Which hormone's increased production renders insulin less effective and is associated with elevated neuropeptide Y release?

The hormone associated with increased production rendering insulin less effective while being linked to elevated neuropeptide Y release is cortisol. Cortisol is a stress hormone produced by the adrenal glands in response to stress and low blood glucose levels. When cortisol levels are high, it can lead to insulin resistance, meaning the body's cells become less responsive to insulin. This inefficiency in insulin's function can contribute to higher blood sugar levels and can also promote fat accumulation, which is often observed in conditions like metabolic syndrome.

Additionally, cortisol is known to influence neuropeptide Y, a peptide that plays a role in regulating appetite, stress response, and energy balance. Elevated cortisol levels can stimulate the release of neuropeptide Y, which is linked to increased hunger and food intake, further compounding the effects of insulin resistance.

In contrast, the other hormones listed—estrogen, serotonin, and melatonin—do not have the same direct relationship with insulin resistance and neuropeptide Y modulation. Estrogen primarily influences various bodily functions, including reproductive health and metabolism, but it does not directly induce insulin resistance in the same way cortisol does. Serotonin is primarily a neurotransmitter associated with mood regulation and does not have a significant effect on insulin effectiveness. Melatonin regulates sleep patterns