Modulation of appetite by gonadal steroid hormones

The Effect of the Menstrual Cycle on Energy Intake: A Systematic Review and Meta-analysis

CONTEXT

Energy intake may differ across the menstrual cycle, with some studies identifying greater energy intake in the luteal phase (LP) compared with the follicular phase (FP) and others finding no clear differences. To date, no study has systematically synthesized the available data to draw more definite conclusions while considering any methodological inconsistencies between studies.

OBJECTIVE

The aim was to conduct a systematic review/meta-analysis in an effort to determine if there are differences in energy intake between the FP and LP.

DATA SOURCES

A systematic search strategy was developed and the search was conducted in 5 databases for studies that investigated any changes in energy intake across menstrual phases.

DATA EXTRACTION

Using Covidence, studies were identified and included if they contained individuals between the ages of 18 and 45 years, maintained an average body mass index (BMI) of 18.5-25 kg/m2, had no history of disordered eating, and included energy intake and menstrual cycle measurements in the FP and LP.

DATA ANALYSIS

Effect sizes were calculated for each study and a random-effects model was used to pool the results of each study.

RESULTS

Fifteen datasets were included consisting of 330 female participants with a mean age of 26 ± 4 years and mean BMI of 22.4 ± 2.3 kg/m2. Overall, there was a statistically significant difference (standardized mean difference = 0.69; P = .039) with increased energy intake in the LP compared with the FP (crude 168 kcal⋅d-1 average difference between phases).

CONCLUSION

Energy intake was found to be greater in the LP compared with the FP, providing insight into the effect of the menstrual cycle on energy intake. However, there were repeated methodological inconsistencies and future work should strive to utilize best practices for both energy intake measurement and menstrual phase specification.

The role of ovarian hormone dynamics in metabolic phenotype and gene expression in female mice

Ovarian hormones, particularly estradiol, play an important role in the regulation of metabolic function including in food intake, thermogenesis, activity, fat distribution, and overall weight management. While it is known that weight and food intake follow cyclical patterns across the rodent estrous cycle, the majority of metabolic studies still focus on ovariectomized rodent models and estrogen replacement. Here we provide a comprehensive metabolic profiling of female mice under different ovarian hormone states, from having naturally-cycling ovarian hormone levels to complete ovarian hormone depletion and "estrous cycle-like" estrogen replacement (0.2 or 1 μg estradiol benzoate every 4 days). Every domain of metabolic function that we examined including activity levels, food intake, and body composition was affected by ovariectomy and contributed to >30 % weight gain and nearly two-fold increase in fat mass in ovarian hormone-depleted mice over the 12-week period. By combining physiological and hormone replacement paradigms, we show that cyclical estrogen levels are necessary and sufficient to maintain optimal body weight and fat mass. We show that the hypothalamic expression of genes encoding estrogen receptor alpha (Esr1) and neuropeptides involved in feeding behavior (Agrp, Pomc) changes across the cycle and with ovariectomy, and is partially "rescued" by cyclical estrogen treatment. The drastic fat mass changes following ovariectomy are accompanied by changes in adipose tissue gene expression, including a decreased responsiveness to estrogens due to Esr1 down-regulation. Our study highlights the importance of understanding the dynamic regulation of metabolic function by ovarian hormones and calls for more naturalistic and higher-resolution approaches to studying the molecular basis of ovarian hormone action.

Hormonal Contraceptive Use and Affective Disorders: An Updated Review

Hormonal contraceptives have given women historic freedoms and control over their fertility. At the same time, the potential side effects and unintended consequences of hormonal contraceptive use remain unclear due to a severe lack of funding and research. In this review, we summarize what is currently known about the impact of hormonal contraceptive use on mood symptoms, depression, and premenstrual disorders, and propose using the Social Signal Transduction Theory of Depression as a framework to generate predictions about the mechanistic pathways through which contraceptive use is associated with depression risk. The highest-quality evidence suggests that some types of contraceptives increase depression risk for some women. However, some contraceptives also appear to decrease depression risk in some instances. Key risk factors that predict depression following hormonal contraceptive use include age/age at onset of contraceptive use and mental health history/susceptibility. Hormonal contraceptives differ in ways that influence mood-related outcomes and can be used to treat depression in some women, especially those whose depression symptoms fluctuate across the cycle, indicating the potential presence of a premenstrual disorder. Looking forward, research, and funding for this research, is needed to elucidate the mechanistic pathways through which the use of different contraceptives impacts mood in different women to allow for a precision medicine approach to contraceptive treatment. In the meantime, health care providers should adopt patient-centered, "mindful prescribing" approaches to contraceptive counseling.

Intranasal Delivery of a Ghrelin Mimetic Engages the Brain Ghrelin Signaling System in Mice

Ghrelin, the endogenous ligand of the growth hormone secretagogue receptor (GHSR), promotes food intake and other feeding behaviors, and stimulates growth hormone (GH) release from the pituitary. Growth hormone secretagogues (GHS), such as GHRP-6 and MK-0677, are synthetic GHSR ligands that activate orexigenic neuropeptide Y neurons that coexpress agouti-related peptide (AgRP) in the arcuate nucleus of the hypothalamus when administered systemically. Systemic GHRP-6 also stimulates GH release in humans and rats. Thus, GHS and ghrelin have therapeutic relevance in patients who could benefit from its orexigenic and/or GH-releasing effects. This study examined whether intranasal delivery of ghrelin, GHRP-6, or MK-0677 engages the brain ghrelin signaling system. Effective compounds and doses were selected based on increased food intake after intranasal application in mice. Only GHRP-6 (5 mg/kg) increased food intake without adverse effects, prompting detailed analysis of meal patterns, neuronal activation in the arcuate nucleus (via Fos mapping) and neurochemical identification of c-fos messenger RNA (mRNA)-expressing neurons using RNAscope. We also assessed the effect of intranasal GHRP-6 on serum GH levels. Intranasal GHRP-6 increased food intake by increasing meal frequency and size. Fos expression in the arcuate nucleus was higher in GHRP-6-treated mice than in saline controls. When examining the neurochemical identity of c-fos-mRNA-expressing neurons, we found coexpression with 63.5 ± 1.9% Ghsr mRNA, 79 ± 6.8% Agrp mRNA, and 11.4 ± 2.5% Ghrh mRNA, demonstrating GHRP-6's ability to engage arcuate nucleus neurons involved in food intake and GH release. Additionally, intranasal GHRP-6 elevated GH serum levels. These findings suggest that intranasal GHRP-6, but not ghrelin or MK-0677, can engage the brain ghrelin signaling system.

Ovarian Stimulation Effects on Ghrelin Secretion and Reproductive Potential

OBJECTIVE

Finely regulated Ghrelin (Ghrl) secretion is essential during early pregnancy, as infra or supraphysiologic levels can be detrimental. Since oestrogens stimulate Ghrl synthesis, ovarian stimulation (OS) might increase ghrelinemia, thus being detrimental for fertility. The aim of this work was to evaluate whether OS increases ghrelinemia and associates with maternal endocrine and immune biomarkers and reproductive success.

DESIGN

The 97 women undergoing assisted reproduction were grouped as follows: OS: undergoing OS and fresh embryo transfer (n = 35); FET: undergoing frozen embryo transfer in a cycle different from that of OS (n = 25) and, OD: undergoing embryo transfer in oocyte donation cycles (n = 37). At embryo transfer day, several endocrine and immune biomarkers were assessed.

RESULTS

OS patients showed significantly higher serum estradiol, progesterone and Ghrl, than those not stimulated. Patients that suffered miscarriage showed significantly lower concentrations of sex-hormones, with a similar trend for Ghrl, that deserves further investigation. Moreover, OS patients showed decreased frequencies of circulating T cells and reduced ratios of uNK/NK cells, which significantly associated with serum levels of sex-hormones. Besides, ROC curves identified cut-off values predictive of clinical pregnancy and/or miscarriage for peripheral counts of uNK cells, T cells, and uNK/NK cells ratio.

CONCLUSIONS

As hypothesised, OS significantly increased serum Ghrl in correlation with sex-hormone levels. These last, significantly associated with maternal immune response and reproductive outcome. Although Ghrl exhibited a similar profile, it did not reach statistical significance, indicating the need for further investigation. Additionally, the identification of maternal immunological cut-off values holds significant clinical relevance.

Visceral fat distribution: Interracial studies

Visceral adipose tissue, a type of abdominal adipose tissue, is highly involved in lipolysis. Because increased visceral adiposity is strongly associated with the metabolic complications related with obesity, such as type 2 diabetes and cardiovascular disease, there is a need for precise, targeted, personalized and site-specific measures clinically. Existing studies showed that ectopic fat accumulation may be characterized differently among different populations due to complex genetic architecture and non-genetic or epigenetic components, ie, Asians have more and Africans have less visceral fat vs Europeans. In this review, we summarize the effects of multiple non-genetic and genetic factors on visceral fat distribution across races. Non-genetic factors include diet, socioeconomic status, sex hormones and psychological factors, etc. We examine genetic factors of racial differences in visceral fat content as well as possible regulatory pathways associated with interracial visceral fat distribution. A comprehensive understanding of both genetic and non-genetic factors that influence the distribution of visceral fat among races, leads us to predict risk of abdominal obesity and metabolic diseases in ethnic groups that enables targeted interventions through accurate diagnosis and treatment as well as reduced risk of obesity-associated complications.

The Effect of Multi-Strategy Nutrition Education Programs on Hedonic Hunger and Nutrition Status in Adolescents

Objective: Increasing the awareness of adolescents about hedonic hunger, understanding the difference between homeostatic hunger and hedonic hunger, and adolescents learning to control themselves to stop excessive food consumption are extremely important for a healthy adulthood. The study aimed to evaluate the effects of the multi-strategy nutrition education programs (MSNEP) on hedonic hunger, food addiction, nutrition literacy, and nutritional status in adolescents. Methods: This study was planned using a pre-test and post-test design. The MSNEP was conducted with 132 adolescents (11-15 years; 69 boys, 63 girls) for 4 weeks (45 min-1 h/session). Data were obtained using questionnaires with face-to-face interviews at pre-education (baseline) and post-education (week 4 and week 8). The survey form included sociodemographic information, nine item short version of Children's Power of Food Scale (C-PFS-9), the Yale Food Addiction Scale for Children 2.0 (YFAS-C 2.0), the Adolescent Nutrition Literacy Scale (ANLS), anthropometric measurements, and 24-hour dietary recall. Results: A decrease in C-PFS-9 total scores was found compared to the baseline (p < 0.001). While the YFAS-C 2.0 score decreased in boys compared to the baseline (p < 0.05), no significant difference was found in girls (p > 0.05). A difference was found in the ANLS scores for girls (p = 0.01), but no difference was found in the scores for boys during the study (p > 0.05). At week 4, the consumption of dairy products, legumes, vegetables and fruits, bread and grains, nuts, and hard-shelled seeds increased compared to the baseline (p < 0.05). Also, daily protein and fiber intake increased (p < 0.05). Accordingly, a higher YFAS-C 2.0 score predicted greater hedonic hunger. A lower ANLS score was a predictor for higher food taste and food available scores. Conclusions: In conclusion, the MSNEP was found to have positive effects on hedonic hunger, food addiction, nutritional literacy, and healthy eating behaviors. The study revealed differences between girls and boys. In order to maintain healthy body weights in adolescents, it is recommended that the MSNEP be provided in schools.

Sex-dimorphic functions of orexin in neuropsychiatric disorders

The orexin system regulates a variety of physiological functions, including the sleep-wake cycle, addiction, foraging behavior, stress and cognitive functioning. Orexin levels in central and peripheral are related to the pathogenesis of many diseases, most notably the narcolepsy, eating disorders, stress-related psychiatric disorders, and neurodegenerative diseases. Recently, it has been reported that the orexin system is distinctly sexually dimorphic, and is strongly associated with neuropsychiatric disorders. In this review, we analyzed advancements in the sex differences in the orexin system and their connection to psychoneurological conditions. Considering the scarcity of research in this domain, more research is imperative to reveal the underlying mechanisms.

A Review on in-vivo and in-vitro Models of Obesity and Obesity-Associated Co-Morbidities

BACKGROUND

Obesity is becoming a global pandemic with pandemic proportions. According to the WHO estimates, there were over 1.9 billion overweight individuals and over 650 million obese adults in the globe in 2016. In recent years, scientists have encountered difficulties in choosing acceptable animal models, leading to a multitude of contradicting aspects and incorrect outcomes. This review comprehensively evaluates different screening models of obesity and obesity-associated comorbidities to reveal the advantages and disadvantages/limitations of each model while also mentioning the time duration each model requires to induce obesity.

METHODOLOGY

For this review, the authors have gone through a vast number of article sources from different scientific databases, such as Google Scholar, Web of Science, Medline, and PubMed.

RESULTS

In-vivo models used to represent a variety of obesity-inducing processes, such as diet-induced, drug-induced, surgical, chemical, stress-induced, and genetic models, are discussed. Animal cell models are examined with an emphasis on their use in understanding the molecular causes of obesity, for which we discussed in depth the important cell lines, including 3T3-L1, OP9, 3T3-F442A, and C3H10T1/2. Screening models of obesity-associated co-morbidities like diabetes, asthma, cardiovascular disorders, cancer, and polycystic ovarian syndrome (PCOS) were discussed, which provided light on the complex interactions between obesity and numerous health problems.

CONCLUSION

Mimicking obesity in an animal model reflects multifactorial aspects is a matter of challenge. Future studies could address the ethical issues surrounding the use of animals in obesity research as well as investigate newly developed models, such as non-mammalian models. In conclusion, improving our knowledge and management of obesity and related health problems will require ongoing assessment and improvement of study models.

MicroRNA-21 modulates brown adipose tissue adipogenesis and thermogenesis in a mouse model of polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in premenopausal women, is associated with increased obesity, hyperandrogenism, and altered brown adipose tissue (BAT) thermogenesis. MicroRNAs play critical functions in brown adipocyte differentiation and maintenance. We aim to study the role of microRNA-21 (miR-21) in altered energy homeostasis and BAT thermogenesis in a PCOS mouse model of peripubertal androgen exposure.

METHODS

Three-week-old miR-21 knockout (miR21KO) or wild-type (WT) female mice were treated with dihydrotestosterone (DHT) or vehicle for 90 days. Body composition was determined by EchoMRI. Energy expenditure (EE), oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were measured by indirect calorimetry. Androgen receptor (AR), and markers of adipogenesis, de novo lipogenesis, angiogenesis, extracellular matrix remodeling, and thermogenesis were quantified by RT-qPCR and/or Western-blot.

RESULTS

MiR-21 ablation attenuated DHT-mediated increase in body weight while having no effect on fat or BAT mass. MiR-21 ablation attenuated DHT-mediated BAT AR upregulation. MiR-21 ablation did not alter EE; however, miR21KO DHT-treated mice have reduced VO2, VCO2, and RER. MiR-21 ablation reversed DHT-mediated decrease in food intake and increase in sleep time. MiR-21 ablation decreased some adipogenesis (Adipoq, Pparγ, and Cebpβ) and extracellular matrix remodeling (Mmp-9 and Timp-1) markers expression in DHT-treated mice. MiR-21 ablation abolished DHT-mediated increases in thermogenesis markers Cpt1a and Cpt1b, while decreasing CIDE-A expression.

CONCLUSIONS

Our findings suggest that BAT miR-21 may play a role in regulating DHT-mediated thermogenic dysfunction in PCOS. Modulation of BAT miR-21 levels could be a novel therapeutic approach for the treatment of PCOS-associated metabolic derangements.

Ovulatory cycle shifts in human motivational prioritisation of sex and food

Previous research on the endogenous effects of ovarian hormones on motivational states in women has focused on sexual motivation. The Motivational Priority Shifts Hypothesis has a broader scope. It predicts a shift from somatic to reproductive motivation when fertile. In a highly powered preregistered online diary study across 40 days, we tested whether 390 women report such an ovulatory shift in sexual and eating motivation and behaviour. We compared 209 naturally cycling women to 181 women taking hormonal contraceptives (HC) to rule out non-ovulatory changes across the cycle as confounders. We found robust ovulatory decreases in food intake and increases in general sexual desire, in-pair sexual desire and initiation of dyadic sexual behaviour. Extra-pair sexual desire increased mid-cycle, but the effect did not differ significantly in HC women, questioning an ovulatory effect. Descriptively, solitary sexual desire and behaviour, dyadic sexual behaviour, appetite, and satiety showed expected mid-cycle changes that were diminished in HC women, but these failed to reach our strict preregistered significance level. Our results provide insight into current theoretical debates about ovulatory cycle shifts while calling for future research to determine motivational mechanisms behind ovulatory changes in food intake and considering romantic partners' motivational states to explain the occurrence of dyadic sexual behaviour.

Longitudinal study of the impact of the COVID-19 pandemic on diet and physical activity among Latinos of Mexican ancestry

BACKGROUND

The COVID-19 pandemic caused societal disruption in the United States and most of the world, affecting many aspects of life, including healthcare and health-related behaviors such as diet, food security, and physical activity. Communities with economic and health disparities may have been particularly affected. This study was undertaken to determine how conditions in the early pandemic (January, 2021-February, 2022) affected Latino patients of Mexican Ancestry at high risk of type 2 diabetes mellitus who participated in El Banco por Salud biobank project in Tucson, Arizona.

METHODS

Baseline, prepandemic measurements were available in 17, 21, and 60 patients with normal hemoglobin A1c (HbA1c), prediabetes, and type 2 diabetes, respectively.

RESULTS

People with healthy HbA1c were significantly younger, less obese, and had higher HDL cholesterol. HbA1c was unaffected by the pandemic in any group. Triglycerides, total and HDL cholesterol levels fell in all groups during the pandemic. Physical activity levels in all groups were remarkably low, with most reporting no engagement in any voluntary physical activity. Engagement in physical activity or its enjoyment was lower in patients with diabetes and prediabetes than in younger, less obese patients. Major diet differences were between men and women and were present before the pandemic. Women consumed significantly more vegetables, fruit, and salad than men. The only pandemic-related change in diet was a drop in egg consumption, possibly explaining the fall in total cholesterol.

CONCLUSION

Societal disruption during the COVID-19 pandemic had minimal effects on adverse health-related behaviors, cardiometabolic risk, or changes in glycemic control in a Latino community with diabetes and healthcare disparities in the Southwest US.

Prolonged tamoxifen-enriched diet is associated with cardiomyopathy and nutritional frailty in mice

Tamoxifen (TAM) is required for gene recombination in the inducible Cre/lox system. The TAM-enriched diet is considered safe, with negligible impact on animal wellbeing. However, studies reporting the long-term effects of the TAM diet and its potential impact on experimental outcomes are scarce. We conducted a longitudinal study on mice exposed to a 4-week dietary TAM citrate supplementation. Several parameters were recorded, such as body weight, body composition, mortality, and cardiac function. The collagen1a2 (Col1a2) transgenic mouse was used to assess TAM-induced recombination in vivo in cardiac fibroblasts followed by myocardial infarction (MI). The impact of TAM on the MI outcome was also evaluated. The recombination efficiency and cytotoxic effect of the TAM active metabolite, 4-hydroxy-tamoxifen (4-OHT), were assessed in vitro. Mice exposed to a TAM diet showed body weight loss and a 10% increase in mortality (P = 0.045). The TAM diet decreased cardiac function and induced cardiac remodeling, indicated by decreased fractional shortening from 32.23% to 19.23% (P = 0.001) and left ventricular (LV) wall thinning. All measured parameters were reversed to normal when mice were returned to a normal diet. Infarcted Col1a2-CreER mice on the TAM regimen showed gene recombination in fibroblasts, but it was associated with a substantial increase in mortality post-surgery (2.5-fold) compared to the controls. In vitro, 4-OHT induced gene editing in fibroblasts; however, cell growth arrest and cytotoxicity were observed at high concentrations. In conclusion, prolonged exposure to the TAM diet can be detrimental and necessitates careful model selection and interpretation of the results.

The effects of dietary net energy on grow-finish performance and carcass characteristics of market gilts managed with immunological suppression of ovarian function and estrus (Improvest)

The objective was to determine the effects of net energy (NE) during the grow-finish period on live performance and carcass characteristics of market gilts managed with immunological suppression of ovarian function and estrus (Improvest®; IMP) compared with market gilts not managed with Improvest (CON). The 104-d study began when 1,008 gilts (11 wk old; average starting weight of 30.8 kg) were allocated by weight to 48 pens with 21 gilts/pen. Half of the pens were randomly selected to be managed with Improvest while the other half of the pens were not managed with Improvest. Three dietary programs differing in their NE were formulated over five dietary phases (according to standardized ileal digestible lysine requirements) to provide an average of 2,218 kcal/kg (low NE), 2,343 kcal/kg (medium NE), or 2,468 kcal/kg (high NE). The experiment was designed as a 2 × 3 factorial with main effects of Improvest management and NE. For the overall study period, there were no significant interactions (P ≥ 0.20) for average daily feed intake (ADFI), average daily gain (ADG), or Gain:Feed (G:F). There were also no significant interactions between Improvest management and NE (P ≥ 0.30) for carcass characteristics. However, IMP gilts consumed more feed (6.8% greater ADFI; P < 0.01), grew faster (5.0% greater ADG; P < 0.01), were less efficient (1.8% lower G:F; P < 0.01), heavier (3.5 kg hot carcass weight; P < 0.01), and fatter (1.9 mm greater backfat thickness and 1.26% less predicted lean carcass yield; P < 0.01). No difference (P = 0.21) in carcass dressing percentage between IMP and CON gilts was reported. For the overall study period, gilts fed low NE and medium NE diets consumed more feed compared with gilts fed high NE diets (6.8% more ADFI for low NE and 5.7% more for medium NE; P < 0.01), and gilts fed low NE diets grew 2.5% slower (P < 0.01) than gilts fed medium NE diets, while gilts fed high NE diets were intermediate and not different from the other NE treatments. This resulted in gilts fed Low NE diets being the least efficient (3.8% lower G:F than medium NE and 7.1% lower G:F than High NE; P < 0.01). Overall, these data indicate that typical Improvest response levels were sustained at each of the NE treatments evaluated in this study as there were no significant interactions for Improvest management and NE; however, consideration should still be provided to the known production impacts of low NE diets.

Neonatal inhibition of androgen activity alters the programming of body weight and orexinergic peptides differentially in male and female rats

The involvement of androgens in the regulation of energy metabolism has been demonstrated. The main objective of the present research was to study the involvement of androgens in both the programming of energy metabolism and the regulatory peptides associated with feeding. For this purpose, androgen receptors and the main metabolic pathways of testosterone were inhibited during the first five days of postnatal life in male and female Wistar rats. Pups received a daily s.c. injection from the day of birth, postnatal day (P) 1, to P5 of Flutamide (a competitive inhibitor of androgen receptors), Letrozole (an aromatase inhibitor), Finasteride (a 5-alpha-reductase inhibitor) or vehicle. Body weight, food intake and fat pads were measured. Moreover, hypothalamic Agouti-related peptide (AgRP), neuropeptide Y (NPY), orexin, and proopiomelanocortin (POMC) were analyzed by quantitative real-time polymerase chain reaction assay. The inhibition of androgenic activity during the first five days of life produced a significant decrease in body weight in females at P90 but did not affect this parameter in males. Moreover, the inhibition of aromatase decreased hypothalamic AgRP mRNA levels in males while the inhibition of 5α-reductase decreased hypothalamic AgRP and orexin mRNA levels in female rats. Finally, food intake and visceral fat, but not subcutaneous fat, were affected in both males and females depending on which testosterone metabolic pathway was inhibited. Our results highlight the differential involvement of androgens in the programming of energy metabolism as well as the AgRP and orexin systems during development in male and female rats.

Astrocytic Dagla Deletion Decreases Hedonic Feeding in Female Mice

Introduction: Endocannabinoids and exogenous cannabinoids are potent regulators of feeding behavior and energy metabolism. Stimulating cannabinoid receptor signaling enhances appetite, particularly for energy-dense palatable foods, and promotes energy storage. To elucidate the underlying cellular mechanisms, we investigate here the potential role of astrocytic endocannabinoid 2-arachidonoylglycerol (2-AG). Astrocytes provide metabolic support for neurons and contribute to feeding regulation but the effect of astrocytic 2-AG on feeding is unknown. Materials and Methods: We generated mice lacking the 2-AG synthesizing enzyme diacylglycerol lipase alpha (Dagla) in astrocytes (GLAST-Dagla KO) and investigated hedonic feeding behavior in male and female mice. Body weight and baseline water and food intake was characterized; additionally, the mice went through milk, saccharine, and sucrose preference tests in fed and fasted states. In female mice, the estrous cycle stages were identified and plasma levels of female sex hormones were measured. Results: We found that the effects of the inducible astrocytic Dagla deletion were sex-specific. Acute milk preference was decreased in female, but not in male mice and the effect was most evident in the estrus stage of the cycle. This prompted us to investigate sex hormone profiles, which were found to be altered in GLAST-Dagla KO females. Specifically, follicle-stimulating hormone was elevated in the estrus stage, luteinizing hormone in the proestrus, and progesterone was increased in both proestrus and estrus stages of the cycle compared with controls. Conclusions: Astrocytic Dagla regulates acute hedonic appetite for palatable food in females and not in males, possibly owing to a deregulated female sex hormone profile. It is plausible that endocannabinoid production by astrocytes at least partly contributes to the greater susceptibility to overeating in females. This finding may also be important for understanding the effects of exogenous cannabinoids on sex hormone profiles.

Obesity: a gender-view

PURPOSE

There is a growing awareness of the importance of understanding gender differences in obesity. The aim of this short review was to revise the current evidence on anthropometric characteristics and nutritional and pharmacological aspects of obesity from a gender perspective.

METHODS

A literature search within PubMed was performed. Selected publications related to obesity and gender differences were reviewed.

RESULTS

The prevalence of obesity among men is higher than in women, but women have a higher percentage of body fat content compared to men, and gender appears to be an important factor in the manifestation of central (android) or peripheral (gynoid) obesity. In addition, while in most clinical trials, women are still underrepresented, in clinical registration trials of anti-obesity drugs, women are commonly up-represented and gender-specific analysis is uncommon. Considering that adipose tissue is one of the factors affecting the volume of distribution of many drugs, mainly lipophilic drugs, gender differences might be expected in the pharmacokinetics and pharmacodynamics of anti-obesity drugs. Indeed, although Liraglutide 3 mg, a long-acting glucagon-like peptide-1 receptor agonist, and naltrexone/bupropion display lipophilic properties, currently, a gender-dose adjustment for both these drugs administration is not recommended. In addition, despite that predicted responders to treatment offer substantial opportunities for efficient use, especially of expensive new therapies, such as anti-obesity drugs, data on gender differences to identify early responders to both these have not yet been investigated. Finally, bariatric surgery gender disparity reflects healthcare practices. Weight loss similar, but differing effects: women need more correction and face psychology challenges; men have worse physiology and fewer comorbidity improvements.

CONCLUSION

Gender differences exist in obesity prevalence and phenotype, body fat distribution, drug efficacy, clinical trial representation, and different secondary effects of bariatric surgery. Gender is an important variable in obesity analysis.

Fasting diets: what are the impacts on eating behaviors, sleep, mood, and well-being?

Fasting diets (FDs) have drawn great attention concerning their contribution to health and disease over the last decade. Despite considerable interest in FDs, the effect of fasting diets on eating behaviors, sleep, and mood-essential components of diet satisfaction and mental health- has not been addressed comprehensively. Understanding the critical role that fasting plays in these elements will open up potential treatment avenues that have not yet been explored. The aim of the present paper was to conduct a comprehensive critical review exploring the effects of fasting on eating behaviors, sleep, and mood. There is currently a lack of clarity regarding which fasting option yields the most advantageous effects, and there is also a scarcity of consistent trials that assess the effects of FDs in a comparable manner. Similarly, the effects and/or treatment options for utilizing FDs to modify eating and sleep behaviors and enhance mood are still poorly understood. Further researches aiming at understanding the impacts of various fasting regimes, providing new insights into the gut-brain axis and offering new treatment avenues for those with resistant anxiety and depression, are warranted. Alteration of eating behaviors can have lasting effects on various physiological parameters. The use of fasting cures can underpin ancient knowledge with scientific evidence to form a new approach to the prevention and treatment of problems associated with co-morbidities or challenges pertaining to eating behaviors. Therefore, a thorough examination of the various fasting regimens and how they impact disease patterns is also warranted.

Risk assessment of transgender people: implementation of a demasculinizing-feminizing rodent model including the evaluation of thyroid homeostasis

BACKGROUND

Individuals whose gender identity differs from the biological sex and the social norms are defined as transgender. Sometimes transgender undergo gender affirming hormone therapy, which lasts for the entire life making essential to evaluate its potential long-term effects. Moreover, transgender can represent a susceptible sub-group of population and specific attention is needed in risk assessment, including the development of targeted animal models. Aim of the study is the implementation of a rodent demasculinizing-feminizing model through the setting of appropriate dose of hormone therapy and the selection of specific biomarkers to evaluate the sex transition. Specific attention is paid to thyroid homeostasis due to the close link with reproductive functions. Four male adult rats/group were subcutaneously exposed to three doses plus control of β-estradiol valerate plus cyproterone acetate at: 0.045 + 0.2 (low), 0.09 + 0.2 (medium) and 0.18 + 0.2 (high) mg/dose, five times/week. The doses were selected considering the most recent recommendations for transgender woman. Sperm count, histopathological analysis (testis, liver, thyroid), testosterone, estradiol, triiodothyronine and thyroid-stimulating hormone serum levels and gene expression of sex dimorphic CYP450 were evaluated.

RESULTS

The doses induced feminizing-demasculinizing effects: decreased testosterone serum levels at the corresponding cisgender, increased estradiol, impairment of male reproductive function and reversal of sex-specific CYP liver expression. However, the medium and high doses induced marked liver toxicity and the low dose is considered the best choice, also for long-term studies in risk assessment. The alterations of thyroid indicated follicular cell hypertrophy supported by increased thyroid-stimulating hormone serum levels at the higher doses.

CONCLUSIONS

The implementation of animal models that mimic the effects of gender affirming hormone therapy is essential for supporting clinical studies in transgender people and filling data gap in order to ensure an appropriate risk assessment and a more accurate, personalized care for transgender people.

From gut microbiota to brain: implications on binge eating disorders

The prevalence of eating disorders has been increasing over the last 50 years. Binge eating disorder (BED) and bulimia nervosa (BN) are two typical disabling, costly and life-threatening eating disorders that substantially compromise the physical well-being of individuals while undermining their psychological functioning. The distressing and recurrent episodes of binge eating are commonly observed in both BED and BN; however, they diverge as BN often involves the adoption of inappropriate compensatory behaviors aimed at averting weight gain. Normal eating behavior is coordinated by a well-regulated trade-off between intestinal and central ingestive mechanism. Conversely, despite the fact that the etiology of BED and BN remains incompletely resolved, emerging evidence corroborates the notion that dysbiosis of gastrointestinal microbiome and its metabolites, alteration of gut-brain axis, as well as malfunctioning central circuitry regulating motivation, execution and reward all contribute to the pathology of binge eating. In this review, we aim to outline the current state of knowledge pertaining to the potential mechanisms through which each component of the gut-brain axis participates in binge eating behaviors, and provide insight for the development of microbiome-based therapeutic interventions that hold promise in ameliorating patients afflicted with binge eating disorders.

Cardiovascular health and the menopause, metabolic health

Estrogen depletion following menopause predisposes to increased risk of cardiovascular disease (CVD), mainly due to ischemic heart disease. This is mostly evident in cases with premature menopause. The pathophysiological basis for this atherosclerotic process is the accumulation of several risk factors, such as abdominal obesity, atherogenic dyslipidemia, insulin resistance and arterial hypertension. The presence of vasomotor symptoms may further augment this risk, especially in women younger than 60 years. Menopausal hormone therapy (MHT) exerts many beneficial effects on lipid profile and glucose homeostasis as well as direct arterial effects, and may reduce CVD risk if initiated promptly (i.e.,<60 years or within ten years of the final menstrual period). Transdermal estradiol and micronized progesterone or dydrogesterone are the safest regimens in terms of venous thromboembolic events (VTE) and breast cancer risk. In any case, an individualized approach, taking into account the patient's total CVD, VTE and breast cancer risk, is recommended.

The transplantation of the gut microbiome of fat-1 mice protects against colonic mucus layer disruption and endoplasmic reticulum stress induced by high fat diet

High-fat diets alter gut barrier integrity, leading to endotoxemia by impacting epithelial functions and inducing endoplasmic reticulum (ER) stress in intestinal secretory goblet cells. Indeed, ER stress, which is an important contributor to many chronic diseases such as obesity and obesity-related disorders, leads to altered synthesis and secretion of mucins that form the protective mucus barrier. In the present study, we investigated the relative contribution of omega-3 polyunsaturated fatty acid (PUFAs)-modified microbiota to alleviating alterations in intestinal mucus layer thickness and preserving gut barrier integrity. Male fat-1 transgenic mice (exhibiting endogenous omega-3 PUFAs tissue enrichment) and wild-type (WT) littermates were fed either an obesogenic high-fat diet (HFD) or a control diet. Unlike WT mice, HFD-fed fat-1 mice were protected against mucus layer alterations as well as an ER stress-mediated decrease in mucin expression. Moreover, cecal microbiota transferred from fat-1 to WT mice prevented changes in the colonic mucus layer mainly through colonic ER stress downregulation. These findings highlight a novel feature of the preventive effects of omega-3 fatty acids against intestinal permeability in obesity-related conditions.

TRPV1 enhances cholecystokinin signaling in primary vagal afferent neurons and mediates the central effects on spontaneous glutamate release in the NTS

The gut peptide cholecystokinin (CCK) is released during feeding and promotes satiation by increasing excitation of vagal afferent neurons that innervate the upper gastrointestinal tract. Vagal afferent neurons express CCK1 receptors (CCK1Rs) in the periphery and at central terminals in the nucleus of the solitary tract (NTS). While the effects of CCK have been studied for decades, CCK receptor signaling and coupling to membrane ion channels are not entirely understood. Previous findings have implicated L-type voltage-gated calcium channels as well as transient receptor potential (TRP) channels in mediating the effects of CCK, but the lack of selective pharmacology has made determining the contributions of these putative mediators difficult. The nonselective ion channel transient receptor potential vanilloid subtype 1 (TRPV1) is expressed throughout vagal afferent neurons and controls many forms of signaling, including spontaneous glutamate release onto NTS neurons. Here we tested the hypothesis that CCK1Rs couple directly to TRPV1 to mediate vagal signaling using fluorescent calcium imaging and brainstem electrophysiology. We found that CCK signaling at high concentrations (low-affinity binding) was potentiated in TRPV1-containing afferents and that TRPV1 itself mediated the enhanced CCK1R signaling. While competitive antagonism of TRPV1 failed to alter CCK1R signaling, TRPV1 pore blockade or genetic deletion (TRPV1 KO) significantly reduced the CCK response in cultured vagal afferents and eliminated its ability to increase spontaneous glutamate release in the NTS. Together, these results establish that TRPV1 mediates the low-affinity effects of CCK on vagal afferent activation and control of synaptic transmission in the brainstem.NEW & NOTEWORTHY Cholecystokinin (CCK) signaling via the vagus nerve reduces food intake and produces satiation, yet the signaling cascades mediating these effects remain unknown. Here we report that the capsaicin receptor transient receptor potential vanilloid subtype 1 (TRPV1) potentiates CCK signaling in the vagus and mediates the ability of CCK to control excitatory synaptic transmission in the nucleus of the solitary tract. These results may prove useful in the future development of CCK/TRPV1-based therapeutic interventions.

Association of eating behavior with symptoms of pelvic floor disorders in middle-aged women: An observational study

BACKGROUND

Estrogen deficiency during menopause, aging, reproductive history, and factors increasing intra-abdominal pressure may lead to structural and functional failure in the pelvic floor. Lifestyle choices, such as eating behavior, may contribute to pelvic floor disorders.

OBJECTIVES

The objective of the study was to investigate associations of eating behavior with symptoms of pelvic floor disorders, that is, stress urinary incontinence, urgency urinary incontinence, fecal incontinence, and constipation or defecation difficulties among middle-aged women.

DESIGN

A cross-sectional, observational study was performed using a population sample of 1098 Finnish women aged 47-55 years.

METHODS

Eating behavior, food consumption frequency, demographical, gynecological, and physical activity variables were assessed using self-report questionnaires. Logistic regression models were used to assess the associations of eating behavior, food frequency, and symptoms of pelvic floor disorders. Models were adjusted with demographical, gynecological, and physical activity variables.

RESULTS

In adjusted models, middle-aged women with disordered eating style were more likely to experience the symptoms of stress urinary incontinence (odds ratio (OR) 1.5, p = 0.002), and constipation or defecation difficulties (OR 1.4, p = 0.041). Adding body mass index into the models abolished associations. Of the studied food items, more frequent consumption of ready-made, highly processed foods (OR 1.5, p = 0.001), and fast foods (OR 1.5, p = 0.005) were independently associated with symptoms of stress urinary incontinence regardless of eating style, whereas consuming ready-made foods (OR 1.4, p = 0.048) was associated with symptoms of urgency urinary incontinence. Daily consumption of fruits (OR 0.8, p = 0.034) was independently associated with symptoms of stress urinary incontinence. Furthermore, we observed that daily consumption of porridge was associated with symptoms of constipation or defecation difficulties (OR 1.7, p = 0.010) independently of eating style. Alcohol consumption (OR 0.9, p = 0.015) was inversely associated with constipation and defecation difficulties. Women with overall higher quality diet had lower odds for stress urinary incontinence (OR 0.9, p = 0.002).

CONCLUSION

This study provides proof-of-concept evidence to the hypothesis that eating behavior and consuming certain food items are associated with perceived pelvic floor disorders. As a preventive action, eating behavior of women with the risk of these symptoms should be assessed, and guidance toward healthy eating patterns should be provided.

Delayed estrogen actions diminish food consumption without changing food approach, motor activity, or hypothalamic activation elicited by corticostriatal µ-opioid signaling

Mu-opioid receptor (μ-OR) signaling in forebrain sites including nucleus accumbens (Acb) and ventromedial prefrontal cortex (vmPFC) modulates reward-driven feeding and may play a role in the pathophysiology of disordered eating. In preclinical models, intra-Acb or intra-vmPFC μ-OR stimulation causes overeating and vigorous responding for food rewards. These effects have been studied mainly in male animals, despite demonstrated sex differences and estrogen modulation of central reward systems. Hence, the present study investigated sex differences and estrogen modulation of intra-Acb and intra-vmPFC μ-OR-driven feeding behaviors. First, the dose-related effects of intra-Acb and intra-vmPFC infusions of the μ-OR-selective agonist, DAMGO, were compared among intact female, ovariectomized (OVX) female, and intact male rats. The DAMGO feeding dose-effect function was flattened in intact females relative to the robust, dose-dependent effects observed in OVX females and intact males. Thus, in intact females, intra-Acb DAMGO failed to elevate food intake relative to vehicle, while intra-vmPFC DAMGO elevated food intake, but to a smaller degree compared to males and OVX females. Next, to explore the possible role of estrogen in mediating the diminished DAMGO response observed in intact females, OVX rats were given intra-Acb or intra-vmPFC infusions of DAMGO either immediately after a subcutaneous injection of 17-beta-estradiol 3-benzoate (EB; 5 μg/0.1 mL) or 24 h after EB injection. Intra-Acb DAMGO effects were not changed at the immediate post-EB time point. At the delayed post-EB timepoint, significant lordosis was noted and the duration of intra-Acb DAMGO-driven feeding bouts was significantly reduced, with no change in the number of bouts initiated, locomotor hyperactivity, or Fos immunoreactivity in hypothalamic feeding and arousal systems. Similarly, EB failed to alter the motor-activational effects of intra-vmPFC DAMGO while reducing feeding. These findings indicate that delayed, presumably genomically mediated estrogen actions modulate the μ-OR-generated motivational state by reducing consummatory activity while sparing goal-approach and general arousal/activity. The results additionally suggest that EB regulation of consummatory activity occurs outside of forebrain-μ-OR control of hypothalamic systems.

Feeding neurons integrate metabolic and reproductive states in mice

Balance between metabolic and reproductive processes is important for survival, particularly in mammals that gestate their young. How the nervous system coordinates this balance is an active area of study. Herein, we demonstrate that somatostatin (SST) neurons of the tuberal hypothalamus alter feeding in a manner sensitive to metabolic and reproductive states in mice. Whereas chemogenetic activation of SST neurons increased food intake across sexes, ablation decreased food intake only in female mice during proestrus. This ablation effect was only apparent in animals with low body mass. Fat transplantation and bioinformatics analysis of SST neuronal transcriptomes revealed white adipose as a key modulator of these effects. These studies indicate that SST hypothalamic neurons integrate metabolic and reproductive cues by responding to varying levels of circulating estrogens to modulate feeding differentially based on energy stores. Thus, gonadal steroid modulation of neuronal circuits can be context dependent and gated by metabolic status.

High estradiol levels during a long agonist IVF protocol are associated with decreased food intake, higher leptin concentrations, and lower levels of high-sensitivity C-reactive protein

PURPOSE

To study whether different hormonal phases affect appetite regulation, food intake, and concentrations of leptin, glucagon-like peptide-1 (GLP-1), and high-sensitivity C-reactive protein (hs-CRP) during a long agonist in vitro fertilization (IVF) protocol.

METHODS

Fifty-four infertile women were encountered thrice, the first of which was at the beginning of their period (low estradiol). The other two visits were during a gonadotrophin-releasing hormone (GnRH) analog downregulation (low estradiol) and at the end of a follicle-stimulating hormone (FSH) stimulation (high estradiol). The first visit was the reference; the women served as their controls. The concentrations of leptin, GLP-1, and hs-CRP were assessed from plasma. Dietary intake was assessed using food records (FRs). In addition, weight, height, body mass index (BMI), and plasma levels of estradiol, glucose, HbA1c, insulin, and lipids were monitored. Twenty-six of the subjects also had a postprandial test.

RESULTS

During the stimulation protocol, leptin concentrations elevated (P < 0.001), and energy intake decreased (P = 0.03), while estradiol levels increased (P < 0.001). GLP-1 levels unchanged (P = 0.75) and hs-CRP (P = 0.03) concentrations diminished, while estradiol levels increased.

CONCLUSION

No increased food intake or weight gain occurred during the stimulation protocol; thus, leptin may protect from overeating during high estradiol levels, and leptin resistance may not occur during a short follow-up. Also, a favorable anti-inflammatory effect was detected. During this study, we observed no harmful metabolic effects, which might affect negatively maternal health.

The influence of estrogen response element ERα signaling in the control of feeding behaviors in male and female mice

Circulating 17β-estradiol (E2) controls energy homeostasis and feeding behaviors primarily by its nuclear receptor, estrogen receptor (ER) α. As such, it is important to understand the role of ERα signaling in the neuroendocrine control of feeding. Our previous data indicated that the loss of ERα signaling through estrogen response elements (ERE) alters food intake in a female mouse model. Hence, we hypothesize that ERE-dependent ERα is necessary for typical feeding behaviors in mice. To test this hypothesis, we examined feeding behaviors on low-fat diet (LFD) and high-fat diet (HFD) in three mouse strains: total ERα knockout (KO), ERα knockin/knockout (KIKO), which lack a functional DNA-binding domain, and their wild type (WT) C57 littermates comparing intact males and females and ovariectomized females with or without E2 replacement. All feeding behaviors were recorded using the Biological Data Acquisition monitoring system (Research Diets). In intact male mice, KO and KIKO consumed less than WT mice on LFD and HFD, while in intact female mice, KIKO consumed less than WT and KO. These differences were primarily driven by shorter meal duration in the KO and KIKO. In ovariectomized females, E2-treated WT and KIKO consumed more LFD than KO driven in part by an increase in meal frequency and a decrease in meal size. On HFD, WT consumed more than KO with E2, again due to effects on meal size and frequency. Collectively, these suggest that both ERE-dependent and -independent ERα signaling are involved in feeding behaviors in female mice depending on the diet consumed.

The organizational role of ovarian hormones during puberty on risk for binge-like eating in rats

Puberty is a high-risk period for the development of dysregulated eating, including binge eating. While risk for binge eating in animals and humans increases in both males and females during puberty, the increased prevalence is significantly greater in females. Emerging data suggest that the organizational effects of gonadal hormones may contribute to the female preponderance of binge eating. In this narrative review, we discuss studies conducted in animals that have examined these organizational effects as well as the neural systems that may serve as intermediary mechanisms. Relatively few studies have been conducted, but data thus far suggest that pubertal estrogens may organize risk for binge eating, potentially by altering key circuits in brain reward pathways. These promising results highlight the need for future studies to directly test organizational effects of pubertal hormones using hormone replacement techniques and circuit-level manipulations that can identify pathways contributing to binge eating across development.

Neurodevelopmental Model Explaining Associations between Sex Hormones, Personality, and Eating Pathology

Clinical scientists have been investigating the relationships between sex hormones, personality, and eating disorders for decades. However, there is a lack of direct research that addresses whether personality mediates or moderates the relationships between sex hormones and eating pathology. Moreover, the neural mechanisms that underlie the interactive associations between these variables remain unclear. This review aims to summarize the associations between these constructs, describe a neural mechanism mediating these relationships, and offer clinical strategies for the early identification and intervention of eating disorders. The gathered evidence shows that aggressiveness, impulsivity, and obsessive-compulsiveness may mediate or moderate the relationships between sex hormones and eating pathology, but only among females. Furthermore, sex hormone receptor density in the mesocorticolimbic dopamine pathway may explain the neural mechanism of these associations. Future research should use more comprehensive personality measurements and assess the mediation and moderation effects of temperament while taking the hormone levels of women across menstrual cycles into account. Additionally, electroencephalography and functional magnetic resonance imaging should be implemented to directly assess brain activity and corroborate these findings.

The role of glucagon-like peptide-1 (GLP-1) in fluid and food intakes in vasopressin-deficient Brattleboro rats

Eating and drinking co-occur and many of the same mechanisms that control one are involved in the control of the other, making it difficult to isolate specific mechanisms for the control of fluid intake. Glucagon-like peptide-1 (GLP-1) is a peptide that seems to be involved in the endogenous control of both ingestive behaviors, but we lack a thorough understanding of how and where GLP-1 is acting to control fluid intake. Vasopressin-deficient Brattleboro rats are a model of hereditary hypothalamic diabetes insipidus that have been used extensively for the study of vasopressin actions in behavior and physiology. Here, we propose that these rats, that eat normally but drink excessively, provide a useful model to dissociate central controls of food and fluid intakes. As an initial step toward establishing this model for these purposes, we focused on GLP-1. Similar to the effect observed after treatment with a GLP-1 receptor (GLP-1R) agonist, the intake difference between wildtype and Brattleboro rats was largely a function in the number of licking bursts, indicating differences in post-ingestive feedback (e.g., satiation). When given central injections of a GLP-1R agonist, the effect on feeding was comparable between wildtype and Brattleboro rats, but the effect of drug on fluid intake was markedly exaggerated in Brattleboro rats. Additionally, Brattleboro rats did not respond to GLP-1R antagonism, whereas wildtype rats did. Taken together, these results suggest that Brattleboro rats exhibit a selective disruption to GLP-1's control of water intake. Overall, these experiments provide foundational studies of the ingestive behavior of Brattleboro rats and demonstrate the potential to use these rats to disentangle the effects of GLP-1 on food and fluid intakes.

The hypothalamic neuropeptide, QRFP, regulates high fat diet intake in female Long-Evans rats following ovariectomy

Obesity rates in women continue to increase throughout the lifespan and obesity-related comorbidities are prevalent in women in estrogen deficiency. The hypothalamic neuropeptide, QRFP, is an orexigenic peptide that increases the intake of high fat diet (HFD) in female rats and is overexpressed following ovariectomy (OVX). Therefore, the goal of the current series of experiments was to elucidate the effect of QRFP on HFD intake following OVX and determine if QRFP-26 administration in ovariectomized females altered expression of prepro-neuropeptide Y (NPY), agouti-related peptide (AgRP) and proopiomelanocortin (POMC) mRNA in the mediobasal hypothalamus (MBH) and prepro-orexin in the lateral hypothalamus (LH). The intake of HFD was measured following acute administration of QRFP-26 prior to or following estradiol benzoate (EB) treatment in ovariectomized females. When administered prior to EB treatment, QRFP-26 increased HFD intake. EB treatment attenuated the effects of QRFP-26 on HFD intake. Sub-chronic, continuous administration of QRFP-26 increased HFD intake and weight gain following OVX. Subchronic, continuous administration of QRFP siRNA into the 3rd ventricle via osmotic pump decreased prepro-QRFP mRNA levels in the MBH by ∼75%, decreased HFD intake and decreased weight gain following OVX. QRFP-26administration did not alter the expression of prepro-NPY, AgRP or POMC mRNA in the MBH, but decreased prepro-orexin mRNA in the LH of ovariectomized females. Overall, results from these studies support the orexigenic neuropeptide, QRFP, as an important mediator of the ingestion of highly palatable foods and subsequent weight gain in females during estrogen deficiency.

Sex and timing of gonadectomy relative to puberty interact to influence weight, body composition, and feeding behaviors in mice

Gonadal sex steroids are important regulators of energy balance in adult rodents, and gonadectomy (GDX) has opposing effects on weight gain in sexually mature males and females. Puberty is associated with the emergence of sex differences in weight, body composition, and feeding behaviors, yet the role of gonadal hormones at puberty remains unclear. To address this, we performed GDX or sham surgery in male and female C57Bl/6 mice at postnatal day (P)25 (prepubertal) or P60 (postpubertal) timepoints and measured weight and body composition for 35 days, after which ad libitum and operant food intake was measured using Feeding Experimentation Device 3 (FED3s) in the home cage. Consistent with previous studies, postpubertal GDX caused weight gain in females and weight loss in males and increased adiposity in both sexes. However, prepubertal GDX decreased weight gain and altered body composition across the adolescent transition (P25 to P60) in males but had no effect in females. Despite the varied effects on weight, GDX decreased food intake and motivation for food as assessed in operant tasks regardless of sex or timing of surgery relative to puberty. Our findings indicate that GDX interacts with both sex and age at surgery to influence weight, body composition, and feeding behavior.

CPT1A in AgRP neurons is required for sex-dependent regulation of feeding and thirst

BACKGROUND

Fatty acid metabolism in the hypothalamus has an important role in food intake, but its specific role in AgRP neurons is poorly understood. Here, we examined whether carnitinea palmitoyltransferase 1A (CPT1A), a key enzyme in mitochondrial fatty acid oxidation, affects energy balance.

METHODS

To obtain Cpt1aKO mice and their control littermates, Cpt1a(flox/flox) mice were crossed with tamoxifen-inducible AgRPCreERT2 mice. Food intake and body weight were analyzed weekly in both males and females. At 12 weeks of age, metabolic flexibility was determined by ghrelin-induced food intake and fasting-refeeding satiety tests. Energy expenditure was analyzed by calorimetric system and thermogenic activity of brown adipose tissue. To study fluid balance the analysis of urine and water intake volumes; osmolality of urine and plasma; as well as serum levels of angiotensin and components of RAAS (renin-angiotensin-aldosterone system) were measured. At the central level, changes in AgRP neurons were determined by: (1) analyzing specific AgRP gene expression in RiboTag-Cpt1aKO mice obtained by crossing Cpt1aKO mice with RiboTag mice; (2) measuring presynaptic terminal formation in the AgRP neurons with the injection of the AAV1-EF1a-DIO-synaptophysin-GFP in the arcuate nucleus of the hypothalamus; (3) analyzing AgRP neuronal viability and spine formations by the injection AAV9-EF1a-DIO-mCherry in the arcuate nucleus of the hypothalamus; (4) analyzing in situ the specific AgRP mitochondria in the ZsGreen-Cpt1aKO obtained by breeding ZsGreen mice with Cpt1aKO mice. Two-way ANOVA analyses were performed to determine the contributions of the effect of lack of CPT1A in AgRP neurons in the sex.

RESULTS

Changes in food intake were just seen in male Cpt1aKO mice while only female Cpt1aKO mice increased energy expenditure. The lack of Cpt1a in the AgRP neurons enhanced brown adipose tissue activity, mainly in females, and induced a substantial reduction in fat deposits and body weight. Strikingly, both male and female Cpt1aKO mice showed polydipsia and polyuria, with more reduced serum vasopressin levels in females and without osmolality alterations, indicating a direct involvement of Cpt1a in AgRP neurons in fluid balance. AgRP neurons from Cpt1aKO mice showed a sex-dependent gene expression pattern, reduced mitochondria and decreased presynaptic innervation to the paraventricular nucleus, without neuronal viability alterations.

CONCLUSIONS

Our results highlight that fatty acid metabolism and CPT1A in AgRP neurons show marked sex differences and play a relevant role in the neuronal processes necessary for the maintenance of whole-body fluid and energy balance.

Estradiol-mediated protection against high-fat diet induced anxiety and obesity is associated with changes in the gut microbiota in female mice

Decreased estrogens during menopause are associated with increased risk of anxiety, depression, type 2 diabetes and obesity. Similarly, depleting estrogens in rodents by ovariectomy, combined with a high-fat diet (HFD), increases anxiety and adiposity. How estrogens and diet interact to affect anxiety and metabolism is poorly understood. Mounting evidence indicates that gut microbiota influence anxiety and metabolism. Here, we investigated the effects of estradiol (E) and HFD on anxiety, metabolism, and their correlation with changes in gut microbiota in female mice. Adult C57BL/6J mice were ovariectomized, implanted with E or vehicle-containing capsules and fed a standard diet or HFD. Anxiety-like behavior was assessed and neuronal activation was measured by c-fos immunoreactivity throughout the brain using iDISCO. HFD increased anxiety-like behavior, while E reduced this HFD-dependent anxiogenic effect. Interestingly, E decreased neuronal activation in brain regions involved in anxiety and metabolism. E treatment also altered gut microbes, a subset of which were associated with anxiety-like behavior. These findings provide insight into gut microbiota-based therapies for anxiety and metabolic disorders associated with declining estrogens in menopausal women.

Mammalian models of diabetes mellitus, with a focus on type 2 diabetes mellitus

Although no single animal model replicates all aspects of diabetes mellitus in humans, animal models are essential for the study of energy balance and metabolism control as well as to investigate the reasons for their imbalance that could eventually lead to overt metabolic diseases such as type 2 diabetes mellitus. The most frequently used animal models in diabetes mellitus research are small rodents that harbour spontaneous genetic mutations or that can be manipulated genetically or by other means to influence their nutrient metabolism and nutrient handling. Non-rodent species, including pigs, cats and dogs, are also useful models in diabetes mellitus research. This Review will outline the advantages and disadvantages of selected animal models of diabetes mellitus to build a basis for their most appropriate use in biomedical research.

Transient effects of junk food on NAc core MSN excitability and glutamatergic transmission in obesity-prone female rats

OBJECTIVE

The nucleus accumbens (NAc) plays critical roles in eating and food seeking in rodents and humans. Diets high in fats and sugars ("junk food") produce persistent increases in NAc function in male obesity-prone rats. This study examines effects of junk food and junk food deprivation on NAc core medium spiny neuron (MSN) excitability and glutamate transmission in females.

METHODS

Obesity-prone female rats were given access to ad libitum junk food for 10 days, and recordings were made from MSNs in the NAc core immediately or after a short (27-72 hours) or long (14-16 days) junk food deprivation period in which rats were returned to ad libitum standard chow. Controls remained on chow throughout. Whole-cell slice electrophysiology was used to examine MSN intrinsic membrane and firing properties and glutamatergic transmission.

RESULTS

The study found that intrinsic excitability was reduced, whereas glutamatergic transmission was enhanced, after the short, but not long, junk food deprivation period. A brief junk food deprivation period was necessary for increases in NAc calcium-permeable-AMPA receptor transmission and spontaneous excitatory postsynaptic current (sEPSC) frequency, but not for increases in sEPSC amplitude.

CONCLUSIONS

This study reveals that females are protected from long-lasting effects of sugary fatty foods on MSN neuronal function and provides evidence for sex-specific effects on plasticity in brain centers that influence food-seeking and feeding behavior.

Energy balance in cancer survivors at risk of weight gain: a review

PURPOSE

The study of energy balance [i.e., energy intake (EI) and energy expenditure (EE)] is a powerful tool for understanding body weight regulation and may contribute to our understanding of rapid weight gain risk in certain cancer survivors post-diagnosis. The purpose of this review was to summarize studies that assessed longitudinal, prospective changes in components of energy balance from diagnosis/start of treatment to any duration of follow-up in cancer survivors with prior evidence of weight gain (breast, prostate, thyroid, gynecologic, testicular, and acute lymphoblastic leukemia) RESULTS: The available literature suggests that energy balance components may be altered in cancer survivors who have a heightened risk of weight gain post-diagnosis. The evidence for EI was overall inconsistent. Conversely, decreases in resting and physical activity EE during the active phases of treatment (e.g., chemotherapy, hypothyroid state) were commonly noted, which then slowly rebounded towards baseline levels at the end of treatment and during follow-up assessments. Much of this evidence is based on data collected from breast cancer survivors, which highlights a paucity of data currently available on other cancer types.

CONCLUSIONS

While there is growing acknowledgement that weight management interventions in cancer survivors are needed, it is important to recognize that changes in both behavioral (EI, physical activity EE) and passive (resting EE, thermic effect of food) components of energy balance may occur post-diagnosis. This information can help to inform weight management interventions which often entail modifications in diet and/or physical activity.

Feeding Neurons Integrate Metabolic and Reproductive States in Mice

Trade-offs between metabolic and reproductive processes are important for survival, particularly in mammals that gestate their young. Puberty and reproduction, as energetically taxing life stages, are often gated by metabolic availability in animals with ovaries. How the nervous system coordinates these trade-offs is an active area of study. We identify somatostatin neurons of the tuberal nucleus (TNSST) as a node of the feeding circuit that alters feeding in a manner sensitive to metabolic and reproductive states in mice. Whereas chemogenetic activation of TNSST neurons increased food intake across sexes, selective ablation decreased food intake only in female mice during proestrus. Interestingly, this ablation effect was only apparent in animals with a low body mass. Fat transplantation and bioinformatics analysis of TNSST neuronal transcriptomes revealed white adipose as a key modulator of the effects of TNSST neurons on food intake. Together, these studies point to a mechanism whereby TNSST hypothalamic neurons modulate feeding by responding to varying levels of circulating estrogens differentially based on energy stores. This research provides insight into how neural circuits integrate reproductive and metabolic signals, and illustrates how gonadal steroid modulation of neuronal circuits can be context-dependent and gated by metabolic status.

Moving beyond the mean: Promising research pathways to support a precision medicine approach to hormonal contraception

Women's psychological and behavioral responses to hormonal contraceptive (HC) treatment can be highly variable. One of the great challenges to researchers seeking to improve the experiences of women who use HCs is to identify the sources of this variability to minimize unpleasant psychobehavioral side-effects. In the following, we provide recommendations for programs of research aimed at identifying sources of heterogeneity in women's experiences with HC. First, we review research demonstrating person- and prescription- based heterogeneity in women's psychobehavioral responses to HCs. Next, we identify several promising person- and prescription- based sources of this heterogeneity that warrant future research. We close with a discussion of research approaches that are particularly well-suited to address the research questions raised in article. Together, this review provides researchers with several promising research pathways to help support the development of a precision medicine approach to HC treatment.

A longitudinal assessment of appetite loss and nutritional care among postoperative patients in Vietnam

Background

Post-operative appetite loss is an important complication affecting surgical outcomes. It has been estimated that nearly 60% of patients having gastrointestinal or major elective surgeries suffer from malnutrition. Appetite refers to the physical desire for food appetite, and losing appetite after surgery may result in a decrease in body weight, impairment of intestinal absorption and eventually, malnutrition among postoperative patients. This study aims to assess appetite status and other relevant factors among abdominal postoperative patients in Vietnam.

Methods

A cross-sectional study was conducted on 169 abdominal postoperative patients from June 1st to August 30th, 2016 at Hanoi Medical University Hospital, Hanoi, Vietnam. Appetite score was computed by using the Council on Nutrition Appetite Questionnaire (CNAQ). This study used GEE to account for the potential correlation of outcomes of the longitudinal assessment, assuming an independent correlation structure.

Results

The primary and secondary outcome measures: highest average appetite score was recorded in the preoperative day and the score declined throughout seven-day duration. Patients who were female, under general anesthetics and being under open surgery tended to get lower appetite scores. The majority of patients had moderate to good appetite in both the preoperative day and seven days post-operation.

Conclusion

Women should receive more care and help in regaining their appetite after surgery. Treatment for appetite loss through non-pharmaceutical measures should be prioritized. Interventions that increase the appetite of patients after abdominal surgery should be targeted on patients being under general anesthetic as well as open surgery and be undertaken with caution.

Estradiol-dependent hypocretinergic/orexinergic behaviors throughout the estrous cycle

RATIONALE

The female menstrual or estrous cycle and its associated fluctuations in circulating estradiol (E2), progesterone, and other gonadal hormones alter orexin or hypocretin peptide production and receptor activity. Depending on the estrous cycle phase, the transcription of prepro-orexin mRNA, post-translational modification of orexin peptide, and abundance of orexin receptors change in a brain region-specific manner. The most dramatic changes occur in the hypothalamus, which is considered the starting point of the hypothalamic-pituitary-gonadal axis as well as the hub of orexin-producing neurons. Thus, hypothalamus-regulated behaviors, including arousal, feeding, reward processing, and the stress response depend on coordinated efforts between E2, progesterone, and the orexin system. Given the rise of orexin therapeutics for various neuropsychiatric conditions including insomnia and affective disorders, it is important to delineate the behavioral outcomes of this drug class in both sexes, as well as within different time points of the female reproductive cycle.

OBJECTIVES

Summarize how the menstrual or estrous cycle affects orexin system functionality in animal models in order to predict how orexin pharmacotherapies exert varying degrees of behavioral effects across the dynamic hormonal milieu.

The importance of estradiol for body weight regulation in women

Obesity in women of reproductive age has a number of adverse metabolic effects, including Type II Diabetes (T2D), dyslipidemia, and cardiovascular disease. It is associated with increased menstrual irregularity, ovulatory dysfunction, development of insulin resistance and infertility. In women, estradiol is not only critical for reproductive function, but they also control food intake and energy expenditure. Food intake is known to change during the menstrual cycle in humans. This change in food intake is largely mediated by estradiol, which acts directly upon anorexigenic and orexigenic neurons, largely in the hypothalamus. Estradiol also acts indirectly with peripheral mediators such as glucagon like peptide-1 (GLP-1). Like estradiol, GLP-1 acts on receptors at the hypothalamus. This review describes the physiological and pathophysiological mechanisms governing the actions of estradiol during the menstrual cycle on food intake and energy expenditure and how estradiol acts with other weight-controlling molecules such as GLP-1. GLP-1 analogs have proven to be effective both to manage obesity and T2D in women. This review also highlights the relationship between steroid hormones and women's mental health. It explains how a decline or imbalance in estradiol levels affects insulin sensitivity in the brain. This can cause cerebral insulin resistance, which contributes to the development of conditions such as Parkinson's or Alzheimer's disease. The proper use of both estradiol and GLP-1 analogs can help to manage obesity and preserve an optimal mental health in women by reducing the mechanisms that trigger neurodegenerative disorders.

Food preferences throughout the menstrual cycle - A computer-assisted neuro-endocrino-psychological investigation

BACKGROUND

As eating behavior changes in relation to the menstrual cycle and weight changes with menopausal transition, ovarian hormones appear to be involved in regulating eating behavior. However, observations are contradictory and are difficult to compare, due to methodological problems related to nutritional epidemiology. To better understand the relationship between ovarian steroid hormones and eating behavior, our study evaluates women's responses to visual food cues at different points in the menstrual cycle with their specific serum estrogen/progesterone levels and women's responses in the case of strong estrogen changes in the context of fertility treatments.

METHODS

We collected data from 129 women, 44 of whom received in vitro fertilization (IVF) at the Department of Reproductive Endocrinology, University Hospital Zurich. A total of 85 women with natural cycles were recruited at the University Hospital Zurich (n = 37) and at the Hannover Medical School (n = 48). Our observational study used 4 different measurement time points across the natural cycle and 2 measurement time points in women with supraphysiological estradiol levels during fertility treatments. Using a second cycle, we then tested our results for replication. At these predefined time points, women were shown pictures of 11 categories of food, with 4 items for each category and blood samples for measurement of hormone levels were taken. Food preferences registered at the time of the investigation were indicated on a visual analogue scale (0-100).

RESULTS

We did not find any statistically significant association between women's serum hormone levels and the rating of visually presented food, either during the menstrual cycle or during fertility treatments after controlling for multiple testing (all p > 0.005). Ratings for fruits, vegetables, and carbohydrates showed a significant linear decline throughout the first menstrual cycle (p < 0.01), which did not replicate in the second cycle (p > 0.05). In contrast, the ratings for sweets showed a significant linear decline in both cycles (both p < 0.01), with a mean rating of 54.2 and 48.8 in the menstrual phase of the first and second cycle, respectively, to a mean rating of 47.7 and 43.4 in the premenstrual phase of the first and second cycle, respectively. During fertility treatments, no food rating showed a significant change (all p > 0.05). Mood such as negative and positive affects did not influence ratings for visual food cues neither throughout the menstrual cycles nor during fertility treatment.

CONCLUSIONS

Serum levels of estradiol and progesterone do not correlate with food ratings in women, even when estradiol levels are above the physiological level of a natural menstrual cycle. Since, except for sweets, significant changes in food ratings in a first cycle did not replicate in a second menstrual cycle, significant findings from the literature based on animal or human studies focusing on a single-cycle have to be interpreted with caution.

Modeling hormonal contraception in female rats: A framework for studies in behavioral neurobiology

Research on hormonal contraceptives (HC) in animal models is lacking, and as a result, so is our understanding of the impact of HC on the brain and behavior. Here, we provide a review of the pharmacology of HC, as well as the methodology and best practices for designing a model of HC in female rats. We outline specific methodological considerations regarding dosing, route of administration, exposure time/timing, and selecting a control group. We also provide a framework outlining important levels of analysis for thinking about the impact of HC on behavioral and neurobiological outcomes. The purpose of this review is to equip researchers with foundational knowledge, and some basic elements of experimental design for future studies investigating the impact of HC on the brain and behavior of female rats.

Experimental Exposure to Tebuconazole Affects Metabolism and Body Condition in a Passerine Bird, the House Sparrow (Passer domesticus)

Triazole compounds are among the most widely used fungicides in agroecosystems to protect crops from potential fungal diseases. Triazoles are suspected to have an impact on nontarget species due to their interactions with nonfungal sterol synthesis, and wild birds are likely to be contaminated by triazole fungicides because many of them live in agroecosystems. We experimentally tested whether exposure to environmental concentrations of a triazole could alter key integrative traits (metabolic rates and body condition) of an agroecosystem sentinel species, the house sparrow (Passer domesticus). Wild-caught adult sparrows were maintained in captivity and exposed (exposed group) or not (control group) for 7 continuous months to tebuconazole through drinking water. The metabolic rates of exposed and control sparrows were then measured at two different temperatures (12 °C and 25 °C), which correspond, respectively, to the thermoregulation and thermoneutrality temperatures of this species. We found that exposed sparrows had lower resting metabolic rates (i.e., measured at thermoneutrality, 25 °C) than controls. However, the thermoregulatory metabolic rates (i.e., measured at 12 °C) did not differ between exposed and control sparrows. Although the body mass and condition were not measured at the beginning of the exposure, sparrows at the time of the metabolic measurements 7 months after the onset of such exposure had a higher body condition than controls, supporting further the idea that tebuconazole affects metabolic functions. Our study demonstrates for the first time that the use of tebuconazole can alter metabolism and could potentially lead to adverse effects in birds. Environ Toxicol Chem 2022;41:2500-2511. © 2022 SETAC.

Sex as a Biological Variable in Nutrition Research: From Human Studies to Animal Models

Biological sex is a fundamental source of phenotypic variability across species. Males and females have different nutritional needs and exhibit differences in nutrient digestion and utilization, leading to different health outcomes throughout life. With personalized nutrition gaining popularity in scientific research and clinical practice, it is important to understand the fundamentals of sex differences in nutrition research. Here, we review key studies that investigate sex dimorphism in nutrition research: sex differences in nutrient intake and metabolism, sex-dimorphic response in nutrient-restricted conditions, and sex differences in diet and gut microbiome interactions. Within each area above, factors from sex chromosomes, sex hormones, and sex-specific loci are highlighted.

Attentional bias towards appealing and disgusting food cues varies with the menstrual cycle

Ovarian hormonal changes along the female menstrual cycle are believed to adapt women to the external environment through various adaptive strategies, including modulating appetite and eating behavior. We aimed to compare food-associated behavioral responses between two distinct menstrual phases (late follicular vs. mid-luteal) and investigate the underlying neural mechanism. Attentional bias towards visual food cues was repeatedly measured in 29 healthy young women during these two menstrual phases in a counterbalanced manner. Combining an emotional dot-probe task with frequency-tagged electroencephalography (EEG), we confirmed that the menstrual cycle modulated healthy women's attentional bias towards appealing and disgusting food cues. Women in the mid-luteal phase showed more avoidance of disgusting food cues, as reflected by a significantly longer response time. Steady-state visual evoked potential (SSVEP) results indicated that they exhibited a trend of transiently enhanced attentional bias towards appealing food cues and another trend of speeded attentional withdrawal from disgusting food cues during the mid-luteal phase relative to the late follicular phase, albeit non-significant after correction for multiple testing. Moreover, a significantly larger P3 amplitude was evoked by probes following the presentation of disgusting food cues in the mid-luteal phase than the late follicular phase. These findings indicate divergent attentional deployments on emotional food cues across menstrual phases and suggest the mid-luteal phase as a relatively sensitive stage in the menstrual cycle for women to regulate their appetite and eating behavior.

Risk for midlife psychosis in women: critical gaps and opportunities in exploring perimenopause and ovarian hormones as mechanisms of risk

Women show a heightened risk for psychosis in midlife that is not observed in men. The menopausal transition (i.e. perimenopause) and accompanying changes in ovarian hormones are theorized to account for this midlife increase in risk. This narrative review aims to empirically examine these theories by reviewing studies of midlife and perimenopausal psychosis risk in women and potential ovarian hormone mechanisms of effects. Clinical and pre-clinical studies examining the effects of midlife age, menopausal stage, and ovarian hormones across adulthood on psychosis risk were identified. Synthesis of this body of work revealed that the peak ages of midlife psychosis risk in women overlap with the age range of key menopausal stages (especially the perimenopausal transition), although studies directly assessing menopausal stage are lacking. Studies examining ovarian hormone effects have almost exclusively focused on earlier developmental stages and events (e.g. pregnancy, the menstrual cycle) and show increases in psychotic symptoms in women and female rats during periods of lower estradiol levels. Estrogen treatment also tends to enhance the effects of neuroleptics in females across species at various reproductive phases. Initial data are promising in suggesting a role for menopausal stage and ovarian hormones in psychosis risk. However, critical gaps in our knowledge base remain, as there is a tendency to rely on indirect and proxy measures of menopausal status and hormones. Opportunities for future research are discussed with the goal of increasing research in this critical area of women's health.

Glial cells as integrators of peripheral and central signals in the regulation of energy homeostasis

Communication between the periphery and the brain is key for maintaining energy homeostasis. To do so, peripheral signals from the circulation reach the brain via the circumventricular organs (CVOs), which are characterized by fenestrated vessels lacking the protective blood-brain barrier (BBB). Glial cells, by virtue of their plasticity and their ideal location at the interface of blood vessels and neurons, participate in the integration and transmission of peripheral information to neuronal networks in the brain for the neuroendocrine control of whole-body metabolism. Metabolic diseases, such as obesity and type 2 diabetes, can disrupt the brain-to-periphery communication mediated by glial cells, highlighting the relevance of these cell types in the pathophysiology of such complications. An improved understanding of how glial cells integrate and respond to metabolic and humoral signals has become a priority for the discovery of promising therapeutic strategies to treat metabolic disorders. This Review highlights the role of glial cells in the exchange of metabolic signals between the periphery and the brain that are relevant for the regulation of whole-body energy homeostasis.