Mind & Matter

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Blood-brain barrier as a dynamic interface allowing selective passage of nutrients, peptides, and gut hormones.
TOPICS DISCUSSED:
Blood-Brain Barrier Structure: Capillary endothelial cells with tight junctions, absent fenestrae, and minimal vesicles create a selective interface; supported by astrocytes and pericytes.
Crossing Mechanisms: Lipid-soluble small molecules diffuse passively; glucose, amino acids, and regulatory peptides use saturable transporters whose rates vary by need.
Peptide Transport: Many peptides cross via lipid solubility or specific transporters; rate, not all-or-none presence, determines biological relevance; efflux systems remove some (e.g. certain enkephalins).
Dynamic Regulation: Transporters for leptin and insulin are modulated by epinephrine, triglycerides, and brain demand; changes occur in aging and Alzheimer’s (reduced glucose uptake, impaired Aβ efflux).
Circumventricular Organs: Leaky capillary regions allow rapid sampling of blood signals while tanycytes limit spread to surrounding brain tissue.
Drug Delivery Challenges: Small lipid-soluble drugs, barrier disruption (e.g. focused ultrasound), and “Trojan-horse” strategies each have limitations; intranasal delivery shows rapid brain distribution.
Peptides & Brain Effects: Gut peptides like GLP-1 analogs, insulin, and ghrelin influence cognition and memory; brain entry predicts central effects.
GUEST: William Banks, MD is a physician-scientist and leading researcher on the blood-brain barrier. He has focused on humoral brain-body communication, peptide transport, and the barrier’s role in health and disease.
RELATED CONTENT:
M&M 298 | GLP-1s & Novel Peptides in Obesity, Diabetes & Metabolic Health | Katrin Svensson
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Ferroptosis, an iron-dependent cell death pathway driven by lipid peroxidation; chronoferoptosis, in which chronic stress sensitizes neurons gradually.
TOPICS DISCUSSED:
Cell Death Pathways: Apoptosis proceeds through regulated steps with surface “eat me” signals that enable non-inflammatory clearance by phagocytes, whereas ferroptosis and related pathways release cellular contents that can amplify local damage and inflammation.
Ferroptosis Discovery: Work on glutamate toxicity in neuronal cell lines first identified a glutathione-depletion pathway termed oxytosis; parallel studies in cancer cells renamed and generalized it as ferroptosis to highlight iron’s catalytic role.
Lipid Peroxidation: Polyunsaturated fatty acids in membranes are oxidized non-enzymatically when ferrous iron reacts with hydrogen peroxide in the Fenton reaction, generating hydroxyl radicals that produce toxic lipid peroxides and reactive carbonyls that modify proteins.
GPX4 & Glutathione: Glutathione peroxidase-4 is an enzyme that reduces lipid peroxides within membranes and requires glutathione as cofactor; depletion of either component removes this critical line of defense.
Chronoferoptosis: Nine-day treatment of differentiated neuronal cells with chronic iron or glutathione synthesis inhibitor reduced GPX4 protein, raised basal lipid peroxidation, and increased cell death after addition of otherwise sublethal secondary stressors.
Protective Compounds: Screening identified flavonoids such as fisetin and sterubin plus synthetic molecules J-147 and CMS-121 that block lipid peroxidation directly or indirectly and, in several cases, also raise glutathione levels.
Human Disease Evidence: Postmortem brain tissue from Alzheimer’s and Parkinson’s patients shows elevated lipid peroxidation markers and altered iron handling in vulnerable regions; similar changes appear in animal models of multiple diseases.
Dietary & NRF2 Links: Compounds that activate the NRF2 transcription factor, including sulforaphane from broccoli and certain flavonoids, upregulate antioxidant enzymes including GPX4 and may support long-term cellular resilience.
ABOUT THE GUEST: Pamela Maher, PhD is a research professor at the Salk Institute for Biological Studies in La Jolla, California. Her laboratory studies ferroptosis mechanisms in neurodegenerative diseases and works to identify compounds that inhibit iron-dependent lipid peroxidation. 

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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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The possible role of deuterium (heavy isotope of hydrogen) in regulating cell division, mitochondrial metabolism & cancer.
TOPICS DISCUSSED:
Deuterium Basics: Deuterium is twice as massive as regular hydrogen; natural water contains ~150 ppm, with stronger oxygen-deuterium bonds slowing reactions compared to oxygen-hydrogen.
Mitochondrial Role: Healthy mitochondria produce deuterium-depleted metabolic water (~110 ppm from fat oxidation vs. ~150 ppm from carbs), helping maintain low cellular D:H ratios.
Cell Growth Regulation: Lower deuterium slows cell division in vitro; cells sense small D:H changes, with higher levels (near/above 150 ppm) promoting growth.
In Vitro Evidence: DDW (e.g., 25-125 ppm) can reduce proliferation and alters cancer-related gene expression.
Animal Models: DDW caused tumor regression in mice with transplanted human cancers and showed possible efficacy in veterinary use for dogs and cats.
Human Prostate Cancer: Phase 2 randomized study showed greater Prostate-Specific Antigen (PSA) reduction, tumor shrinkage, and better 1-year survival with DDW plus standard therapy vs. placebo.
Dietary Modulation: Ketogenic/high-fat diets lower body deuterium from lipid oxidation.
Broader Implications: Potential in neurodegeneration models; larger trials needed for registration as adjunct cancer therapy.
ABOUT THE GUEST: Gábor Somlyai, PhD is a molecular biologist who pioneered deuterium depletion studies at the National Institute of Oncology in Hungary. His primary work focuses on the role of deuterium in living organisms and the development of deuterium-depleted water for cancer therapy.
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Support the show
Support my work:
Good Chemistry: Personalized, science-based health consulting. Work with me directly.
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For all the ways you can support my efforts.