### PYY Gene Overview

**Gene Symbol**: PYY  
**Type**: Protein-coding gene  
**Location**: Chromosome 17 (17p13.3) in humans  
**Function**: The PYY gene encodes prepro-peptide that is cleaved to produce two active peptides (PYY1-36 and PYY3-36), which function in energy homeostasis, gastrointestinal motility, and secretion regulation.

### 1. Associated Genes
While the summaries provided focus on PYY, the PYY gene is known to interact with several other genes involved in the neuropeptide Y (NPY) signaling pathway and appetite regulation, including:
- **NPY**: Neuropeptide Y, which is involved in energy balance and is a major neuropeptide that interacts with PYY.
- **Y Receptor Genes (e.g., NPY1R, NPY2R, NPY5R)**: Neuropeptide Y receptors that respond to the binding of PYY and regulate various physiological processes.
- **LEP (Leptin)**: Leptin signaling plays a role in energy homeostasis and appetite regulation, interacting with the pathways influenced by PYY.
- **GHRL (Ghrelin)**: Ghrelin, another appetite-regulating peptide, may interact with PYY signaling in the hypothalamus.

### 2. Aging and Age-related Diseases
Research indicates that variations in the PYY gene may influence body weight regulation and metabolic disorders, which can be associated with aging. Specific details include:
- **Obesity**: Rare polymorphisms in PYY may relate to a predisposition to obesity, a condition that becomes increasingly prevalent with age.
- **Anorexia Nervosa**: Elevated levels of PYY have been observed in individuals with anorexia nervosa, which may worsen with age and contribute to age-related nutritional issues.
- **Metabolic Syndrome**: Alterations in PYY signaling could be linked to metabolic syndrome, which includes age-associated conditions like type 2 diabetes and cardiovascular diseases.

### 3. Drug Interactions
There are no specific drugs that target the PYY gene directly, but various drug classes may influence its pathways indirectly due to their roles in appetite regulation and metabolism. These include:
- **Appetite Suppressants**: Drugs designed to modulate appetite, such as orlistat and phentermine, may indirectly affect levels of PYY.
- **Glucagon-like Peptide-1 (GLP-1) Agonists**: Medications like liraglutide can influence gut peptides including PYY and are used in obesity and type 2 diabetes management.
- **Antipsychotics**: Some atypical antipsychotic medications may alter weight and appetite by impacting neuropeptidergic pathways inclusive of PYY.

### 4. Pathways and Biological Processes
PYY is involved in several pathways and biological processes, including:
- **Neuropeptide Signaling Pathway**: Involvement in the signaling cascades associated with neuropeptides.
- **Gut-Brain Axis**: Plays a critical role in the signaling from the gut to the CNS affecting appetite and metabolic regulation.
- **Regulation of Energy Homeostasis**: Involved in processes that regulate hunger and digestion, particularly after food intake.
- **Gastrointestinal Motility**: Inhibitory role on gastric motility and gastric emptying, affecting digestive processes.
- **Vasoconstriction**: Functionally linked to modulation of vascular tone in various tissues.

In summary, the PYY gene plays a vital role in regulating many physiological processes, especially in terms of appetite and energy balance, with implications in various metabolic disorders and relationships with aging and drug interactions.