The Rese Journal · Peptides

What each peptide on our shelf actually does

“Peptide” gets used like it means one thing. It doesn’t. A plain-English breakdown of what each one on our shelf does — and how a provider decides which fits you.

Gary A. Smith, MD, MMM, DABFMChairman & Chief Medical Officer — board-certified family physician, 25+ years

August 17, 2026

Every week I see a version of the same question: "I've been reading about peptides — which one should I take?" The question is reasonable. The word "peptide" has started appearing everywhere, attached to a long list of claims that range from legitimate to completely unsupported.

The honest answer is: it depends on what you're actually treating. "Peptide" is a category — short chains of amino acids that act as biological signals. What they signal, and where, varies enormously by molecule. Here's what each one on our shelf does, and how a provider thinks about whether it fits a specific patient.

What a peptide actually is

Your body makes peptides constantly. Hormones like insulin and glucagon are peptides. The GLP-1 your gut releases after a meal is a peptide. In clinical peptide therapy, we use either synthetic versions of peptides your body already makes, or molecules that interact with those same signaling pathways. The ones we prescribe at Rese work through your own biology — we're amplifying or supporting signals that are already there, not replacing them wholesale.

This matters because it shapes the risk profile. Peptides that work through your own hormone-release pathways carry a meaningfully different risk profile than anabolic hormones given directly. But "it's a peptide" doesn't make something automatically safe — mechanism matters, and so does clinical oversight.

Sleep and recovery: Sermorelin and Tesamorelin

Both are growth-hormone-releasing hormone (GHRH) analogues — they signal the pituitary gland to release more of your own growth hormone rather than introducing exogenous HGH. Growth hormone plays a significant role in overnight tissue repair, lean-mass maintenance, and the quality of deep sleep. As we age, growth-hormone output declines; these peptides support the pathway rather than bypassing it.

Sermorelin is the gentler starting point and is particularly well-studied for sleep quality and overnight recovery in the context of age-related GH decline. Tesamorelin is clinically studied in more targeted applications and tends to be selected when the picture includes body-composition goals alongside recovery. Your provider chooses between them based on your history, not on which is "stronger."

Cellular energy: NAD+ and Glutathione

NAD+ (nicotinamide adenine dinucleotide) isn't technically a peptide — it's a coenzyme. But it travels in the same clinical conversation because providers often consider it alongside peptide protocols for patients dealing with the kind of fatigue that sleep alone doesn't resolve. NAD+ is the molecule your cells use to produce energy through cellular respiration. Levels decline with age and are depleted by chronic stress, illness, and alcohol. Restoring them supports energy production at the cellular level rather than masking fatigue with stimulants.

We offer it as a nasal spray (gentler, good for steady daily support) and as a higher-dose injectable for patients who need more meaningful intervention. Glutathione is the body's primary antioxidant — produced internally but often depleted by the same factors that lower NAD+. An injectable protocol supports cellular defense, liver function, and skin clarity. It's often recommended alongside other protocols rather than as a standalone.

PT-141: a different mechanism entirely

Most interventions for desire work on blood flow. PT-141 works on the brain's motivation circuitry — a fundamentally different target.

PT-141 (bremelanotide) is a melanocortin receptor agonist. It acts centrally, through the nervous system, on the pathways involved in motivation and desire rather than the vascular pathways targeted by most other options in this space. It's used on a provider-guided schedule — not daily — and it's appropriate for a specific set of patients. Your provider's job is to determine whether you're one of them, which requires knowing your full health picture.

Skin: GHK-Cu and tretinoin

GHK-Cu is a copper peptide that occurs naturally in the body and has been studied for its role in wound healing and collagen synthesis. As a topical cream, it supports skin repair and structural renewal. Tretinoin (in cream and gel forms) is a prescription retinoid — vitamin A derivative — that accelerates cell turnover and is one of the most well-studied topical agents for improving skin texture and clarity over time. We carry two strengths because the right one depends on your skin's tolerance.

How a provider decides what fits you

Matching a patient to a protocol isn't symptom-matching — it's not "you're tired, so here's NAD+." It starts with understanding the underlying state: how you sleep, what your energy curve looks like throughout the day, what your labs show, what you've tried before and how you responded. Some protocols can start from the assessment alone; others need bloodwork first.

The goal is a protocol your provider can explain to you completely — what each component does, why it's there, and what you should expect. If you're ever handed a protocol without that conversation, ask for it. You're entitled to understand your own treatment.

This article is for general education and isn't medical advice, diagnosis, or treatment. Every treatment decision at Rese is made by a licensed provider who has reviewed your individual health history. Individual results vary.