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Although innate immunity is linked to metabolic health, the effect of leptin signaling in cells from the innate immune system on glucose homeostasis has not been thoroughly investigated. We generated two mouse models using Cre-lox methodology to determine the effect of myeloid cell-specific leptin receptor (Lepr) reconstitution and Lepr knockdown on in vivo glucose metabolism. Male mice with myeloid cell-specific Lepr reconstitution (Lyz2Cre + Lepr loxTB/loxTB ) had better glycemic control as they aged compared to male mice with whole-body transcriptional blockade of Lepr (Lyz2Cre - Lepr loxTB/loxTB ). In contrast, Lyz2Cre + Lepr loxTB/loxTB females only had a trend for diminished hyperglycemia after a prolonged fast. During glucose tolerance tests, Lyz2Cre + Lepr loxTB/loxTB males had a mildly improved plasma glucose profile compared to Cre - controls while Lyz2Cre + Lepr loxTB/loxTB females had a similar glucose excursion to their Cre - controls. Myeloid cell-specific Lepr knockdown (Lyz2Cre + Lepr flox/flox ) did not significantly alter body weight, blood glucose, insulin sensitivity, or glucose tolerance in males or females. Expression of the cytokine interleukin 10 (anti-inflammatory) tended to be higher in adipose tissue of male Lyz2Cre + Lepr loxTB/loxTB mice (p = 0.0774) while interleukin 6 (pro-inflammatory) was lower in male Lyz2Cre + Lepr flox/flox mice (p < 0.05) vs. their respective controls. In conclusion, reconstitution of Lepr in cells of myeloid lineage has beneficial effects on glucose metabolism in male mice., (© 2021. The Author(s).)

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide critical to the regulation of the stress response, including having a role in energy homeostasis. Mice lacking PACAP are cold-sensitive and have impaired adrenergic-induced thermogenesis. Interestingly, Pacap null mice can survive cold housing if acclimated slowly, similar to observations in uncoupling protein 1 (UCP1)-deficient mice. We hypothesized that Pacap null mice use alternate thermogenic pathways to compensate for impaired adaptive thermogenesis when acclimated to cold. Observations of behavior and assessment of fiber type in skeletal muscles did not show evidence of prolonged burst shivering or changes in oxidative metabolism in male or female Pacap -/- mice during cold acclimation compared with Pacap +/+ mice. Despite previous work that has established impaired capacity for adaptive thermogenesis in Pacap null mice, adaptive thermogenesis can be induced in mice lacking PACAP to support survival with cold housing. Interestingly, sex-specific morphological and molecular differences in adipose tissue remodeling were observed in Pacap null mice compared with controls. Thus, sexual dimorphisms are highlighted in adipose tissue remodeling and thermogenesis with cold acclimation in the absence of PACAP. NEW & NOTEWORTHY This manuscript adds to the literature of endocrine regulation of adaptive thermogenesis and energy balance. It specifically describes the role of pituitary adenylate cyclase-activating polypeptide on the regulation of brown adipose tissue via the sympathetic nervous system with a focus on compensatory mechanisms of thermogenesis. We highlight sex-specific differences in energy metabolism.

New Findings: What is the central question of this study? Can chronic treatment of pituitary adenylate cyclase-activating polypeptide (PACAP) deficient mice with the melanocortin agonist melanotan II during cold acclimation rescue the impaired thermogenic capacity previously observed in PACAP deficient mice? What is the main finding and its importance? Using a genetic model of PACAP deficiency, this study provides evidence that PACAP acts upstream of the melanocortin system in regulating sympathetic nerve activity to brown adipose tissue in mice., Abstract: Impaired adipose tissue function in obesity, including reduced thermogenic potential, has detrimental consequences for metabolic health. Hormonal regulation of adaptive thermogenesis is being explored as a potential therapeutic target for human obesity. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide expressed in nuclei of the hypothalamus known to regulate energy expenditure, and functional studies reveal a role for PACAP in the central regulation of thermogenesis, although mechanisms are not well understood. We hypothesized that PACAP acts upstream of the melanocortin system to regulate sympathetic nerve activity to stimulate thermogenesis. To assess this, female PACAP -/- and PACAP +/+ mice were given daily peripheral injections of a melanocortin receptor agonist, melanotan II (MTII), for 3 weeks during cold acclimation, and the effect of MTII on thermogenic capacity and adipose tissue remodelling was examined by physiological and histological analyses. MTII partially rescued the impaired thermogenic capacity in PACAP -/- mice as compared to PACAP +/+ mice as determined by measuring noradrenaline-induced metabolic rate. In addition, MTII treatment during cold acclimation corrected the previously identified deficit in lipid utilization in response to adrenergic stimulation in PACAP -/- null mice, suggesting impaired lipid mobilization may contribute to the impaired thermogenic capacity of PACAP -/- mice. Results presented here provide physiological evidence to suggest that PACAP acts upstream of melanocortin receptors to facilitate sympathetically induced mechanisms of adaptive thermogenesis in response to cold acclimation., (© 2020 The Authors. Experimental Physiology © 2020 The Physiological Society.)

The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Obesity arises from disrupted energy balance and is caused by chronically higher energy intake compared to expenditure via basal metabolic rate, exercise, and thermogenesis. The brown adipose tissue (BAT), the primary thermogenic organ, has received considerable attention as a potential therapeutic target due to its ability to burn lipids in the production of heat. Pituitary adenylate cyclase-activating polypeptide (PACAP) has been identified as a key regulator of the physiological stress response both centrally and peripherally. While PACAP has been shown to increase thermogenesis by acting at the hypothalamus to increase sympathetic output to BAT, a peripheral role for PACAP-activated thermogenesis has not been studied. We identified PACAP receptor (PAC1, VPAC1/2) expression for the first time in murine BAT and confirmed their expression in white adipose tissues. PAC1 receptor expression was significantly altered in all three adipose tissues studied in response to 3.5-week cold acclimation, with expression patterns differing by depot type. In primary cell culture, VPAC1 was increased in differentiated compared to non-differentiated brown adipocytes, and the same trend was observed for the PACAP-specific receptor PAC1 in gonadal white fat primary cultures. The primary PAC1R mRNA splice variant in interscapular BAT was determined as isoform 2 by RNA-Seq. These results show that PACAP receptors are present in adipose tissues and may have important functional roles in adipocyte differentiation, lipid metabolism, or adipose sensitization to sympathetic signaling in response to thermogenic stimuli.

Several gynecological problems are occasionally found at laparoscopy. These include pelvic endometriosis, pelvic adhesions, blocked fallopian tubes, tubal pregnancy, pelvic inflammatory disease, ovarian cysts, and uterine fibroids. Most can be handled endoscopically, with the laparoscope inserted through an umbilical incision, although an open laparotomy may sometimes be necessary.

Patients with different types of luteal phase defects were studied with the use of the radioimmunoassay for the beta subunit of human chorionic gonadotropin (hCG) to determine if unsuspected subclinical pregnancies were more common in a particular type of defect. A type I luteal phase defect is always characterized by a chronologic lag in endometrial development when repeatedly studied with timed endometrial biopsies. A type II luteal phase defect is always characterized by an in phase endometrium when repeatedly studied by timed endometrial biopsies but always has less than a 14 day luteal span. All blood samples were drawn at least 7 days after ovulation/conception. In 22 cycles in which patients had a type I luteal phase defect, no subclinical pregnancies were detected. In 18 cycles in which a type II luteal phase defect was present, 12 instances of unsuspected subclinical pregnancy were detected and all ended in spontaneous abortion. This study shows that unsuspected subclinical pregnancies ending in abortion do occur and are quite commonly associated with the type II luteal phase defect.