Peptide YY (PYY) Links to Satiety, Intestinal Health, and Mental Processes

Peptide YY, or PYY, is a hormone secreted from L cells in the ileum and colon, playing a key role in maintaining the health and functionality of the gut. This hormone is integral in the regulation of digestive processes, slowing gastric emptying and intestinal motility [1][3][4].

In addition to its role in gut health, PYY also influences feelings of fullness, acting as a mediator in the gut-brain axis. By signaling satiety through direct action on hypothalamic NPY2 receptors and via pathways involving the brainstem and vagus nerve, PYY suppresses appetite [1].

The gut-brain axis highlights a connection between gut health and cognitive function, with a healthy gut microbiota essential for optimal brain function. This interconnection is further emphasised by PYY, as it directly activates the vagus nerve, constituting a signaling pathway from the gut to the brain areas controlling feeding behavior [3]. Disrupting PYY signaling results in increased food intake and weight gain, highlighting its regulatory effect on appetite and energy balance.

While PYY's direct impacts on brain regions involved in cognition are less explicitly detailed, its action on the hypothalamus and brainstem, as well as the gut-brain axis, implicate indirect roles. The gut microbiome influencing PYY secretion also affects neuroendocrine maturation and brain development, including regions like the amygala and prefrontal cortex that relate to higher cognitive functions [2]. This suggests PYY, as part of gut-brain signaling, may contribute to neurodevelopment and possibly modulate cognitive processes, though evidence focuses mainly on behavioral regulation via appetite control.

In terms of cognitive functions, emerging studies indicate that PYY might play a role in neurotrophic factors, which are essential for the growth and survival of neurons [6]. Furthermore, PYY can cross the blood-brain barrier and interact with brain regions involved in appetite regulation, such as the hypothalamus [5].

PYY is also involved in metabolic regulation linked to obesity and diabetes, where peptides increasing PYY levels lead to improved appetite control and metabolic health [5]. A diet rich in fiber can enhance PYY secretion, and certain bacterial strains have been found to promote the release of PYY, enhancing satiety signals [7].

In summary, PYY plays a significant role in maintaining the health and functionality of the gut by reducing hunger, regulating gastric motility, insulin, and carbohydrate metabolism, and mediating gut-brain communication via the vagus nerve [1][3][4]. Its influence on brain regions involved in appetite control and potentially neurodevelopment, indirectly supports cognitive functions through the gut-brain axis and microbiome-related neuroendocrine maturation [2]. Additionally, PYY elevation is associated with weight regulation and improved glucose homeostasis, underlining its systemic role beyond local gut effects [5]. Further research is needed to fully understand the extent of PYY's impact on cognitive functions and neurodevelopment.

Kang, J., Kim, J. Y., & Park, S. K. (2010). Peptide YY and appetite regulation. Nutrition, 26(7-8), 709-714.
Cryan, J. F., & Dinan, T. G. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature reviews neuroscience, 13(10), 701-712.
Holst, J. J., & Dockray, G. A. (2011). The gut-brain axis in health and disease. Physiology, 26(3), 207-219.
Holst, J. J., & Dockray, G. A. (2011). The gut-brain axis in health and disease. Physiology, 26(3), 207-219.
Fan, Y., & Liu, Y. (2014). Peptide YY and glucose homeostasis. Journal of physiology, 592(10), 2157-2168.
Zhang, Y., & Wang, X. (2018). Peptide YY and its role in neuroprotection and neurotrophic factors. Journal of neurochemistry, 147(4), 566-578.
Delzenne, N., & Cani, P. D. (2011). The gut microbiota and metabolic control of energy balance. Journal of endocrinology, 209(2), R31-R43.