Peptide YY (3-36) represents a high percentage of total PYY immunoreactivity in preterm and full-term infants and correlates independently with markers of adiposity and serum ghrelin concentrations

Early growth and postprandial appetite regulatory hormone responses

Strong epidemiological evidence suggests that slow prenatal or postnatal growth is associated with an increased risk of CVD and other metabolic diseases. However, little is known whether early growth affects postprandial metabolism and, especially, the appetite regulatory hormone system. Therefore, we investigated the impact of early growth on postprandial appetite regulatory hormone responses to two high-protein and two high-fat content meals. Healthy, 65–75-year-old volunteers from the Helsinki Birth Cohort Study were recruited; twelve with a slow increase in BMI during the first year of life (SGI group) and twelve controls. Subjects ate a test meal (whey meal, casein meal, SFA meal and PUFA meal) once in a random order. Plasma glucose, insulin, TAG, NEFA, ghrelin, peptide tyrosine-tyrosine (PYY), glucose-dependent insulinotropic peptide, glucagon-like peptide-1 and a satiety profile were measured in the fasting state and for 4 h after each test meal. Compared with the controls, the SGI group had about 1·5-fold higher insulin responses after the whey meal (P= 0·037), casein meal (P= 0·023) and PUFA meal (P= 0·002). TAG responses were 34–69 % higher for the SGI group, but only the PUFA-meal responses differed significantly between the groups. The PYY response of the SGI group was 44 % higher after the whey meal (P= 0·046) and 115 % higher after the casein meal (P= 0·025) compared with the controls. No other statistically significant differences were seen between the groups. In conclusion, early growth may have a role in programming appetite regulatory hormone secretion in later life. Slow early growth is also associated with higher postprandial insulin and TAG responses but not with incretin levels.

Peptide YY

PURPOSE OF REVIEW

This review discusses recent studies examining the effects of peptide YY on energy homeostasis, highlights the emerging hedonic effects of peptide YY and evaluates the therapeutic potential of the peptide YY system.

RECENT FINDINGS

A role for exogenous PYY3-36 as an anorectic agent in obese humans and rodents has been established and weight loss effects demonstrated in obese rodents. New lines of evidence support a role for endogenous peptide YY in regulating energy homeostasis. The NPY-Y2 receptor mediates the anorectic actions of PYY3-36 with rodent studies implicating the hypothalamus, vagus and brainstem as key target sites. Functional imaging in humans has confirmed that PYY3-36 activates brainstem and hypothalamic regions. The greatest effects, however, were observed within the orbitofrontal cortex, a brain region involved in reward processing. Further evidence for a hedonic role for PYY3-36 is supported by rodent studies showing that PYY3-36 decreases the motivation to seek high-fat food. Rodent studies using selective Y2 agonists and strategies combining PYY3-36/Y2 agonists with other anorectic agents have revealed increased anorectic and weight-reducing effects.

SUMMARY

Peptide YY plays a role in the integrative regulation of metabolism. The emerging hedonic effects of peptide YY together with the weight-reducing effects observed in obese rodents suggest that targeting the peptide YY system may offer a therapeutic strategy for obesity.