SUMMARY Glucagon-like peptide-1 (GLP-1), an insulinotropic peptide released from the intestine after eating, is essential for normal glucose tolerance (GT). To determine whether this effect is mediated directly by GLP-1 receptors (GLP1R) on islet β-cells, we developed mice with β-cell specific knockdown of Glp1r. β-cell Glp1r knockdown mice had impaired GT after intraperitoneal (IP) glucose, and did not secrete insulin in response to IP or intravenous GLP-1. However, they had normal GT after oral glucose, a response that was impaired by a GLP1R antagonist. β-cell Glp1r knockdown mice had blunted responses to a GLP1R agonist, but intact glucose lowering with a DPP-4 inhibitor. Thus, in mice, β-cell Glp1r are required to respond to hyperglycemia and exogenous GLP-1, but other factors compensate for reduced GLP-1 action on the β-cell during meal ingestion. These results support a role for extra-islet GLP1R in oral glucose tolerance and paracrine regulation of β-cells by islet GLP-1.

No abstract

Cataloguing gene expression during development of the genitourinary tract will increase our understanding not only of this process but also of congenital defects and disease affecting this organ system. We have developed a high-resolution ontology with which to describe the subcompartments of the developing murine genitourinary tract. This ontology incorporates what can be defined histologically and begins to encompass other structures and cell types already identified at the molecular level. The ontology is being used to annotate in situ hybridisation data generated as part of the Genitourinary Development Molecular Anatomy Project (GUDMAP), a publicly available data resource on gene and protein expression during genitourinary development. The GUDMAP ontology encompasses Theiler stage (TS) 17 to 27 of development as well as the sexually mature adult. It has been written as a partonomic, text-based, hierarchical ontology that, for the

Studies focused on end-points that are confounded by stress are best performed under minimally stressful conditions. The objective of this study was to demonstrate the impact of handling designed to reduce animal stress on measurements of glucose tolerance. A cohort of mice (CD1.C57BL/6) naïve to any specific handling were subjected to either a previously described “cup” handling method, or a “tail-picked” method in which the animals were picked up by the tail (as is common for metabolic studies). Following training, an elevated plus maze (EPM) test was performed followed by measurement of blood glucose and plasma corticosterone. A second cohort (CD1.C57BL/6) was rendered obese by exposure to a high fat diet, handled with either the tail-picked or cup method and subjected to an intraperitoneal glucose tolerance test. A third cohort of C57BL/6 mice was exposed to a cup regimen that included a component of massage and was subjected to tests of anxiety-like behavior, glucose homeostasis, and corticosterone secretion. We found that the cup mice showed reduced anxiety-like behaviors in the EPM coupled with a reduction in blood glucose levels compared to mice handled by the tail-picked method. Additionally, cup mice on the high fat diet exhibited improved glucose tolerance compared to tail-picked controls. Finally, we found that the cup/massage group showed lower glucose levels following an overnight fast, and decreased anxiety-like behaviors associated with lower stress-induced plasma corticosterone concentration compared to tail-picked controls. These data demonstrate that application of handling methods that reduce anxiety-like behaviors in mice mitigates the confounding contribution of stress to interpretation of metabolic endpoints (such as glucose tolerance).

No abstract