Peptide histidine isoleucineamide

Peptide histidine isoleucineamide (PHI) is a neuropeptide that is found in the nervous system of many animals, including humans. It is a member of the vasoactive intestinal peptide (VIP) family of peptides and is closely related to peptide histidine methionine (PHM).

Structure and Function

PHI is a 27-amino acid peptide that is derived from the same precursor molecule as VIP. The precursor molecule, prepro-VIP, is cleaved by prohormone convertase enzymes to produce VIP, PHI, and other peptides. PHI shares the same N-terminal histidine and C-terminal isoleucine-amide residues as VIP, but differs in the sequence of the remaining amino acids.

PHI functions as a neurotransmitter and neuromodulator in the nervous system. It is involved in a variety of physiological processes, including the regulation of blood pressure, heart rate, and gastrointestinal motility. PHI also has vasodilatory effects and can stimulate the secretion of insulin and other hormones.

Clinical Significance

Abnormal levels of PHI have been associated with several diseases, including diabetes, hypertension, and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. PHI may also play a role in the regulation of appetite and body weight, and alterations in PHI signaling could contribute to obesity and eating disorders.

Research is ongoing to develop drugs that can modulate the activity of PHI and other VIP-related peptides for the treatment of these and other conditions. However, the complex nature of PHI's interactions with other systems in the body makes this a challenging area of study.

See Also

• Neuropeptide
• Vasoactive intestinal peptide
• Peptide histidine methionine