Appetite is increased by ?
**Core Concept**
Appetite regulation involves a complex interplay of hormonal, neural, and environmental factors. The hypothalamus plays a crucial role in modulating appetite through various neurotransmitters and hormones, including ghrelin, leptin, and insulin.
**Why the Correct Answer is Right**
The correct answer is dopamine. Dopamine is an excitatory neurotransmitter that stimulates appetite and food intake. It acts on dopamine receptors in the hypothalamus, promoting the sensation of pleasure and reward associated with eating. This is particularly relevant in the context of the brain's reward system, which is activated during the consumption of palatable foods.
**Why Each Wrong Option is Incorrect**
**Option A:** Insulin is a hormone that inhibits appetite by signaling satiety and reducing glucose levels in the blood. It is not associated with increased appetite.
**Option B:** Leptin is a hormone produced by adipose tissue that suppresses appetite by signaling energy stores are sufficient. It is not associated with increased appetite.
**Option C:** Ghrelin is a hormone produced by the stomach that stimulates appetite by signaling energy stores are depleted. While ghrelin does increase appetite, dopamine is a more direct and potent stimulator of appetite.
**Clinical Pearl / High-Yield Fact**
The brain's reward system, involving dopamine release, is often hijacked by food manufacturers to create highly palatable and addictive foods. This can lead to overeating and obesity.
**Correct Answer: C. Ghrelin**