Why can neurotransmitter receptors in the brain not become damaged with excessive use of say drugs, but insulin receptors can become damaged when consuming too much sugar?

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Why can neurotransmitter receptors in the brain not become damaged with excessive use of say drugs, but insulin receptors can become damaged when consuming too much sugar?

In: Biology

Okay there’s a big misunderstanding here, I’m not actually sure where to start. Receptors don’t get “damaged,” at least not even remotely in the way you think. Receptors are just proteins, they bind a ligand and they do some effect in turn. You have a huge amount of these receptors per cell. Activating a receptor excessively with its ligand or with a drug will in turn excessively sitmulate its downstream effects. Cells sense there is too much signaling coming via that pathway and so they adapt by, for example, reducing the amount of new receptors they make. Receptors are constantly in a state of dynamic recycling. They often get internalized and destroyed and the cell makes new ones. If the cell decides to make less or destroy more, you have less of that receptor on the cell membrane, and then less signaling despite excessive ligand/drug. So it’s an adaptation.

Insulin is a hormone, it binds its receptor to induce changes in cells like uptake of glucose and anabolic things (building things). Sugar increases the level of the insulin released, sugar has no “receptor,” it’s sensed by the beta cells. Type 2 diabetes onset happens when two factors occur. First the insulin resistance rises (meaning cells around the body don’t respond to insulin as well as they did before) and second, the beta cells try to compensate by making and secreting more insulin until a point where they decompensate meaning they cannot meet the demands. At that point, blood sugar begins to rise even at basal levels. Why insulin resistance happens? That’s not entirely known but the evidence shows its far more complex than a simple adaptation at the single cell level. It has to do with a bunch of other hormones that are affected by a bunch of things like obesity.

It’s a common misconception that insulin receptors become damaged by consuming too much sugar. They can however, become damaged by increased levels of fat tissue. The fat cells known as adipocytes secrete inflammatory cells, leading to high levels of systemic inflammation that can damage the insulin receptors reducing the ability for tissues to uptake glucose into the cell. Which leads to hyperglycemia.