Leptin is a peptide hormone primarily secreted by white adipose tissue (fat cells). Its level in the blood is proportional to the body's fat mass. Its primary site of action is the hypothalamus, specifically neurons in the arcuate nucleus. Leptin acts as a critical 'adipostat' signal, informing the brain about long-term energy stores. When fat mass is sufficient, high leptin levels signal the hypothalamus to suppress appetite (by inhibiting orexigenic neurons like those producing NPY) and increase energy expenditure. When fat stores are low, leptin levels drop, stimulating hunger and conserving energy. Defects in leptin signaling (leptin deficiency or leptin receptor resistance) are associated with severe obesity. Leptin thus forms a key feedback loop between peripheral energy stores and the brain's feeding centers.

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Zambia

• Joseph Soko – 101 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies