AOD9604

Research Overview

AOD9604 serves as a valuable research tool for investigating growth hormone fragment biology and selective metabolic effects dissociated from classical GH receptor-mediated actions. This synthetic peptide represents the C-terminal domain of human growth hormone (amino acids 176-191), a region identified with lipolytic and anti-lipogenic properties in early hGH research. Unlike full-length growth hormone, AOD9604 does not bind or activate the growth hormone receptor, enabling investigation of GH receptor-independent metabolic pathways.

The peptide’s development addresses research questions about functional domains within the hGH molecule and whether metabolic benefits can be separated from growth-promoting and insulin-antagonistic effects. Laboratory studies investigate AOD9604’s effects on adipocyte lipolysis, lipid metabolism enzymes, body composition changes, and metabolic signaling pathways. Research protocols examine these effects in adipocyte cell cultures, tissue explants, and preclinical animal models, with particular focus on mechanisms distinct from catecholamine-stimulated lipolysis.

AOD9604 research demonstrates the principle that peptide fragments can retain specific biological activities while losing others associated with the parent hormone. The peptide’s structure includes a tyrosine substitution at position 177 (replacing phenylalanine) which enhances stability and potency compared to the native hGH 176-191 sequence. This modification makes AOD9604 a more robust research tool for investigating C-terminal hGH fragment biology and selective lipolytic mechanisms.

Molecular Characteristics

Complete Specifications:

• Molecular Weight: 1,815.08 Da
• Molecular Formula: C₇₈H₁₂₃N₂₃O₂₆S₂
• Amino Acid Sequence: Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe
• Peptide Length: 16 amino acids
• Peptide Classification: hGH C-terminal fragment (176-191), modified with Tyr177
• Disulfide Bond: Cys7-Cys14 (corresponding to Cys182-Cys189 in hGH)
• Appearance: White to off-white lyophilized powder
• Solubility: Water, bacteriostatic water, phosphate buffered saline

The peptide’s 16-amino acid structure corresponds to the C-terminal region of human growth hormone with a single modification: tyrosine replaces phenylalanine at position 177 (position 1 in the fragment). This substitution enhances peptide stability and lipolytic potency. The sequence includes two cysteine residues that form a disulfide bond, creating a constrained loop structure important for biological activity. Unlike full-length hGH (191 amino acids, 22 kDa), this fragment lacks the receptor-binding domains and does not activate the growth hormone receptor, providing specificity for investigating receptor-independent effects.

Pharmacokinetic Profile in Research Models

AOD9604 pharmacokinetic characterization in preclinical research:

Absorption and Distribution:

• Subcutaneous bioavailability: Moderate (30-50% in rodent models)
• Rapid absorption from injection site
• Multiple administration routes investigated: SC, IV, IP
• No GH receptor binding or activation

Elimination:

• Plasma half-life: Short (<2 hours)
• Rapid clearance from circulation
• Proteolytic degradation by peptidases
• Renal clearance of fragments

Metabolic Effects:

• Tissue distribution: Preferential adipose tissue effects
• Duration of action: Extends beyond plasma presence (tissue retention)
• No effect on: IGF-1 levels, glucose homeostasis, linear growth
• Selective action: Lipolytic effects without GH receptor-mediated effects

These properties inform research protocol design, particularly regarding dosing frequency and timing of metabolic assessments.

Research Applications

Lipolysis Mechanism Investigation

AOD9604 serves as a research tool for investigating non-β-adrenergic lipolytic pathways:

• Hormone-Sensitive Lipase: Examination of HSL activation, phosphorylation status, and lipid droplet association
• ATGL Regulation: Research on adipose triglyceride lipase expression and activity modulation
• Perilipin Phosphorylation: Investigation of lipid droplet coating protein regulation
• cAMP-Independent Pathways: Studies on lipolytic mechanisms not requiring β-adrenergic receptor activation
• Signaling Cascades: Examination of kinase cascades, calcium signaling, and downstream effectors

Research protocols investigate how AOD9604 stimulates lipolysis through mechanisms distinct from catecholamines, providing insights into alternative fat mobilization pathways.

Adipocyte Metabolism and Function Research

Laboratory studies investigate AOD9604’s effects on adipocyte biology:

• Lipogenesis Inhibition: Examination of de novo lipogenesis suppression, ACC inhibition, FAS expression
• Fatty Acid Oxidation: Research on β-oxidation enhancement, CPT1 activity, mitochondrial function
• Adipocyte Differentiation: Studies on preadipocyte differentiation, PPARγ expression, adipogenesis
• Metabolic Gene Expression: Investigation of transcriptional programs affecting lipid metabolism
• Inflammatory Markers: Research on cytokine expression, macrophage infiltration, inflammatory signaling

Experimental models include 3T3-L1 adipocyte differentiation, primary adipocyte cultures, and adipose tissue explants.

Body Composition Research

Research applications extend to body composition investigation:

• Fat Mass Reduction: Examination of adipose tissue mass changes, depot-specific effects
• Lean Mass Preservation: Studies on muscle mass maintenance during fat loss
• Adipose Distribution: Research on visceral vs. subcutaneous fat depot responses
• Regional Specificity: Investigation of preferential effects on specific adipose depots
• Metabolic Outcomes: Examination of metabolic improvements associated with body composition changes

Laboratory protocols assess body composition using DEXA, MRI, or tissue weighing with correlation to metabolic parameters.

Growth Hormone Fragment Biology

AOD9604 enables investigation of hGH functional domains:

• Receptor-Independent Effects: Research on biological activities not requiring GH receptor activation
• Structure-Activity Relationships: Studies on which hGH regions confer specific biological effects
• Fragment vs. Full-Length: Comparison of fragment effects to full-length hGH actions
• Mechanism Dissection: Investigation of how C-terminal fragment exerts metabolic effects
• Receptor Identification: Research on potential alternative receptors or binding proteins

This research area addresses fundamental questions about growth hormone biology and functional domain organization.

Comparative Lipolytic Pathway Research

AOD9604 enables comparison of different lipolytic mechanisms:

• β-Adrenergic Stimulation: Comparison to isoproterenol, epinephrine-stimulated lipolysis
• Natriuretic Peptides: Comparison to ANP/BNP-mediated lipolysis
• Growth Hormone: Comparison to full-length hGH lipolytic effects
• Pathway Convergence: Investigation of common downstream effectors
• Synergistic Effects: Research on combined pathway activation

This comparative approach elucidates multiple parallel pathways regulating adipose tissue lipid mobilization.

Metabolic Disease Model Research

Laboratory studies investigate AOD9604 in metabolic contexts:

• Obesity Models: Research in diet-induced obesity examining fat mass reduction mechanisms
• Insulin Resistance: Studies assessing metabolic improvements without insulin antagonism
• Hepatic Steatosis: Investigation of liver fat reduction through enhanced peripheral lipolysis
• Metabolic Syndrome: Research on multiple metabolic parameter improvements
• Comparison to GH: Assessment of metabolic benefits without GH receptor-mediated side effects

Experimental protocols evaluate whether selective lipolytic stimulation provides metabolic benefits with improved safety profile.

Laboratory Handling and Storage Protocols

Lyophilized Powder Storage:

• Store at -20°C to -80°C in original sealed vial
• Protect from light and moisture
• Desiccated storage environment recommended
• Stability: 24+ months at -20°C
• Minimize temperature fluctuations

Reconstitution Guidelines:

• Reconstitute with sterile water, bacteriostatic water, or appropriate buffer
• Add solvent slowly down vial side
• Gentle swirling motion (avoid vigorous shaking)
• Allow complete dissolution (typically 1-2 minutes)
• Final pH 7.0-8.0 for optimal stability
• Consider reducing agent (DTT, β-mercaptoethanol) for disulfide bond studies

Reconstituted Solution Storage:

• Short-term: 4°C for up to 7 days
• Long-term: -20°C in single-use aliquots
• Avoid repeated freeze-thaw (maximum 2 cycles)
• Protect from light
• Oxidation sensitive due to disulfide bond and tyrosine

Stability Considerations:
The disulfide bond between Cys7 and Cys14 is important for biological activity. Avoid reducing conditions unless studying structure-activity relationships. Tyrosine residue susceptible to oxidation; minimize oxygen exposure.

Quality Assurance and Analytical Testing

Purity Analysis:

• HPLC: ≥98% purity
• Reversed-phase HPLC with UV detection at 214nm and 280nm (Tyr)
• Related substances: <2% total impurities

Structural Verification:

• ESI-MS: Confirms MW 1,815.08 Da
• Disulfide bond confirmation: Mass shift with/without reduction
• Amino acid analysis: Sequence composition verification
• Peptide content: 80-85% by weight (typical)

Contaminant Testing:

• Endotoxin: <5 EU/mg (LAL method)
• Heavy metals: <10 ppm per USP standards
• Residual solvents: Per ICH Q3C guidelines
• Water content: <8% (Karl Fischer)

Biological Activity:

• Lipolysis assay: Glycerol release from adipocytes
• Comparison to reference standard
• No GH receptor binding (negative control)

Documentation:

• Certificate of Analysis with complete data
• Batch traceability by lot number
• Third-party verification available
• Stability data for storage conditions

Research Considerations

Experimental Design:

1. Concentration Selection: In vitro adipocyte studies typically use 1-100 μg/mL ranges. In vivo studies require optimization based on model and objectives.

2. Disulfide Bond Importance: The Cys7-Cys14 bond is critical for activity. Maintain non-reducing conditions for functional studies.

3. Comparator Selection:

• Full-length hGH (to demonstrate receptor-independent effects)
• β-adrenergic agonists (to show distinct mechanism)
• Vehicle control

4. Model Selection:

• In vitro: 3T3-L1 adipocytes, primary adipocytes
• Ex vivo: Adipose tissue explants
• In vivo: DIO models, body composition assessment

5. Endpoint Assessment:

• Lipolysis: Glycerol and fatty acid release
• Gene expression: Lipid metabolism enzymes
• Body composition: Fat and lean mass
• Metabolic parameters: Without glucose/IGF-1 changes

Mechanism Investigation:

Key research questions:

• What is the molecular target of AOD9604?
• How does it activate lipolytic pathways without β-adrenergic receptors?
• Why are effects selective for adipose tissue?
• What is the relationship to full-length hGH actions?

GH Receptor Independence:

Critical verification that effects are GH receptor-independent:

• No IGF-1 elevation
• No effects on linear growth
• Activity in GH receptor knockout models
• No displacement of hGH from its receptor

Compliance and Safety Information

Regulatory Status:
AOD9604 is provided as a research chemical for in-vitro laboratory studies and preclinical research only. Not approved for human therapeutic use, dietary supplementation, or performance enhancement.

Intended Use:

• In-vitro adipocyte and lipid metabolism research
• In-vivo preclinical studies with IACUC approval
• Growth hormone fragment biology investigation
• Lipolysis mechanism research
• Academic and institutional research only

NOT Intended For:

• Human consumption or administration
• Athletic performance enhancement
• Therapeutic treatment or diagnosis
• Veterinary therapeutic use
• Dietary supplementation or weight management
• Non-research applications

Safety Protocols:

• Standard laboratory PPE required
• Handle in well-ventilated areas
• Follow institutional biosafety guidelines
• Proper waste disposal per regulations
• Consult SDS for detailed safety information

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