Regulatory peptides of the gut and brain

The concept of the gut-brain axis has emerged from the recent demonstration, mainly by radioimmunoassay and immunohistochemistry, that many peptides are common to both gut and brain cells. The general term regulatory peptide is at present the most appropriate for these peptides until more is known about their precise hormonal, neurotransmitter and neuromodulator activities. Consideration of possible local endocrine (paracrine) and neuroendocrine secretion necessitates re-evaluation of the importance of peripheral regulatory peptide concentrations. Central and peripheral administration of these peptides is a useful way to establish their potential regulatory roles in endocrine and nervous pathways. The concept of the gut-brain axis demonstrates the intimate relations between endocrinology and neuroendocrinology.