Biology of Incretins: GLP-1 and GIP

A neurotrophic model for stress-related mood disorders.

Mechanisms and functional implications of adult neurogenesis.

Molecular subclasses of high-grade glioma predict prognosis, delineate a pattern of disease progression, and resemble stages in neurogenesis

Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in ...

The Physiology of Glucagon-like Peptide 1

Glucagon-like peptide-1 (GLP-1) is a gut peptide that, together with its receptor, GLP-1R, is expressed in the brain. Here we show that intracerebroventricular (i.c.v.) GLP-1 and [Ser(2)]exendin(1-9) (HSEGTFTSD; homologous to a conserved domain in the glucagon/GLP-1 family) enhance associative and spatial learning through GLP-1R. [Ser(2)]exendin(1-9), but not GLP-1, is also active when administered peripherally. GLP-1R-deficient mice have a phenotype characterized by a learning deficit that is restored after hippocampal Glp1r gene transfer. In addition, rats overexpressing GLP-1R in the hippocampus show improved learning and memory. GLP-1R-deficient mice also have enhanced seizure severity and neuronal injury after kainate administration, with an intermediate phenotype in heterozygotes and phenotypic correction after Glp1r gene transfer in hippocampal somatic cells. Systemic administration of [Ser(2)]exendin(1-9) in wild-type animals prevents kainate-induced apoptosis of hippocampal neurons. Brain GLP-1R represents a promising new target for both cognitive-enhancing and neuroprotective agents.

Glucagon-like peptide-1 receptor is involved in learning and neuroprotection

An enriched environment is associated with hippocampal plasticity, including improved cognitive performance and increased neurogenesis. Here, we show that hippocampal expression of vascular endothelial growth factor (VEGF) is increased by both an enriched environment and performance in a spatial maze. Hippocampal gene transfer of VEGF in adult rats resulted in approximately 2 times more neurogenesis associated with improved cognition. In contrast, overexpression of placental growth factor, which signals through Flt1 but not kinase insert domain protein receptors (KDRs), had negative effects on neurogenesis and inhibited learning, although it similarly increased endothelial cell proliferation. Expression of a dominant-negative mutant KDR inhibited basal neurogenesis and impaired learning. Coexpression of mutant KDR antagonized VEGF-enhanced neurogenesis and learning without inhibiting endothelial cell proliferation. Furthermore, inhibition of VEGF expression by RNA interference completely blocked the environmental induction of neurogenesis. These data support a model in which VEGF, acting through KDR, mediates the effect of the environment on neurogenesis and cognition.

Xiangyang Jiao

Papers

Glucagon-like peptide-1 receptor is involved in learning and neuroprotection

VEGF links hippocampal activity with neurogenesis, learning and memory.