Which of the following hormones is NOT typically lipid-soluble?

Adrenaline, also known as epinephrine, is not typically lipid-soluble. This hormone belongs to the catecholamine family, which is derived from the amino acid tyrosine. Catecholamines are characterized by their polar structure, which prevents them from easily crossing the lipid bilayer of cell membranes. Instead of being lipid-soluble, adrenaline is water-soluble and circulates freely in the bloodstream, binding to receptors on the surface of target cells to exert its physiological effects.

In contrast, hormones such as estrogen and testosterone, which are steroid hormones, and thyroid hormone, which is derived from the amino acid tyrosine but has a lipid-soluble component, can easily pass through cell membranes due to their lipid-soluble nature, allowing them to bind to intracellular receptors and directly influence gene expression. This distinction is crucial in understanding how different hormones interact with their target cells and the mechanism of their action in the body.