The American journal of physiologyAug 1, 1990

Effects of brainstem neuropeptides Y and YY on eating and other behaviors

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 28, 2026

Abstract

Injection of neuropeptide Y (NPY) or peptide YY (PYY) into the fourth ventricle produced a significant dose-related increase in food intake.

PYY was more effective than NPY in enhancing food intake and decreasing the time it took to start eating.
Both peptides increased water intake only when food was present, indicating a lack of neural mechanisms for water intake independent of food.
During a 90-minute feeding test, both peptides led to increased eating time and decreased grooming behaviors.
PYY reduced sleep duration and increased exploratory activity, while NPY did not show these effects.

Simplified

We studied the effect of fourth intracerebroventricular administration of neuropeptide Y (NPY) and peptide YY (PYY) on ingestive and other behaviors in awake nondeprived rats. Injection of NPY or PYY into the fourth ventricle produced a significant dose-related increase in food intake and reduction in the latency to eat. PYY was more potent than NPY in increasing food intake and decreasing latency to eat, suggesting that PYY-preferring receptors sensitive to the orexigenic effects of NPY and PYY exist in the hindbrain. In addition, both peptides increased water intake when food was present but not when food was absent, suggesting that a neural substrate supporting a direct action of NPY and PYY on water intake is not present in the hindbrain. In time sampling of behaviors occurring during a 90-min feeding test, we found that both peptides increased the time spent eating and reduced grooming. In addition PYY, but not NPY, reduced apparent sleep and increased exploratory activity. This suggests that PYY, but not NPY, influences a hindbrain neural substrate involved in sleep and activity.

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Effects of brainstem neuropeptides Y and YY on eating and other behaviors

Abstract

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