Methylmercury and Fish Nutrients in Experimental Models

Abstract

The primary source of human exposure to methylmercury is fish and seafood, which are also the source of important nutrients. Developmental methylmercury exposure disrupts the formation of key brain structures, including the cortex, and has behavioral effects reflective of this disruption. Adult-onset exposure has a different pattern of effects, which emphasizes sensorimotor function. Some nutrients, like the omega-3 fatty acids and especially docosahexaenoic acid (DHA), are important for neural development and function. Others, like selenium, may be important, but they are less well understood. Selenium is, under some circumstances, protective against methylmercury exposure. This chapter summarizes studies using experimental models in which methylmercury exposure is examined with and without conjoint exposure to diets rich in selenium or DHA. Both adult-onset and developmental exposures are considered. Developmental methylmercury exposure has effects that extend into adulthood and aging. The pattern of effects is consistent with a hypothesis that development exposure disrupts reward processing, perhaps through disruption of dopamine neurotransmitter systems and cortical development. Selenium is protective against adult-onset but not developmental methylmercury exposure. DHA, which has benefits of its own, was not protective against either form of methylmercury exposure in animal models.