What are the most common peptides in males?

Common Male Peptides

The most common peptides in males include B-type natriuretic peptide (BNP), relaxin family peptides, and growth hormone-releasing peptides, with BNP being particularly significant for cardiovascular health monitoring.

Natriuretic Peptides

• B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are important cardiac biomarkers that are naturally produced in the heart, primarily in the ventricles during cardiac stress 1
• BNP is primarily produced by cardiac myocytes and fibroblasts in response to myocardial stretch mediated by pressure and volume 1
• Normal BNP levels in males are typically lower than in females:
  • Young adult males: <25 pg/ml 1
  • Males 45-59 years: <100 pg/ml 1
  • Males >60 years: <98 pg/ml 1
• Males consistently have lower BNP levels than females, likely due to androgen suppression of pro-BNP synthesis 1

Relaxin Family Peptides

• Relaxin is an important peptide in males that is produced in the male reproductive tract and is present in semen 1
• In males, relaxin increases sperm motility and enhances penetration into oocytes 1
• INSL3 (Insulin-like peptide 3) is another important relaxin family peptide in males that acts on RXFP2 receptors 1
• RXFP2 receptors are found in the testis, specifically in spermatocytes, spermatids, Leydig cells, and epididymal epithelium 1
• INSL3/RXFP2 signaling plays a critical role in testicular descent, as evidenced by bilateral cryptorchidism in INSL3 and RXFP2 knockout mice 1

Growth Hormone-Related Peptides

• Growth hormone-releasing peptides (GHRPs) are synthetic peptides with potent stimulatory effects on growth hormone secretion 2, 3
• Common GHRPs include sermorelin, GHRP-2, GHRP-6, ibutamoren, and ipamorelin 3
• Sermorelin is a 29-amino acid analogue of human growth hormone-releasing hormone (GHRH) that stimulates growth hormone secretion from the anterior pituitary 4
• GHRPs act through specific receptors at both pituitary and hypothalamic levels 2, 5
• These peptides can significantly improve body composition by reducing fat and increasing muscle mass in hypogonadal males 3

Clinical Significance

• BNP and NT-proBNP are crucial biomarkers for diagnosing and monitoring cardiac conditions, particularly heart failure 1
• Elevated BNP levels are associated with increased risk of perioperative mortality and morbidity 1
• Higher body mass index results in lower normal values of BNP, which is an important consideration when interpreting results in overweight or obese males 1
• Androstenedione, while not a peptide but a steroid hormone, serves as a precursor to testosterone and is sometimes measured alongside other hormones when evaluating male reproductive disorders 6

Therapeutic Applications

• GHRPs have emerged as potential adjunctive therapies for symptoms of hypogonadism, particularly for improving body composition 3
• Sermorelin at doses of 1 μg/kg bodyweight intravenously can be used as a diagnostic test for growth hormone deficiency 4
• Some GHRPs are orally active, making them potentially convenient therapeutic options 5
• The combination of GHRPs with GHRH produces synergistic effects on growth hormone release 5

Monitoring Considerations

• When measuring BNP levels in males, age-specific reference ranges should be used for proper interpretation 1
• Factors that can affect BNP levels include age, renal function, and body mass index 1
• Regular monitoring of BNP may be valuable in males with cardiovascular risk factors or established heart disease 1