leptin antagonist challenge.

Methods.?One day old male control pups were injected with either (i) saline, (ii) leptin (10?μg/g, s.c; n?=?4), (iii) pegylated leptin antagonist (PEG-MLA, 20?μg/g, s.c, n?=?4), or (iv) leptin plus PEG-MLA. Hypothalamus was dissected from individual pups at 30, 45, and 60?min. Protein expression of ObR, STAT3, pSTAT3, and SOCS3 was analyzed by Western blot.

Results.?Leptin, but not PEG-MLA, produced a significant increase in hypothalamic pSTAT3 relative to saline treatment. Systemically administered PEG-MLA effectively blocks leptin signal induction of hypothalamic JAK-STAT signaling. The presence of PEG-MLA in combination with leptin attenuated the leptin-induced increase in pSTAT3.

Conclusions.?Thus, basal leptin levels are metabolically active in the newborn rats. These results brings new insights in considering the importance of endogenous leptin at birth, especially in low birth weight offspring who may be predisposed to altered neurogenesis and later obesity, and provide potential therapeutic strategies for programmed or diet-induced obesity.     

Male gender promotes an increased inflammatory response to lipopolysaccharide in umbilical vein blood

Objectives: To establish gender-specific differences in maternal and fetal immune response in healthy human fetuses at term. Methods: Forty-five women with elective caesarean sections for uncomplicated singleton pregnancies were recruited for two studies. Using a multiplex biomarker immunoassay system, unstimulated maternal and fetal plasma concentrations of interleukin (IL)-1β, IL-1ra, IL-6, IL-8, macrophage inflammatory protein (MIP)-1α, and tumor necrosis factor (TNF)-α were measured from one study population. Lipopolysaccharide (LPS)-stimulated cytokine response was measured in a second study. Results: There were no significant gender differences in either maternal or fetal unstimulated plasma cytokine concentrations, but concentrations of the proinflammatory cytokines IL-1β and IL-6 were significantly greater in male fetal LPS-stimulated samples than in female fetal samples. Conclusions: Blood of male fetuses mounts a larger pro-inflammatory response to lipopolysaccharide (LPS). This heightened response could be a critical pathway in promoting premature rupture of membranes (PPROM) and may be associated with life long differential gender response to infection.     

Basal leptin concentrations in women with normal and dysfunctional ovarian conditions.

OBJECTIVE: To determine whether leptin is involved in ovarian function. METHODS: Fasting serum samples were obtained from 20 women with normal menstrual cycles who were either obese or non-obese: 12 non-obese patients with polycystic ovary syndrome (PCOS), 8 obese patients with PCOS, 10 patients with stress-related hypothalamic amenorrhea, and 8 patients with weight loss-related hypothalamic amenorrhea. RESULTS: Serum leptin levels were strongly related to body mass index (BMI) in each group, but there was no difference in the mean serum leptin levels among the BMI-matched study groups. A significant difference in the mean serum leptin levels was found between the non-obese and obese control groups (P<0.001) and between the non-obese and obese PCOS groups (P<0.001). CONCLUSIONS: These findings indicate that circulating leptin levels in women with normal menstrual cycles and those with ovarian dysfunction are strongly related to BMI. Leptin does not appear to be primarily involved in regulating ovarian function.     

Leptin and ovarian folliculogenesis: implications for ovulation induction and ART outcomes

Leptin participates in regulation of ovarian folliculogenesis indirectly via control of luteinizing hormone and follicle-stimulating hormone secretion. More recent evidence suggests that leptin also has direct regulatory actions on the developing follicle. The presence of leptin receptors on follicular cells, including oocytes, and early preimplantation embryos suggests that leptin may play a direct physiologic role in follicular maturation, oocyte development, and early cleavage. Because circulating leptin levels are directly related to body adiposity, elevated leptin concentrations associated with obesity may partly explain the negative impact of obesity on fertility. The influence of leptin on follicular development and oocyte maturation has important implications for ovulation induction and assisted reproductive technologies. Moreover, polycystic ovarian syndrome may be associated with altered leptin phsyiology.     

白细胞介素-1α对卵巢上皮细胞及卵巢癌细胞11β类固醇脱氢酶基因表达的影响

目的探讨白细胞介素1α(IL1α)对正常人卵巢上皮细胞及卵巢癌细胞株11β类固醇脱氢酶(11βHSD)基因表达的影响。方法体外培养人卵巢上皮细胞(HOSE)及卵巢癌细胞株SKOV3、PEO4和PEO14,应用逆转录多聚酶链反应(RTPCR)和实时荧光定量聚合酶链反应(realtimePCR)方法比较上述4种细胞中11β类固醇脱氢酶1(11βHSD1)、11β类固醇脱氢酶2(11βHSD2)和白细胞介素1受体(IL1R)mRNA水平的表达及加入不同浓度的IL1α后,4种细胞中11βHSD1和11βHSD2mRNA表达水平的变化。结果正常卵巢上皮细胞中11βHSD1和IL1RmRNA表达水平较高,11βHSD2mRNA表达水平较低;而卵巢癌细胞株SKOV3和PEO4中11βHSD1和IL1RmRNA表达水平较低,11βHSD2mRNA表达水平较高。加入不同浓度的IL1α后,正常卵巢上皮细胞11βHSD1mRNA表达水平明显升高(P<0.01);PEO14细胞11βHSD1mRNA表达水平也升高(P<0.05);SKOV3和PEO411βHSD1mRNA表达水平无明显变化;正常卵巢上皮细胞11βHSD2mRNA表达水平无明显变化,卵巢癌细胞株PEO4、SKOV3及PEO1411βHSD2mRNA表达水平不同程度升高(P<0.05)。结论卵巢癌细胞丧失了对炎性细胞因子白细胞介素1反应的能力;11β类固醇脱氢酶异构体表达形式的不同是肿瘤细胞转化的一种特征,它可能与卵巢上皮细胞的恶性转化有关。     

Monitoring gonadotropin-releasing hormone administration by measurement of urinary steroid conjugates

The use of measuring urinary steroid conjugates in nontimed, randomly collected morning urine samples expressed as a function of creatinine concentration was assessed to monitor ovarian response to pulsatile administration of gonadotropin-releasing hormone in ambulatory patients. This method of evaluating ovarian steroid production provided a convenient, inexpensive, and noninvasive means of monitoring responses to gonadotropin-releasing hormone treatments and documents that clomiphene-resistant amenorrheic patients can be induced to ovulate with appropriate gonadotropin-releasing hormone therapy. Different ovarian responses in the same woman to similar doses and frequencies of gonadotropin-releasing hormone indicate that discrete adjustments of individual doses may be required to facilitate consistent ovulatory responses. The strategy presented here allows for subsequent gonadotropin-releasing hormone therapy in the individual patient to be determined by an objective and quantifiable ovarian response to an initial treatment.