Glucagon-like Peptide 1 Receptors in Lateral Septum Affect Food Intake

• Other Authors: Terrill, Sarah J. (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Nanoscience
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-9261

Hindbrain glucagon-like peptide 1 (GLP-1) neurons project to numerous feeding-relevant forebrain areas. One such region is the lateral septum (LS), which plays a role in learning, motivation, and stress. We hypothesized that stimulation of GLP-1R in the LS affects food intake. Rats were implanted with unilateral cannulas targeting the LS, and intra-LS injections were made 30 min before dark cycle onset. We examined the effects of the GLP-1R agonist Exendin 4 (Ex4) at doses subthreshold for effect when delivered to the lateral ventricle (0.01 or 0.025 µg). Ex4 had no effect on feeding at 2 and 4 h into the dark phase, but the 0.025 µg dose suppressed overnight intake. We then assessed the effects of ventricle-subthreshold doses (1.0, 2.5, 5.0, or 10.0 µg) of the GLP-1R antagonist Exendin (9-39) (Ex9) vs vehicle injected into the LS. Ex9 increased chow intake at 2, 4, and 20 hours post-dark onset relative to vehicle. We assessed the role of LS GLP-1R in motivation for food by examining operant responding for sucrose on progressive ratio (PR) schedule. Intra-LS injections of Ex9 (10.0 µg) or vehicle were made 45 min prior to the start of the PR session. We also tested PR responding after a nutrient preload designed to maximize GLP-1 neuron activation. The preload strongly suppressed PR responding, but blockade of LS GLP-1R did not affect motivation for sucrose in either preload condition. The Ensure preload significantly suppressed 24-hour chow intake relative to no preload condition. However, intra-LS Ex9 treatment significantly reduced this compensatory reduction in chow intake after the preload. These experiments suggest that the LS is a relevant site for neuronal GLP-1 influence on food intake. === A Thesis submitted to the Department of Psychology in partial fulfillment of the requirements for the degree of Master of Science. === Fall Semester, 2014. === October 1, 2014. === Food Intake, GLP-1, Lateral Septum === Includes bibliographical references. === Diana Williams, Professor Directing Thesis; Alan Spector, Committee Member; Colleen Kelley, Committee Member.