GLP-1s & Novel Peptides in Obesity, Diabetes & Metabolic Health | Katrin Svensson | Episode 298

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Endogenous peptide diversity, GLP-1 drugs, and methods for novel peptide discovery.

TOPICS DISCUSSED:

• Peptide Structure & Production: Short amino acid chains (3-50 residues) cleaved from larger precursors by PCSK enzymes, stored in dense-core vesicles, and released upon stimuli rather than acting as folded enzymes like proteins.
• Tissue-Specific Processing: The same precursor yields different peptides by tissue; preproglucagon produces glucagon in pancreas but GLP-1 in gut L-cells due to distinct cleavage patterns.
• Signaling Timescales: Peptides act over minutes via GPCRs and can drive longer transcriptional changes such as FOS expression, yet are cleared rapidly by proteases and kidneys.
• Endogenous GLP-1: Meal-stimulated incretin from gut that boosts insulin secretion with a half-life of only minutes, limiting primary action to periphery rather than deep brain structures.
• GLP-1 Engineering for Brain Access: DPP4 site mutations plus lipid conjugation enable albumin binding, extend half-life, and raise brain exposure.
• Dose-Dependent Effects: Low GLP-1 doses mainly lower blood glucose via pancreas; higher doses engage hindbrain and hypothalamic neurons to suppress appetite and alter food preference.
• Novel Peptide Discovery: Computational scans across the genome flag hundreds of uncharacterized precursors, facilitating new peptide discovery.
• BRP Peptide: This newly discovered brain-derived peptide suppresses feeding in GLP-1 receptor knockout mice, activates non-overlapping neurons, and does not slow gastric emptying.

ABOUT THE GUEST: Katrin Svensson, PhD, is a biochemist and physiologist who leads a laboratory at Stanford University focused on peptide hormone physiology and the regulation of energy balance.

PRACTICAL TAKEAWAYS:

• GLP-1 drugs require higher doses to engage brain satiety circuits for meaningful weight loss; lower doses primarily improve glucose control with little effect on appetite.
• Response varies widely across individuals, with some losing over 25% body weight while others see minimal change.
• Emerging peptides under study may suppress appetite via brain pathways that avoid the gastric slowing responsible for common GI side effects of current GLP-1 drugs.
• Research peptides purchased online frequently show variable purity below pharmaceutical standards and may contain unsafe formulation components or aggregates.

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