Environmental Stressors and Neurobiological Features of Marine Teleosts: Histamine Receptors as Targets

The excessive levels of aquatic endocrine disruptors (EDs) and namely heavy metals plus xenoestrogens account for irregular gas exchange processes, reduced reproductive success, as well as abnormal social interactions of marine teleost fish. These effects at the encephalic level appear to derive from the interference of major signaling factors such as histamine (HA) neuroreceptor subtypes (H(1-4)R). HA is one of the main biogenic amine neuronal system responsible for regulatory homeostatic functions, including sleep-wake rhythms and motor activities. Recently, interests have begun to focus attention on toxic effects of some heavy metals, i.e., cadmium (Cd) and lead (Pb), and how they are capable of eliciting motor dysfunctions via HAergic receptor subtypes. Interestingly, subtype 2 (H(2)R) proved to be a preferential target of heavy metal-dependent altered locomotor maneuvers, as displayed by its specific antagonist (cimetidine)-inducing non-synchronous swimming activities (Santos et al., 2003, Pharmacol Biochem Behav 75:25-33). Conversely, although the preferential H(3)R antagonist (thioperamide) did not interfere with normal swimming behaviors, it surprisingly did ameliorate heavy metal-dependent hyperactive states (Giusi et al., 2008, Toxicol Appl Pharmacol 227:248-256). In the case of the xenoestrogens atrazine and endosulfan, their actions tend to mostly account for feeding alterations through hypothalamic H(3)R-dependent mechanisms. The aim of this review is to highlight the type of ED-HAergic neuroreceptor variations that are involved in stressor-dependent neurobehavioral responses of commercially valuable marine teleosts.