VPT 311: General and Systemic Veterinary Pharmacology (2+1)

CORTICOTROPHIN AND RELATED PEPTIDES

Corticotrophin releasing hormone

• This hormone stimulates synthesis and secretion of ACTH by pituitary corticotrophs.
• This hormone appears to exert its effect on ACTH release through both adenylate cyclase and calcium-calmodulin signal transduction systems.

Adrenocorticotrophin

• ACTH stimulates the secretion of glucocorticoids, mineralocorticoids and adrenal androgens
• It acts by increasing the activity of the rate limiting agent in steroid synthesis and converts cholesterol to pregnonolone.
• ACTH also stimulates adrenal hypertrophy and hyperplasia.
• Corticotrpin and ACTH are used as diagnostic tools to test adrenocorticotroph and adrenal function reserve. ACTH can be used for all the purposes for which glucocorticoids are recommended.
• The advantage of ACTH is that it leads to suppression of pituitary over time while glucocorticoids suppress the pituitary and adrenal cortex quickly.
• ACTH gel preparations are derived from pig pituitaries. Both porcine and synthetic ACTH are well absorbed after intramuscular administration.
• However, its disadvantage is that it cannot be administered by oral route unlike glucocorticoids.