Lactation improves pancreatic β cell mass and function through serotonin production

Serum from pregnant donors induces human beta cell proliferation

Pancreatic beta cells are among the slowest replicating cells in the human body and have not been observed to increase in number except during the fetal and neonatal period, in cases of obesity, during puberty, as well as during pregnancy. Pregnancy is associated with increased beta cell mass to meet heightened insulin demands. This phenomenon raises the intriguing possibility that factors present in the serum of pregnant individuals may stimulate beta cell proliferation and offer insights into expansion of the beta cell mass for treatment and prevention of diabetes. The primary objective of this study was to test the hypothesis that serum from pregnant donors contains bioactive factors capable of inducing human beta cell proliferation. An immortalized human beta cell line with protracted replication (EndoC-βH1) was cultured in media supplemented with serum from pregnant and non-pregnant female and male donors and assessed for differences in proliferation. This experiment was followed by assessment of proliferation of primary human beta cells. Sera from five out of six pregnant donors induced a significant increase in the proliferation rate of EndoC-βH1 cells. Pooled serum from the cohort of pregnant donors also increased the rate of proliferation in primary human beta cells. This study demonstrates that serum from pregnant donors stimulates human beta cell proliferation. These findings suggest the existence of pregnancy-associated factors that can offer novel avenues for beta cell regeneration and diabetes prevention strategies. Further research is warranted to elucidate the specific factors responsible for this effect.

Gestational Diabetes Mellitus, Breastfeeding, and Progression to Type 2 Diabetes: Why Is It So Hard to Achieve the Protective Benefits of Breastfeeding? A Narrative Review

Women diagnosed with gestational diabetes mellitus (GDM) face a significantly heightened risk of developing type 2 diabetes mellitus (T2DM) later in life. Breastfeeding (BF) has been identified as a potential strategy to delay or prevent T2DM; however, women with GDM often encounter barriers in initiating and maintaining adequate BF practices compared to those with uncomplicated pregnancies. This paradox prompts an exploration into the causes of these BF challenges and considers the possibility of reverse causation: Does prolonged and intensive BF mitigate the risk of subsequent glucose dysregulation and T2DM? Alternatively, do women with compromised insulin secretion and sensitivity, who are predisposed to T2DM, struggle to sustain intensive BF practices? This narrative review aims to explore the interplay between GDM, BF, and T2DM development by examining the different factors that present BF challenges among women with GDM. Understanding these dynamics is crucial for establishing realistic BF expectations and developing effective clinical and public health strategies to support BF in this high-risk population.

Improvements in Insulin Resistance and Glucose Metabolism Related to Breastfeeding Are Not Mediated by Subclinical Inflammation

Background: Lactation is known to improve insulin resistance, but this phenomenon remains poorly understood. Our goal was to evaluate whether subclinical inflammation could mediate the association between breastfeeding (BF) and improvement in glucose metabolism and markers of insulin resistance (MIRs) in the postpartum. Methods: A total of 95 adult women (≥18 years) with a BMI ≥ 25 kg/m2 from the outpatient clinic of the Federal University of São Paulo were followed from early pregnancy until 60 to 180 days postpartum. The patients were divided based on their BF status: BF and non-BF groups. A latent variable termed SubInf was created incorporating inflammation-related biomarkers: adiponectin, E-selectin, branched-chain amino acids, zonulin, copeptin, and lipopolysaccharides. The association of BR with MIRs in the postpartum was evaluated through linear regression analysis, and mediation analysis was performed to evaluate the role of SubInf in this association. Results: The groups were similar regarding gestational diabetes mellitus (GDM) prevalence, pre-gestational BMI, caloric intake, physical activity, and postpartum weight loss. The BF group presented lower levels of triglycerides (TGs), fasting glucose, fasting insulin, TG/HDLcholesterol ratio (TG/HDL), TyG index, and HOMA-IR compared to the non-BF group. A linear regression analysis adjusted for scholarity, parity, pre-gestational BMI, GDM, weight gain during pregnancy, and mode of delivery revealed an inverse association between BF and fasting glucose [-6.30 (-10.71 to -1.89), p = 0.005), HOMA-IR [-0.28 (-0.50 to -0.05), p = 0.017], TyG index [-0.04 (-0.06 to -0.01), p = 0.002], and TG/HDL ratio [-0.23 (-0.46 to -0.01), p = 0.001]. In the mediation analysis, SubInf did not mediate the indirect effect of BF on MIRs. Conclusions: In overweight and obese women, an association between BF and improvement in MIRs in the postpartum was seen, corroborating that BF should be stimulated, especially in these cardiometabolic high-risk women. Subclinical inflammation did not seem to mediate this association.

Comparison Between SGLT2 Inhibitors and Lactation: Implications for Cardiometabolic Health in Parous Women

Sodium-glucose cotransporter-2 (SGLT2) inhibition and lactation result in the excretion of large amounts of glucose in urine or milk and are associated with a lower risk of cardiovascular events. The respective mechanisms behind this association with cardiovascular protection are not clear. This review compares the contribution of noninsulin-mediated glucose transport during pharmacologic inhibition of SGLT2 with noninsulin-mediated glucose transport during lactation in terms of the implications for the cardiometabolic health of parous women. The search topics used to obtain information on SGLT2 inhibitors included mechanisms of action, atherosclerosis, and heart failure. The search topics used to obtain information on lactation included cardiovascular health and milk composition. Subsequent reference searches of retrieved articles were also used. Active treatment with SGLT2 inhibitors affects glucose and sodium transport in the kidneys and predominantly protects against hospitalization for heart failure soon after the onset of therapy. Active lactation stimulates glucose transport into the mammary gland and improves subclinical and clinical atherosclerotic vascular disease years after delivery. Both SGLT2 inhibitors and lactation have effects on a variety of glucose transporters. Several mechanisms have been proposed to explain the cardiometabolic benefits of SGLT2 inhibition and lactation. Learning from the similarities and differences between both processes will advance our understanding of cardiometabolic health for all people.

High-risk pregnancy and risk of breastfeeding failure

BACKGROUND

There is growing evidence that supports the role of breastfeeding in reducing the burden of non-communicable diseases (NCDs). There are considerable gaps in breastfeeding outcomes in mothers with chronic diseases due to a lack of knowledge and support in the postpartum period. Mothers who have NCDs and pregnancy complications are at risk of breastfeeding failure.

AIM

To compare breastfeeding outcomes in mothers with NCDs with healthy mothers and determine the underlying challenges that lead to poor outcomes.

METHODS

A prospective cohort study was conducted among 150 women (50 with high-risk pregnancies (HRP) and 100 with normal pregnancies (NP)). They were recruited from those attending the immunization and outpatient clinics at Sohag General Hospital. Mothers were recruited at 34 weeks gestation and were followed up at 2 weeks, 6 weeks, and 6 months after delivery. A pretested and validated questionnaire was used to collect detailed epidemiological, personal, health-related status, medications, hospitalizations, reproductive history, current delivery, and previous breastfeeding experiences. On follow-up they were assessed for breastfeeding practices, their health and health and growth of their children, and social support.

RESULTS

Delivery by cesarean section and postpartum bleeding were commoner among HRP patients. Initiation of breastfeeding in the 1st hour of delivery was significantly lower among women with HRP than those with normal pregnancies (48.0% versus 71.0%, p = 0.006). The most common reason for not initiating breastfeeding among the NP group was insufficient milk (34.5%), while in the HRP group, it was the mother's illness (80.8%). Skin-to-skin contact with the baby after birth was significantly less practiced in the HRP than in the NP group (38.0% vs 64.0% at p = 0.003). Herbs (such as cumin, caraway, cinnamon, aniseed, and chamomile) were the most common pre-lacteal feeds offered (63.0% in NP vs 42.0% in HRP). Artificial milk was more used in HRP than NP (24.0% vs 4.0%). Breast engorgement was 3 times more common in the HRP compared to the NP group (61.5% vs19.6%). Stopping breastfeeding due to breast problems was 2.5 times higher in the HRP than in the NP group (38.5% vs. 15.2%, p = 0.003). Nipple fissures were twice as common among the NP than among the HRP group ((73.0%) vs. (38.5%), p = 0.026). Exclusive breastfeeding during the period of follow-up was lower in the HRP than in the NP group (40.0% vs 61.0%, p < 0.05) and formula feeding was twice as common in the HRP as in the NP group (34.0% vs. 18.0%, p = 0.015). Child illness was significantly higher among women with HRP than those with NP (66.0% vs 48.0%, p = 0.037).

CONCLUSIONS

Women with HRP are at a high risk of poor breastfeeding outcomes with increased lactation problems and formula feeding rates. Encouraging women especially those with HRP to achieve optimal breastfeeding practices is a simple intervention that can be included in daily practice and may have a positive impact on mothers' health.

The hormonal mechanism of the effects of meperidine, sertraline, tianeptine, and their combinations on reproductive functions in female rats

BACKGROUND

Infertility caused by drugs that inhibit serotonin reuptake has been attributed to serotonin toxicity. Serotonin has been linked to cause a rise in prolactin and cortisol. This study examined the effects of meperidine, sertraline, tianeptine and combinations on female rat reproductive function.

METHODS

Female rats were split into 8 groups (n=7): healthy control (HG), meperidine (MG), sertraline (SG), tianeptine (TG), meperidine+sertraline (MSG), meperidine+tianeptine (MTG), sertraline+tianeptine (STG), meperidine+sertraline+tianeptine (MSTG). Meperidine (20 mg/kg, 2×1) was injected intramuscularly. Sertraline (30 mg/kg, 1×1) and tianeptine (5 mg/kg, 1×1) were given orally. The HG received distilled water as solvent. Treatments continued for 20 days. Then, adult males were added to the rat groups and drug treatment continued for another five days. Blood samples were collected on day 26 for biochemical tests.

RESULTS

Total oxidant status (TOS) and total antioxidant status (TAS) were not statistically significant between groups (p>0.05). Meperidine (p<0.001) and sertraline (p<0.001) alone increased prolactin levels in comparison to HG and tianeptine inhibited the increase (p<0.001). While meperidine increased corticosterone levels versus HG (p<0.001), sertraline and tianeptine were close to HG (p>0.05). Number of infertile animals was 6 for meperidine, 3 for sertraline, and none for tianeptine. While the duration of pregnancy in MG (15 days) and SG (15 days) was longer compared to HG (2.86 days), no change was observed in TG (2.5 days).

CONCLUSION

Tianeptine and other serotonin re-uptake stimulants may be useful in the treatment of reproductive dysfunction and infertility due to serotonin re-uptake inhibitor treatment.

A Century of Prolactin: Emerging Perspectives as a Metabolic Regulator

Prolactin, a hormone that has been studied for almost a century, has evolved from a reproductive regulator to a key player in metabolic health. Initially identified for its lactogenic role, the impact of prolactin on glucose and lipid metabolism became evident in the 1970s, leading to a paradigm shift in our understanding. Deviations in prolactin levels, including hyperprolactinaemia and hypoprolactinaemia, have been associated with adverse effects on glucose and lipid metabolism. Mechanistically, prolactin regulates metabolic homoeostasis by maintaining islet abundance, regulating the hypothalamic energy regulatory centre, balancing adipose tissue expansion, and regulating hepatic metabolism. Given the widespread use of pharmaceutical agents that affect prolactin levels, it is important to examine prolactin-related metabolic effects. Recently, a profound exploration of the intricate metabolic role of prolactin has been conducted, encompassing its rhythm-dependent regulatory influence on metabolism and its correlation with cognitive impairment associated with metabolic diseases. In this review, we highlight the role of prolactin as a metabolic regulator, summarise its metabolic effects, and discuss topics related to the association between prolactin and metabolic comorbidities.

Pancreatic islet adaptation in pregnancy and postpartum

Pancreatic islets, particularly insulin-producing β-cells, are central regulators of glucose homeostasis capable of responding to a variety of metabolic stressors. Pregnancy is a unique physiological stressor, necessitating the islets to adapt to the complex interplay of maternal and fetal-placental factors influencing the metabolic milieu. In this review we highlight studies defining gestational adaptation mechanisms within maternal islets and emerging studies revealing islet adaptations during the early postpartum and lactation periods. These include adaptations in both β and in 'non-β' islet cells. We also discuss insights into how gestational and postpartum adaptation may inform pregnancy-specific and general mechanisms of islet responses to metabolic stress and contribute to investigation of gestational diabetes.

5-Methoxy-2-aminoindane Reverses Diet-Induced Obesity and Improves Metabolic Parameters in Mice: A Potential New Class of Antiobesity Therapeutics

The escalating prevalence of obesity and its related disorders represents a daunting global health challenge. Unfortunately, current pharmacological interventions for obesity remain limited and are often associated with debilitating side effects. Against this backdrop, the psychoactive aminoindane derivative 5-methoxy-2-aminoindane (MEAI) has gained considerable attention for its ability to induce a pleasurable, alcohol-like sensation while curbing alcohol consumption. Given the potential impact of MEAI on food addiction and energy homeostasis, we examined its metabolic efficacy on appetite regulation, obesity, and related comorbidities under acute and chronic settings, utilizing a mouse model of diet-induced obesity (DIO). Our results demonstrated that MEAI treatment significantly reduced DIO-induced overweight and adiposity by preserving lean mass and decreasing fat mass. Additionally, MEAI treatment exhibited positive effects on glycemic control by attenuating DIO-induced hyperglycemia, glucose intolerance, and hyperinsulinemia. Furthermore, MEAI reduced DIO-induced hepatic steatosis by decreasing hepatic lipid accumulation and lowering liver triglyceride and cholesterol levels, primarily by inhibiting de novo lipid synthesis. Metabolic phenotyping revealed that MEAI increased energy expenditure and fat utilization while maintaining food consumption similar to that of the vehicle-treated group. Lastly, MEAI normalized voluntary locomotion actions without any overstimulatory effects. These findings provide compelling evidence for the antiobesity effects of MEAI treatment and call for further preclinical testing. In conclusion, our study highlights the potential of MEAI as a novel therapeutic approach for treating obesity and its associated metabolic disorders, offering hope for the development of new treatment options for this global health challenge.

Pancreatic beta-cell mass and function and therapeutic implications of using antidiabetic medications in type 2 diabetes

Nowadays, the focus of diabetes treatment has switched from lowering the glucose level to preserving glycemic homeostasis and slowing the disease progression. The main pathophysiology of both type 1 diabetes and long-standing type 2 diabetes is pancreatic β-cell mass loss and dysfunction. According to recent research, human pancreatic β-cells possess the ability to proliferate in response to elevated insulin demands. It has been demonstrated that in insulin-resistant conditions in humans, such as obesity or pregnancy, the β-cell mass increases. This ability could be helpful in developing novel treatment approaches to restore a functional β-cell mass. Treatment strategies aimed at boosting β-cell function and mass may be a useful tool for managing diabetes mellitus and stopping its progression. This review outlines the processes of β-cell failure and detail the many β-cell abnormalities that manifest in people with diabetes mellitus. We also go over standard techniques for determining the mass and function of β-cells. Lastly, we provide the therapeutic implications of utilizing antidiabetic drugs in controlling the mass and function of pancreatic β-cells.

Prospective associations between breast feeding, metabolic health, inflammation and bone density in women with prior gestational diabetes mellitus

INTRODUCTION

The aim of the study is to investigate prospective associations between breastfeeding and metabolic outcomes, inflammation, and bone density in women with prior gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

We prospectively included 171 women with GDM from the MySweetheart trial. Women were followed during pregnancy (from 24 up to 32 weeks' gestational age) up to 1 year postpartum. Outcomes included weight, weight retention, body composition, insulin resistance and secretion indices, C reactive protein (CRP), and bone density. We compared differences in the associations between breastfeeding and health outcomes between women who breast fed <6 months vs ≥6 months. Analyses were adjusted for potential medical and sociodemographic confounders.

RESULTS

Breastfeeding initiation was 94.2% (n=161) and mean breastfeeding duration was 6.6 months. Breastfeeding duration was independently associated with lower weight, weight retention, body fat, visceral adipose tissue, lean mass, CRP, insulin resistance (Homeostatic Model Assessment for Insulin Resistance), and insulin secretion (Homeostatic Model Assessment of β-cell index) at 1 year postpartum (all p≤0.04) after adjusting for confounders. Breastfeeding was associated with higher insulin resistance-adjusted insulin secretion (Insulin Secretion-Sensitivity Index-2) in the unadjusted analyses only. There was no association between breastfeeding duration and bone density. Compared with <6 months, breastfeeding duration ≥6 months was associated with lower weight, weight retention, body fat, fat-free mass as well as lower CRP at 1 year postpartum (all p<0.05) after adjusting for confounders.

CONCLUSIONS

Longer breastfeeding duration among women with prior GDM was associated with lower insulin resistance, weight, weight retention, body fat and inflammation, but not lower bone density at 1 year postpartum. Breastfeeding for ≥6 months after GDM can help to improve cardiometabolic health outcomes 1 year after delivery.

An shRNA screen in primary human beta cells identifies the serotonin 1F receptor as a negative regulator of survival during transplant

Islet transplantation can cure type 1 diabetes, but peri-transplant beta cell death limits this procedure to those with low insulin requirements. Improving human beta cell survival or proliferation may make islet transplantation a possibility for more type 1 patients. To identify novel regulators of beta cell survival and proliferation, we conducted a pooled small hairpin RNA (shRNA) screen in primary human beta cells transplanted into immunocompromised mice. shRNAs targeting several cyclin dependent kinase inhibitors were enriched after transplant. Here, we focused on the Gi/o-coupled GPCR, serotonin 1F receptor ( HTR1F, 5-HT 1F ) which our screen identified as a negative regulator of beta cell numbers after transplant. In vitro , 5-HT 1F knockdown induced human beta cell proliferation but only when combined with harmine and exendin-4. In vivo , knockdown of 5-HT 1F reduced beta cell death during transplant. To demonstrate the feasibility of targeting 5-HT 1F in islet transplant, we identified and validated a small molecule 5-HT 1F antagonist. This antagonist increased glucose stimulated insulin secretion from primary human islets and cAMP accumulation in primary human beta cells. Finally, the 5-HT 1F antagonist improved glycemia in marginal mass, human islet transplants into immunocompromised mice. We identify 5-HT 1F as a novel druggable target to improve human beta cell survival in the setting of islet transplantation.

One Sentence Summary

Serotonin 1F receptor (5-HT 1F ) negatively regulates insulin secretion and beta cell survival during transplant.

Lifetime Duration of Breastfeeding and Cardiovascular Risk in Women With Type 2 Diabetes or a History of Gestational Diabetes: Findings From Two Large Prospective Cohorts

OBJECTIVE

Breastfeeding duration is inversely associated with risks of cardiovascular disease (CVD) and type 2 diabetes in parous women. However, the association among women at high risk, including women with type 2 diabetes or gestational diabetes mellitus (GDM) is unclear.

RESEARCH DESIGN AND METHODS

We included 15,146 parous women with type 2 diabetes from the Nurses' Health Study I and II (NHS, NHS II) and 4,537 women with a history of GDM from NHS II. Participants reported history of breastfeeding via follow-up questionnaires. Incident CVD by 2017 comprised stroke or coronary heart disease (CHD) (myocardial infarction, coronary revascularization). Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox models.

RESULTS

We documented 1,159 incident CVD cases among women with type 2 diabetes in both cohorts during 188,874 person-years of follow-up and 132 incident CVD cases among women with a GDM history during 100,218 person-years of follow-up. Longer lifetime duration of breastfeeding was significantly associated with lower CVD risk among women with type 2 diabetes, with pooled aHR of 0.68 (95% CI 0.54-0.85) for >18 months versus 0 months and 0.94 (0.91-0.98) per 6-month increment in breastfeeding. Similar associations were observed with CHD (pooled aHR 0.93 [0.88-0.97]) but not with stroke (0.96 [0.91-1.02]) per 6-month increment in breastfeeding. Among women with GDM history, >18 months versus 0 months of breastfeeding was associated with an aHR of 0.49 (0.28-0.86) for total CVD.

CONCLUSIONS

Longer duration of breastfeeding was associated with lower risk of CVD in women with type 2 diabetes or GDM.

Monoamines' role in islet cell function and type 2 diabetes risk

The two monoamines serotonin and melatonin have recently been highlighted as potent regulators of islet hormone secretion and overall glucose homeostasis in the body. In fact, dysregulated signaling of both amines are implicated in β-cell dysfunction and development of type 2 diabetes mellitus (T2DM). Serotonin is a key player in β-cell physiology and plays a role in expansion of β-cell mass. Melatonin regulates circadian rhythm and nutrient metabolism and reduces insulin release in human and rodent islets in vitro. Herein, we focus on the role of serotonin and melatonin in islet physiology and the pathophysiology of T2DM. This includes effects on hormone secretion, receptor expression, genetic variants influencing β-cell function, melatonin treatment, and compounds that alter serotonin availability and signaling.

Influence of Breastfeeding on the State of Meta-Inflammation in Obesity-A Narrative Review

Obesity has become an emerging health issue worldwide that continues to grow in females of reproductive age as well. Obesity, as a multisystem and chronic disease, is associated with metabolic inflammation, which is defined as chronic low-grade systemic inflammation mediated by, i.a., adipose tissue macrophages. Lactation has been proven to have a beneficial influence on maternal health and could help restore metabolic balance, especially in the state of maternal obesity. In this review, we aimed to analyze the influence of breastfeeding on chronic low-grade meta-inflammation caused by obesity. We performed a comprehensive literature review using the PubMed, Science Direct, and Google Scholar electronic databases. For this purpose, we searched for "metabolic inflammation"; "meta-inflammation"; "obesity"; "breastfeeding"; "fetal programming"; "energy metabolism"; "postpartum"; "immunity"; "immune system"; and "inflammation" keyword combinations. While the clinical impact of breastfeeding on maternal and offspring health is currently well known, we decided to gain insight into more specific metabolic effects of adiposity, lipid, and glucose homeostasis, and immunological effects caused by the activity of cytokines, macrophages, and other immune system cells. Further research on the immunological and metabolic effects of breastfeeding in obese patients is key to understanding and potentially developing obesity therapeutic strategies.

Multiparity increases the risk of diabetes by impairing the proliferative capacity of pancreatic β cells

Pregnancy imposes a substantial metabolic burden on women, but little is known about whether or how multiple pregnancies increase the risk of maternal postpartum diabetes. In this study, we assessed the metabolic impact of multiple pregnancies in humans and in a rodent model. Mice that underwent multiple pregnancies had increased adiposity, but their glucose tolerance was initially improved compared to those of age-matched virgin mice. Later, however, insulin resistance developed over time, but insulin secretory function and compensatory pancreatic β cell proliferation were impaired in multiparous mice. The β cells of multiparous mice exhibited aging features, including telomere shortening and increased expression of Cdkn2a. Single-cell RNA-seq analysis revealed that the β cells of multiparous mice exhibited upregulation of stress-related pathways and downregulation of cellular respiration- and oxidative phosphorylation-related pathways. In humans, women who delivered more than three times were more obese, and their plasma glucose concentrations were elevated compared to women who had delivered three or fewer times, as assessed at 2 months postpartum. The disposition index, which is a measure of the insulin secretory function of β cells, decreased when women with higher parity gained body weight after delivery. Taken together, our findings indicate that multiple pregnancies induce cellular stress and aging features in β cells, which impair their proliferative capacity to compensate for insulin resistance.

Antidepressants and type 2 diabetes: highways to knowns and unknowns

Type 2 diabetes (T2D) is a metabolic disease caused by the development of insulin resistance (IR), relative insulin deficiency, and hyperglycemia. Hyperglycemia-induced neurochemical dysregulation activates the progression of depression in T2D patients. Therefore, management of depression by antidepressant agents improves glucose homeostasis and insulin sensitivity. However, prolong use of antidepressant drugs may increase the risk for the development of T2D. However, there is strong controversy concerning the use of antidepressant drugs in T2D. Therefore, this review try to elucidate the potential effects of antidepressant drugs in T2D regarding their detrimental and beneficial effects.

Prolactin does not seem to mediate the improvement on insulin resistance markers and blood glucose levels related to breastfeeding

Introduction

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. Strategies to decrease this risk should be strongly encouraged. Lactation has been associated, for the mother, with reduction in future T2DM risk in several studies. The mechanisms behind this phenomenon, however, are poorly understood. The aims of this study were, first, to compare blood glucose levels and markers of insulin resistance (MIR) in early postpartum women with overweight/obesity according to their breastfeeding status and, second, to evaluate whether prolactin (PRL) levels could mediate improvements in these parameters.

Methods

The prospective study followed 95 women older than 18 years from early pregnancy for up to 60 to 180 days postpartum. All participants had a BMI > 25 kg/m2 and a singleton pregnancy. At each visit, questionnaires and clinical and biochemical evaluations were performed. Participants were divided into two groups according to the breastfeeding status as "yes" for exclusive or predominant breastfeeding, and "no" for not breastfeeding.

Results

Breastfeeding women (n = 44) had significantly higher PRL levels [47.8 (29.6-88.2) vs. 20.0 (12.0-33.8), p< 0.001]. They also had significantly lower fasting blood glucose levels [89.0 (8.0) vs. 93.9 (12.6) mg/dl, p = 0.04], triglycerides (TG) [92.2 (37.9) vs. 122.4 (64.4) mg/dl, p = 0.01], TG/HDL ratio [1.8 (0.8) vs. 2.4 (1.6) mg/dl, p = 0.02], TyG index [8.24 (0.4) vs. 8.52 (0.53), p = 0.005], fasting serum insulin [8.9 (6.3-11.6) vs. 11.4 (7.7-17.0), p = 0.048], and HOMA-IR [2.0 (1.3-2.7) vs. 2.6 (1.6-3.9), p = 0.025] in the postpartum period compared to the non-breastfeeding group. Groups were homogeneous in relation to prevalence of GDM, pre-gestational BMI, as well as daily caloric intake, physical activity, and weight loss at postpartum. Linear regression analysis with adjustments for confounders showed a statistically significant association of breastfeeding with fasting blood glucose [-6.37 (-10.91 to -1.83), p = 0.006], HOMA-IR [-0.27 (-0.51 to -0.04), p = 0.024], TyG index [-0.04 (-0.06 to -0.02), p = 0.001], and TG/HDL ratio [-0.25 (-0.48 to -0.01), p = 0.038]. Mediation analysis showed that PRL did not mediate these effects. Sensitivity analyses considering different cutoffs for PRL levels also did not show modification effect in the mediation analyses.

Conclusion

Breastfeeding was associated with improvement in glucose metabolism and MIR 60 to 180 days after birth in overweight and obese women, even when adjusted for confounders. PRL levels were not found to mediate the association between breastfeeding and improvement in MIR.

NRF2 Dysregulation in Mice Leads to Inadequate Beta-Cell Mass Expansion during Pregnancy and Gestational Diabetes

The late stages of the mammalian pregnancy are accompanied with increased insulin resistance due to the increased glucose demand of the growing fetus. Therefore, as a compensatory response to maintain the maternal normal blood glucose levels, maternal beta-cell mass expands leading to increased insulin release. Defects in beta-cell adaptive expansion during pregnancy can lead to gestational diabetes mellitus (GDM). Although the exact mechanisms that promote GDM are poorly understood, GDM strongly associates with impaired beta-cell proliferation and with increased levels of reactive oxygen species (ROS). Here, we show that NRF2 levels are upregulated in mouse beta-cells at gestation day 15 (GD15) concomitant with increased beta-cell proliferation. Importantly, mice with tamoxifen-induced beta-cell-specific NRF2 deletion display inhibition of beta-cell proliferation, increased beta-cell oxidative stress and elevated levels of beta-cell death at GD15. This results in attenuated beta-cell mass expansion and disturbed glucose homeostasis towards the end of pregnancy. Collectively, these results highlight the importance of NRF2-oxidative stress regulation in beta-cell mass adaptation to pregnancy and suggest NRF2 as a potential therapeutic target for treating GDM.

The Incidence and Management of Type 2 Diabetes Mellitus After Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) refers to a transient state of impaired glucose tolerance that develops during pregnancy, affecting a significant proportion of expectant mothers globally. This review aimed to comprehensively examine the subsequent incidence and management of type 2 diabetes mellitus (T2DM) in women who have previously experienced GDM. The transition from GDM to T2DM is a well-recognized continuum, with affected women facing an increased risk of developing T2DM postpartum. Several studies have demonstrated that women with a history of GDM face a substantially higher risk of developing T2DM compared to normoglycemic pregnant women. The long-term consequences of developing T2DM following GDM are significant, as it not only affects the health of the mother but also poses risks to the offspring. The most common risk factors associated with the progression of GDM to T2DM include pregnancy at an advanced age, insulin treatment during pregnancy, and delivering an overweight baby. As GDM women are at higher risk of developing T2DM, effective management strategies such as lifestyle changes, postpartum care, breastfeeding, screening tests, and gaining awareness of risk are crucial to mitigate the risk of T2DM in this population. The current review was conducted to guide healthcare providers and women with a history of GDM about the potential risks of T2DM and management strategies to prevent the condition. This review provides a summary of evidence on the incidence rate of T2DM in GDM patients, its associated risk factors, and approaches to mitigate this challenge.

Understanding cell fate acquisition in stem-cell-derived pancreatic islets using single-cell multiome-inferred regulomes

Pancreatic islet cells derived from human pluripotent stem cells hold great promise for modeling and treating diabetes. Differences between stem-cell-derived and primary islets remain, but molecular insights to inform improvements are limited. Here, we acquire single-cell transcriptomes and accessible chromatin profiles during in vitro islet differentiation and pancreas from childhood and adult donors for comparison. We delineate major cell types, define their regulomes, and describe spatiotemporal gene regulatory relationships between transcription factors. CDX2 emerged as a regulator of enterochromaffin-like cells, which we show resemble a transient, previously unrecognized, serotonin-producing pre-β cell population in fetal pancreas, arguing against a proposed non-pancreatic origin. Furthermore, we observe insufficient activation of signal-dependent transcriptional programs during in vitro β cell maturation and identify sex hormones as drivers of β cell proliferation in childhood. Altogether, our analysis provides a comprehensive understanding of cell fate acquisition in stem-cell-derived islets and a framework for manipulating cell identities and maturity.

Freeze-dried powder of daylily bud improves bromocriptine-induced lactation disorder in rats via JAK2/STAT5 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Milk deficiency is a prevalent problem in the world. Daylily (Hemerocallis citrina Borani), called the Chinese mother flower, is a traditional vegetable and is believed to possess a galactagogue effect in China. Flavonoids and phenols are considered as the active ingredients of daylily to promote lactation and improve depression.

AIM OF THE STUDY

The aim of this study was to investigate the prolactin effects of freeze-dried powder of flower buds of H. citrina Baroni in rat and its action mechanisms.

MATERIALS AND METHODS

The chemical constituents of flower buds of H. citrina Baroni treated by different drying techniques were analyzed by ultrahigh pressure liquid chromatography-mass spectrometry. Sprague-Dawley (SD) rat model induced by bromocriptine was used to evaluate the effect of freeze-dried powder of daylily buds on promoting lactation. Network pharmacology method, ELISA, qPCR, and Western blot were used to clarify the action mechanisms.

RESULTS

We detected 657 compounds in daylily buds. The relative contents of total flavonoids and phenols in freeze-dried samples were higher than those in dried ones. Bromocriptine, as a dopamine receptor agonist, can significantly inhibit prolactin in rats. Daylily buds can restore the levels of prolactin, progesterone and estradiol depressed by bromocriptine, effectively improve the milk production of the rat, and promote the repair of rat mammary gland tissue. We analyzed the relationship between the chemical components of daylily buds and the genes related to lactation with network pharmacology method, revealing that flavonoids and phenols may be the active components that promoted milk production via JAK2/STAT5 pathway, which was confirmed by the results of qPCR and Western blot. Daylily buds can increase the mRNA expression of PRLR, CSN2, LALBA and FASN and the protein expression of PRLR, JAK2 and STAT5.

CONCLUSION

Daylily buds can improve the insufficient lactation of rats induced by bromocriptine through PRLR/JAK2/STAT5 pathway, and the freeze-dried processing method may better retain the active components of flavonoids and phenols that promote milk in daylily.

Pancreatic islet cell type-specific transcriptomic changes during pregnancy and postpartum

Pancreatic β-cell mass expands during pregnancy and regresses in the postpartum period in conjunction with dynamic metabolic demands on maternal glucose homeostasis. To understand transcriptional changes driving these adaptations in β-cells and other islet cell types, we performed single-cell RNA sequencing on islets from virgin, late gestation, and early postpartum mice. We identified transcriptional signatures unique to gestation and the postpartum in β-cells, including induction of the AP-1 transcription factor subunits and other genes involved in the immediate-early response (IEGs). In addition, we found pregnancy and postpartum-induced changes differed within each endocrine cell type, and in endothelial cells and antigen-presenting cells within islets. Together, our data reveal insights into cell type-specific transcriptional changes responsible for adaptations by islet cells to pregnancy and their resolution postpartum.

Serum from pregnant donors induces human beta cell proliferation and insulin secretion

Pancreatic beta cells are among the slowest replicating cells in the human body. Human beta cells usually do not increase in number with exceptions being during the neonatal period, in cases of obesity, and during pregnancy. This project explored maternal serum for stimulatory potential on human beta cell proliferation and insulin output. Gravid, full-term women who were scheduled to undergo cesarean delivery were recruited for this study. A human beta cell line was cultured in media supplemented with serum from pregnant and non-pregnant donors and assessed for differences in proliferation and insulin secretion. A subset of pregnant donor sera induced significant increases in beta cell proliferation and insulin secretion. Pooled serum from pregnant donors also increased proliferation in primary human beta cells but not primary human hepatocytes indicating a cell-type specific effect. This study suggests stimulatory factors in human serum during pregnancy could provide a novel approach for human beta cell expansion.

Maternal adaptations of the pancreas and glucose homeostasis in lactation and after lactation

During lactation, the maternal physiology adapts to bear the nutritional requirements of the offspring. The exocrine and endocrine pancreas are central to nutrient handling, promoting digestion and metabolism. In concert with prolactin, insulin is a determinant factor for milk synthesis. The investigation of the pancreas during lactation has been scattered over several periods. The investigations that laid the foundation of lactating pancreatic physiology and glucose homeostasis were conducted in the decades of 1970-1980. With the development of molecular biology, newer studies have revealed the molecular mechanisms involved in the endocrine pancreas during breastfeeding. There has been a surge of information recently about unexpected changes in the pancreas at the end of the lactation period and after weaning. In this review, we aim to gather information on the changes in the pancreas and glucose homeostasis during and after lactation and discuss the outcomes derived from the current discoveries.

Immunophenotypic and molecular characterization of pancreatic neuroendocrine tumors producing serotonin

Serotonin producing pancreatic neuroendocrine tumors (SP-PanNET) account for 0.58-1.4% of all pancreatic neuroendocrine tumors (PanNET). They may present with atypical symptoms, such as acute pancreatitis and are often radiologically characterized by main pancreatic duct dilatation. SP-PanNET are well differentiated neuroendocrine tumors (NET) distinct from classical PanNET by atypical serotonin secretion and abundant dense stroma deposition, like serotonin producing ileal NET leading in some cases to difficulties to reliably distinguish SP-PanNET from ileal NET metastases. The biology and molecular profile of SP-PanNET remain poorly characterized and the cell of origin within the pancreas is unclear. To address these questions, we analyzed a large cohort of SP-PanNET by immunohistochemistry (n = 29; ATRX, DAXX, MENIN, Islet1, PAX6, PDX1, ARX, CDX2), whole genome copy number array (Oncoscan™) and a large NGS panel (NovoPM™) (n = 10), FISH (n = 13) and RNA sequencing (n = 24) together with 21 ileal NET and 29 nonfunctioning PanNET (NF-PanNET). These analyses revealed a unique genomic profile with frequent isolated loss of chromosome 1 (14 cases-61%) and few pathogenic mutations (KMT2C in 2 cases, ARID1A in 1 case). Unsupervised RNAseq-based clustering showed that SP-PanNET were closer to NF-PanNET than ileal NET with an exclusive beta cell-like signature. SP-PanNET showed TGF-β pathway activation signatures associated with extracellular matrix remodeling and similar signature were reproduced in vitro when pancreatic stellate cells were exposed to serotonin. SP-PanNET immunohistochemical profile resemble that of ileal NET except for PDX1 and PAX6 expression to a lesser extend suggesting that these two markers may be useful to diagnose SP-PanNET. Taken together, this suggests that SP-PanNET are a very specific PanNET entity with a peculiar biology leading to the characteristic fibrotic aspect.

Higher Muscle Mass Protects Women with Gestational Diabetes Mellitus from Progression to Type 2 Diabetes Mellitus

BACKGROUND

We evaluated whether postpartum muscle mass affects the risk of type 2 diabetes mellitus (T2DM) in Korean women with gestational diabetes mellitus (GDM).

METHODS

A total of 305 women with GDM (mean age, 34.9 years) was prospectively evaluated for incident prediabetes and T2DM from 2 months after delivery and annually thereafter. Appendicular skeletal muscle mass (ASM) was assessed with bioelectrical impedance analysis at the initial postpartum visit, and ASM, either divided by body mass index (BMI) or squared height, and the absolute ASM were used as muscle mass indices. The risk of incident prediabetes and T2DM was assessed according to tertiles of these indices using a logistic regression model.

RESULTS

After a mean follow-up duration of 3.3 years, the highest ASM/BMI tertile group had a 61% lower risk of incident prediabetes and T2DM compared to the lowest tertile group, and this remained significant after we adjusted for covariates (adjusted odds ratio, 0.37; 95% confidence interval [CI], 0.15 to 0.92; P=0.032). Equivalent findings were observed in normal weight women (BMI <23 kg/m2), but this association was not significant for overweight women (BMI ≥23 kg/m2). Absolute ASM or ASM/height2 was not associated with the risk of postpartum T2DM.

CONCLUSION

A higher muscle mass, as defined by the ASM/BMI index, was associated with a lower risk of postpartum prediabetes and T2DM in Korean women with GDM.

Effect of serotonin on the cell viability of the bovine mammary alveolar cell-T (MAC-T) cell line

5-Hydroxytryptamine (5-HT), a monoamine, as a local regulator in the mammary gland is a chemical signal produced by the mammary epithelium cell. In cows, studies have shown that 5-HT is associated with epithelial cell apoptosis during the degenerative phase of the mammary gland. However, studies in other tissues have shown that 5-HT can effectively promote cell viability. Whether 5-HT could have an effect on mammary cell viability in dairy cows is still unknown. The purpose of this study was to determine: (1) effect of 5-HT on the viability of bovine mammary epithelial cells and its related signaling pathways, (2) interaction between prolactin (PRL) and 5-HT on the cell viability. The bovine mammary alveolar cell-T (MAC-T) were cultured with different concentrations of 5-HT for 12, 24, 48 or 72 hours, and then were assayed using cell counting kit-8, polymerase chain reaction (PCR) and immunobloting. The results suggested that 20 μM 5-HT treatment for 12 or 24 h promote cell viability, which was mainly induced by the activation of 5-HT receptor (5-HTR) 1B and 4, because the increase caused by 5-HT vanished when 5-HTR 1B and 4 was blocked by SB224289 and SB204070. And protein expression of mammalian target of rapamycin (mTOR), eukaryotic translation elongation factor 2 (eEF2), janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5) were decreased after blocking 5-HT 1B and 4 receptors. When MAC-T cells were treated with 5-HT and PRL simultaneously for 24 h, both the cell viability and the level of mTOR protein were significantly higher than that cultured with 5-HT or PRL alone. In conclusion, our study suggested that 5-HT promotes the viability of MAC-T cells by 5-HTR 1B and/or 4. Furthermore, there is a reciprocal relationship between PRL and 5-HT.

Breastfeeding mobile application for mothers with gestational diabetes mellitus: designed by mothers and experts

BACKGROUND

Mothers and babies with gestational diabetes have an increased risk of diabetes, obesity, and cardiovascular complications. Breastfeeding is known to help reduce complications in mothers and babies with gestational diabetes. However, the rate of breastfeeding among mothers with gestational diabetes is still low due to various barriers. Therefore, the purpose of this study was to develop a mobile application to improve the breastfeeding barrier of pregnant women with gestational diabetes.

METHODS

The Method of App Selection based on Users' Needs is a method used in designing app structure and user interface by considering user needs. This method was used to develop the Breastfeeding for Gestational Diabetes Mellitus App, reflecting the needs of target users. Four personas were created based on the experiences of four mothers with gestational diabetes mellitus, and these personas' needs were assessed and prioritized. Two professors and a clinical instructor in women's health nursing conducted an expert review and revised the contents.

RESULTS

Our "Breastfeeding for Gestational Diabetes Mellitus App" included the following components to promote breastfeeding in mothers with gestational diabetes mellitus: baby growth, breastfeeding records, information about mothers with gestational diabetes mellitus, information about breastfeeding, videos demonstrating breastfeeding methods and breast massage techniques, breastfeeding success stories, a message board, a section for frequently asked questions and answers, and links to breastfeeding education centers.

CONCLUSIONS

Use of our App is expected to help prevent complications in mothers with diabetes mellitus and their babies and to promote maternal and child health through improved breastfeeding practices, especially in social distancing situations resulting from COVID-19.

The adaptation of maternal energy metabolism to lactation and its underlying mechanisms

Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.

Modulatory role of prolactin in type 1 diabetes

Objectives

Patients with type 1 diabetes mellitus have been reported to have elevated prolactin levels and a possible relationship between prolactin levels and the development of the disease has been proposed. However, some studies show that prolactin mediates beneficial functions in beta cells. Therefore, we review information on the roles of prolactin in type 1 diabetes mellitus.

Content

Here we summarize the functions of prolactin in the immune system and in pancreatic beta cells, in addition, we describe studies related to PRL levels, its regulation and alterations of secretion in patients with type 1 diabetes mellitus.

Summary

Studies in murine models have shown that prolactin protects beta cells from apoptosis, stimulates their proliferation and promotes pancreatic islet revascularization. In addition, some studies in patients with type 1 diabetes mellitus have shown that elevated prolactin levels correlate with better disease control.

Outlook

Prolactin treatment appears to be a promising strategy to improve beta-cell vascularization and proliferation in transplantation and immunotherapies.

The role of mitochondria and mitochondrial hormone receptors on the bioenergetic adaptations to lactation

The most recognized role of mitochondria is producing more than 90% of the total cellular energy in the form of ATP. In addition, mitochondrial function encompasses the maintenance of antioxidant balance, the regulation of intracellular calcium concentrations, the progression of cell death, and the biosynthesis of purines, hemes, lipids, amino acids and steroid hormones. Mitochondria are also important hormone targets. Estrogens, progestagens, and prolactin, are among the hormones that can impact mitochondrial function and modulate the underlying adaptations to changing bioenergetic and metabolic needs. Lactation represents a metabolic challenge with significant increases in energy requirements and fluctuating levels of hormones. To meet these bioenergetic demands, liver mitochondria increase their state 3 and 4 respiration, adjust superoxide dismutase activity, and elevate succinate dehydrogenase-related respiration. Skeletal muscle mitochondria respond by increasing their respiratory control ratio and adjusting catalase activity. In this review, these adaptations are described considering the lactation hormonal milieu.

Serotonin in the regulation of systemic energy metabolism

Serotonin is a well‐known neurotransmitter that is synthesized from the amino acid, tryptophan. To date, more than 14 different serotonin receptors have been discovered; they exist universally in our body and enable diverse biological functions in different organs. Central serotonin regulates mood and behavior, and impacts the systemic energy balance by decreasing appetite. A number of drugs that modulate central serotonin function (e.g., fenfluramine, sibutramine and lorcaserin) were approved and used as anti‐obesity drugs, but then later withdrawn due to adverse cardiovascular and carcinogenic effects. Over the past decade, the role of peripheral serotonin in regulating systemic energy metabolism has been extensively explored using tissue‐specific knockout animal models. By inhibiting the action of serotonin in liver and adipose tissues, hepatic steatosis was improved and lipid accumulation was mitigated, respectively. Recent findings show that modulation of the serotonergic system is a promising therapeutic target for metabolic diseases. This review summarizes the role of serotonin in regulating energy metabolism in different organs, and discusses the potential of serotonin modulation for treating metabolic diseases.

Human Breast Milk: From Food to Active Immune Response With Disease Protection in Infants and Mothers

Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary. This review summarizes the current literature on the relationship between mother and her infant through breast milk with regard to disease protection. We will shed some light on the mechanisms underlying the roles of breast milk components in the maintenance of health of both child and mother.

The Impact of Intestinal Microorganisms and Their Metabolites on Type 1 Diabetes Mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disease with a complex etiology comprising numerous genetic and environmental factors; however, many of the mechanisms underlying disease development remain unclear. Nevertheless, a critical role has recently been assigned to intestinal microorganisms in T1DM disease pathogenesis. In particular, a decrease in intestinal microbial diversity, increase in intestinal permeability, and the translocation of intestinal bacteria to the pancreas have been reported in patients and animal models with T1DM. Moreover, intestinal microbial metabolites differ between healthy individuals and patients with T1DM. Specifically, short-chain fatty acid (SCFA) production, which contributes to intestinal barrier integrity and immune response regulation, is significantly reduced in patients with T1DM. Considering this correlation between intestinal microorganisms and T1DM, many studies have investigated the potential of intestinal microbiota in preventive and therapeutic strategies for T1DM.

OBJECTIVE

The aim of this review is to provide further support for the notion that intestinal microbiota contributes to the regulation of T1DM occurrence and development. In particular, this article reviews the involvement of the intestinal microbiota and the associated metabolites in T1DM pathogenesis, as well as recent studies on the involvement of the intestinal microbiota in T1DM prevention and treatment.

CONCLUSION

Intestinal microbes and their metabolites contribute to T1DM occurrence and development and may become a potential target for novel therapeutics.

Gestational Diabetes Mellitus: Diagnostic Approaches and Maternal-Offspring Complications

Gestational diabetes mellitus (GDM) is the most common complication during pregnancy and is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. GDM is associated with adverse pregnancy outcomes and long-term offspring and maternal complications. For GDM screening and diagnosis, a two-step approach (1-hour 50 g glucose challenge test followed by 3-hour 100 g oral glucose tolerance test) has been widely used. After the Hyperglycemia and Adverse Pregnancy Outcome study implemented a 75 g oral glucose tolerance test in all pregnant women, a one-step approach was recommended as an option for the diagnosis of GDM after 2010. The one-step approach has more than doubled the incidence of GDM, but its clinical benefit in reducing adverse pregnancy outcomes remains controversial. Long-term complications of mothers with GDM include type 2 diabetes mellitus and cardiovascular disease, and complications of their offspring include childhood obesity and glucose intolerance. The diagnostic criteria of GDM should properly classify women at risk for adverse pregnancy outcomes and long-term complications. The present review summarizes the strengths and weaknesses of the one-step and two-step approaches for the diagnosis of GDM based on recent randomized controlled trials and observational studies. We also describe the long-term maternal and offspring complications of GDM.

Insulin in the saliva of pigs: Validation of an automated assay and changes at different physiological conditions

This study aimed to evaluate whether insulin could be measured in the saliva of pigs and if its concentration changes in some physiological conditions. For this purpose, a validation of an automated heterologous immunoassay for measuring insulin in the saliva of pigs was performed. In addition, the possible changes of salivary insulin concentration in sows after food intake and during gestation and lactation were studied. The evaluated immunoassay was able to detect insulin in the saliva of pigs in a precise and accurate way when species-specific calibrators were used. There was no correlation in insulin concentrations between serum and saliva. Insulin concentrations showed a significant increase in the saliva of sows after feeding. Sows at farrowing and lactation presented higher salivary insulin levels as compared with those in gestation. In conclusion, the results showed that insulin could be measured in the saliva of pigs, and changes in its concentration can be detected due to food intake and different physiological conditions.

Role of serotonin in body weight, insulin secretion and glycaemic control

Obesity and type 2 diabetes are key healthcare challenges of the 21st century. Subsequent to its discovery in 1948, serotonin (5-hydroxytryptamine; 5-HT) has emerged as a principal modulator of energy homeostasis and body weight, prompting it to be a target of weight loss medications (eg, fenfluramine, D-fenfluramine, fenfluramine-phentermine and sibutramine). The potential risk of off-target effects led to these medications being withdrawn from clinical use and spurred drug discovery into 5-HT receptor selective ligands. The serotonin 2C receptor (5-HT2C R) is the primary receptor through which 5-HT impacts feeding and body weight and 5-HT2C R agonist lorcaserin was released for obesity treatment in 2012. Obese patients with type 2 diabetes prescribed medications that produce weight loss commonly observe improvements in type 2 diabetes. However, recent research has provided compelling evidence that 5-HT2C R agonists produce effects on blood glucose and insulin sensitivity independent of weight loss. As such, neuroactive 5-HT2C R agonists are a potential new category of type 2 diabetes medications. 5-HT is also expressed within pancreatic β cells, is co-released with insulin and may have a role in modulating insulin secretion. This review highlights the latest advances in the function of 5-HT in body weight, insulin release and glycaemic control.

A Systems Biology Approach to Investigating the Interaction between Serotonin Synthesis by Tryptophan Hydroxylase and the Metabolic Homeostasis

Obesity has become a global public health and economic problem. Obesity is a major risk factor for a number of complications, such as type 2 diabetes, cardiovascular disease, fatty liver disease, and cancer. Serotonin (5-hydroxytryptamine [5-HT]) is a biogenic monoamine that plays various roles in metabolic homeostasis. It is well known that central 5-HT regulates appetite and mood. Several 5-HT receptor agonists and selective serotonin receptor uptake inhibitors (SSRIs) have shown beneficial effects on appetite and mood control in clinics. Although several genetic polymorphisms related to 5-HT synthesis and its receptors are strongly associated with obesity, there is little evidence of the role of peripheral 5-HT in human metabolism. In this study, we performed a systemic analysis of transcriptome data from the Genotype-Tissue Expression (GTEX) database. We investigated the expression of 5-HT and tryptophan hydroxylase (TPH), the rate-limiting enzyme of 5-HT biosynthesis, in the human brain and peripheral tissues. We also performed differential gene expression analysis and predicted changes in metabolites by comparing gene expressions of tissues with high TPH expression to the gene expressions of tissues with low TPH expression. Our analyses provide strong evidence that serotonin plays an important role in the regulation of metabolic homeostasis in humans.

The short isoform of PRLR suppresses the pentose phosphate pathway and nucleotide synthesis through the NEK9-Hippo axis in pancreatic cancer

Prolactin binding to the prolactin receptor exerts pleiotropic biological effects in vertebrates. The prolactin receptor (PRLR) has multiple isoforms due to alternative splicing. The biological roles and related signaling of the long isoform (PRLR-LF) have been fully elucidated. However, little is known about the short isoform (PRLR-SF), particularly in cancer development and metabolic reprogramming, a core hallmark of cancer. Here, we reveal the role and underlying mechanism of PRLR-SF in pancreatic ductal adenocarcinoma (PDAC). Methods: A human PDAC tissue array was used to investigate the clinical relevance of PRLR in PDAC. The in vivo implications of PRLR-SF in PDAC were examined in a subcutaneous xenograft model and an orthotopic xenograft model. Immunohistochemistry was performed on tumor tissue obtained from genetically engineered KPC (KrasG12D/+; Trp53R172H/+; Pdx1-Cre) mice with spontaneous tumors. 13C-labeled metabolite measures, LC-MS, EdU incorporation assays and seahorse analyses were used to identify the effects of PRLR-SF on the pentose phosphate pathway and glycolysis. We identified the molecular mechanisms by immunofluorescence, coimmunoprecipitation, proximity ligation assays, chromatin immunoprecipitation and promoter luciferase activity. Public databases (TCGA, GEO and GTEx) were used to analyze the expression and survival correlations of the related genes. Results: We demonstrated that PRLR-SF is predominantly expressed in spontaneously forming pancreatic tumors of genetically engineered KPC mice and human PDAC cell lines. PRLR-SF inhibits the proliferation of PDAC cells (AsPC-1 and BxPC-3) in vitro and tumor growth in vivo. We showed that PRLR-SF reduces the expression of genes in the pentose phosphate pathway (PPP) and nucleotide biosynthesis by activating Hippo signaling. TEAD1, a downstream transcription factor of Hippo signaling, directly regulates the expression of G6PD and TKT, which are PPP rate-limiting enzymes. Moreover, NEK9 directly interacts with PRLR-SF and is the intermediator between PRLR and the Hippo pathway. The PRLR expression level is negatively correlated with overall survival and TNM stage in PDAC patients. Additionally, pregnancy and lactation increase the ratio of PRLR-SF:PRLR-LF in the pancreas of wild-type mice and subcutaneous PDAC xenograft tumors. Conclusion: Our characterization of the relationship between PRLR-SF signaling, the NEK9-Hippo pathway, PPP and nucleotide synthesis explains a mechanism for the correlation between PRLR-SF and metabolic reprogramming in PDAC progression. Strategies to alter this pathway might be developed for the treatment or prevention of pancreatic cancer.