Unraveling Tyrosine Hydroxylase in the Brain of a Crustacean: An Integrative Investigation Using Different Approaches.

Tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine (DA) synthesis, is conserved across most animal phyla. DA regulates motor activity, sensory processing motivation, neural homeostasis, and protection against oxidative stress. TH and DA have been described in vertebrates and in some invertebrates, including arthropods. This study investigated the anatomical location of TH and DA and characterized the biochemical and molecular structure of TH in the brain of the mangrove crab Ucides cordatus. This species is a useful environmental model for neurodegeneration studies, due to its occurrence in metal-contaminated mangrove ecosystems, and as prey of other species, including humans. Using immunohistochemistry, immunoblotting, and structural modeling, we mapped TH presence and distribution in the crustacean brain and analyzed its molecular and evolutionary characteristics. Our results revealed a TH fragment structurally similar to fragments found in 21 other species and in a complex dopaminergic network in U. cordatus, characterized by diverse neuronal morphologies, widespread projections, and sensitivity to dopaminergic neurotoxins. These findings may support further studies on catecholaminergic neurobiology.