Leptin inhibits which first order neurons in the orexigenic pathway?

Leptin plays a crucial role in regulating energy balance and appetite. It is a hormone produced by adipose (fat) tissue that signals the status of energy stores to the brain, particularly to the hypothalamus. In the context of the orexigenic (appetite-stimulating) pathway, leptin has a specific inhibitory effect.

Leptin inhibits the activity of neurons that are part of the orexigenic pathway, specifically targeting neuropeptide Y (NPY) neurons and agouti-related peptide (AGRP) neurons. Both of these neuron types are critical players in stimulating appetite. By inhibiting the activity of these neurons, leptin helps to reduce food intake and promote energy expenditure. This mechanism is part of the body's way of achieving homeostasis in energy balance; as fat stores increase and leptin levels rise, the inhibitory effect on NPY and AGRP neurons effectively suppresses hunger signals.

Understanding the relationship between leptin and these first-order neurons is essential for comprehending how dysregulation of this pathway can contribute to obesity and other metabolic disorders. By correctly identifying that leptin inhibits both NPY and AGRP neurons, one gains insight into the complex interplay of hormones and neuropeptides that govern appetite regulation