Sermorelin 10mg

Sermorelin (GHRH 1-29) is a synthetic 29-amino acid peptide with a molecular weight of 3,357.88 Da. It corresponds to the N-terminal segment of the endogenous 44-amino acid GHRH molecule and is considered the shortest fully functional fragment retaining full biological activity. [1] [2]

Key Features:

• Binding Potency: Equipotent to full-length GHRH(1-40) in stimulating GH secretion
• Pulsatility: Stimulates natural pulsatile GH release (unlike rhGH)
• Feedback: Regulated by somatostatin negative feedback
• Gene Transcription: Stimulates hGH mRNA transcription, increases pituitary reserve [3]

Regulatory Status:

• FDA: Approved 1990 (diagnostic) / 1997 (pediatric GHD) as Geref. Voluntarily discontinued 2008 — NOT for tolerability/efficacy reasons. [4]
• WADA: Prohibited (S2 — Peptide Hormones). [5]

Developer: EMD Serono, Inc. (formerly Serono Laboratories)

Pharmacokinetic Highlights:

• Half-Life: ~11–12 min
• Clearance: 2.4–2.8 L/min

Discovery and historical context. Sermorelin was developed in the 1980s following the structural elucidation of human GHRH by Roger Guillemin and colleagues. Subsequent fragment-truncation studies established that the N-terminal 29 amino acids contain the full receptor-binding and signal-transduction activity of the parent 44-amino-acid hormone, leading to commercial development of GRF(1-29)-NH₂ as a research and diagnostic tool. [1] [2] The peptide is biologically equipotent to full-length GHRH on a molar basis but is more economical to synthesize, which is why nearly all GHRH-pathway research published after 1985 uses sermorelin rather than the native 1-44 sequence. [6]

Research framework. Sermorelin is widely used as the canonical GHRH-receptor probe in studies of pituitary somatotroph physiology, GH/IGF-1 axis aging, and pulsatile neuroendocrine secretion. Because endogenous somatostatin remains in the loop, sermorelin produces a self-limiting pulsatile GH burst rather than the sustained supraphysiologic exposure produced by exogenous recombinant human GH (rhGH) — an important distinction for research models examining GH receptor desensitization, IGF-1 feedback, and counter-regulatory hormone responses. [3] Closely related GHRH-pathway research compounds include tesamorelin (a DPP-4-resistant 44-amino-acid GHRH analog), CJC-1295 (an albumin-binding GHRH analog with extended half-life), and ipamorelin (a complementary GHS-R1a-pathway peptide). [7]

1. Receptor Target — GHRH Receptor

Sermorelin binds specifically to the GHRH receptor (GHRHR) on somatotroph cells in the anterior pituitary gland. Despite being a 29-aa fragment, it is equipotent to full-length GHRH(1-40) in stimulating GH secretion. [1] [6]

2. Downstream Signaling Cascades

Upon binding to the GHRHR, Sermorelin activates multiple intracellular pathways:

• Gₛ/Adenylyl Cyclase → cAMP Pathway: Primary mechanism — receptor activation triggers Gₛα, stimulating adenylyl cyclase to produce cAMP as a second messenger [6]
• MAPK Pathway: GHRHR activation also stimulates the mitogen-activated protein kinase pathway [6]
• Ca²⁺ Signaling: Cascades raise intracellular calcium levels, facilitating vesicle fusion and exocytosis of growth hormone

The product supplied here is for research use only regardless of regulatory status of related formulations.

3. Dose-Response Characteristics

• Duration vs Peak: The duration of GH release is more dose-dependent than peak magnitude [6]
• Older Adults: A dose-ranging study in older men reported IGF-1 endpoints relative to young adults [7]
• In Vitro Sensitivity: Minimal active concentration in rat pituitary cultures: 0.4 × 10⁻¹⁵ M [8]

4. Receptor Selectivity

In vitro: Does NOT stimulate LH, FSH, or Prolactin release (high somatotroph selectivity). [8]

In vivo (human): Minor acute rises in prolactin, FSH, and LH reported in children — effect not seen with GHRH(1-40) — suggesting slight differences between fragment and full-length. [9]

5. Cellular and Tissue-Level Effects

Anti-Tumor (Glioma):

• Blocks cell cycle progression in recurrent glioma cells
• Negatively regulates immune checkpoints, downregulates GHRHR/GGF
• Identified as most effective candidate from 4,865 drugs (P<0.0001) [1]

Immune Activation:

• Increases B cell number (~30%) and responsiveness to mitogens (+50%)
• Increases lymphocytes expressing IL-2 receptors (+70%)
• Enhances T cell responsiveness to phytohemagglutinin (+50%) [11]

6. Comparison to Related Compounds

7. Pharmacokinetics

👶 Pediatric GHD (Formerly FDA-registered)

Sermorelin (as Geref) was studied in the Geref International Study Group multicenter trial (n=110) in pediatric GH deficiency, with growth-velocity endpoints reported. That former registration does not apply to this research-grade material. Published literature is listed under References. [2]

🔬 Diagnostic Evaluation

Sermorelin has been used in the literature as a provocative test of pituitary GH reserve, distinguishing hypothalamic vs pituitary causes of GHD. Fewer false positives compared to other provocative tests. [2]

🧓 Aging Biology / Age-Related GH Decline

GH secretion has been studied in older adults. A dose-ranging study in men aged 60–78 reported IGF-1 levels relative to young adults. [7] [12]

🧠 Cognitive Function & Sleep

Slow-wave sleep, which is correlated with nocturnal GH secretion, has been examined as an endpoint in GHRH research on age-related changes in the somatotropic axis. [13]

🛡️ Immunosenescence

In aging adults, B-cell, T-cell-responsiveness, IL-2-receptor and immunoglobulin endpoints were reported. [11]

💪 Body Composition / Hypogonadal Men

A retrospective study (n=14) of hypogonadal men on testosterone + Sermorelin/GHRP-2/GHRP-6 reported IGF-1 endpoints at 90, 180, and 270 days. Lean body mass and visceral fat endpoints were also reported. [14]

🎯 Oncology — Glioma

Bioinformatics screening of 4,865 drugs identified Sermorelin as the most effective candidate for recurrent glioma (P<0.0001). In vitro, it inhibited U87/LN229 cell growth dose-dependently by blocking cell cycle and negatively regulating immune checkpoints. [1]

GHRH-Receptor Pulsatility and Somatostatin-Feedback Profiling

Sermorelin is used as a research tool to investigate whether stimulating endogenous, pulsatile GH secretion through the GHRH receptor preserves the natural somatostatin negative-feedback loop and yields a different IGF-1 and metabolic-substrate signature compared to continuous exogenous recombinant human GH. Comparative ultradian profiling studies in young versus elderly cohorts have catalogued amplitude, frequency, and trough patterns useful for modelling natural-pulsatility versus tonic-elevation GH biology. [7]

Comparative Research Context

Within the GHRH-axis research family, sermorelin is most directly compared with tesamorelin (full-length GHRH(1-44) with N-terminal acylation for DPP-4 resistance), CJC-1295 (long-acting GHRH analog), and the lipolytic hGH-fragment AOD-9604. These cross-comparisons inform research designs investigating whether truncated GHRH(1-29), full-length GHRH(1-44), or albumin-binding long-acting GHRH analogs produce distinct downstream IGF-1 and substrate-handling phenotypes.

Clinical Studies

Handling Safety

Handle with standard laboratory PPE. Consult the SDS.

Regulatory note: FDA confirmed Geref was NOT withdrawn for tolerability or efficacy reasons. [4]