OBJECTIVE:Optimal weight loss involves decreasing adipose tissue while preserving lean muscle mass. Identifying molecular mediators that preserve lean muscle mass is therefore a clinically important goal. We have shown that circulating, postprandial FGF19 levels are lower in patients with obesity and decrease further with comorbidities such as type 2 diabetes and MASLD. Preclinical studies have shown that FGF15 (mouse ortholog of human FGF19) is necessary to protect against lean muscle mass loss following metabolic surgery-induced weight loss in a mouse model of diet-induced obesity. We evaluated if non-surgical weight loss interventions also lead to increased systemic levels of FGF19 and whether FGF19 levels are predictive of lean muscle mass following rapid weight loss in human subjects with obesity. RESEARCH DESIGN AND METHODS:Weight loss was induced in 176 subjects with obesity via a very low-energy diet, VLED (800 kcal/d) in the form of total liquid meal replacement for 3-4 months. We measured plasma FGF19 levels at baseline and following VLED-induced weight loss. Multiple linear regression was performed to assess if FGF19 levels were predictive of lean mass at baseline (obesity) and following VLED. RESULTS:Postprandial levels of FGF19 increased significantly following VLED-weight loss. Multiple linear regression analysis showed that baseline (obesity) FGF19 levels, but not post VLED FGF19 levels, significantly predicted the percent of lean muscle mass after VLED-induced weight loss, while controlling for age, sex, and the baseline percent lean mass. CONCLUSION:These data identify gut-muscle communication and FGF19 as a potentially important mediator of the preservation of lean muscle mass during rapid weight loss.

Avoidance or anxiety-like behavior is accompanied by corresponding changes in hypothalamic-pituitary-adrenal (HPA) axis activation. The underlying neural circuitry for this coordinated behavioral and neuroendocrine control is not well established. Prior studies pointed to a neural projection from the ventral subiculum (vSub) to the bed nucleus of the stria terminalis (BNST) that can inhibit the HPA axis response to stress. Here, we used chemogenetics to investigate the role of vSub neurons and their projection to the anterior BNST (aBNST) in avoidance behavior and the accompanying corticosterone response in male and female mice. Surprisingly, we found that chemogenetic activation of ventral subiculum neurons increased the HPA axis response to an open field test in male and female mice, which was also seen with selective activation of vSub neurons projecting to the anterior BNST (vSub-aBNST neurons). On the other hand, VSub neuron and vSub-aBNST neuron activation had different effects on avoidance behavior, suggesting that the behavioral role of the VSub is variable and is dissociable from its neuroendocrine effects. In conclusion, our results reveal a surprising and novel role for the ventral subiculum in HPA axis activation via the anterior BNST. We also show that, like the ventral hippocampus, ventral subiculum neurons can increase or decrease avoidance behavior depending on their downstream projection.

Young Black males (YBM) ages 18 to 24 years are more at risk of contracting sexually transmitted infections (STIs) and have a substantially greater need for sexual reproductive health (SRH) services than other groups. Despite this significant need, the extant literature does not provide a comprehensive picture of how YBM seek preventive care services (e.g., STI testing). Therefore, the purpose of this review is to address YBM’s SRH access and use of STI/HIV testing and screening in this population, with a specific emphasis on young heterosexual Black males, by identifying barriers and facilitators of engaging with SRH care. An electronic search was performed using Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycInfo, PubMed, and Scopus online databases. Keywords were adapted to each database and included variations of “Black males,” “sexual reproductive healthcare services,” “youth (18-24 years old),” and “healthcare access and utilization.” Studies from the review reported that barriers to engaging in SRH care included lack of health insurance, ideas of masculinity that conflict with SRH care, stigma related to accessing services, and lack of knowledge regarding available services and care options. The top facilitators for utilizing SRH care were engagement on behalf of health clinics, confidence gained from social support, access to quality health care in one’s community, and trust in the health care system and providers. This review contributes to the current state of the science and is important to the improvement of high-quality services for this population, including respect, choice in care, confidentially, and compassion.