Exposure to dietary mercury alters cognition and behavior of zebra finches.

Environmental stressors can negatively affect avian cognitive abilities, potentially reducing fitness, for example by altering response to predators, display to mates, or memory of locations of food. We expand on current knowledge by investigating the effects of dietary mercury, a ubiquitous environmental pollutant and known neurotoxin, on avian cognition. Zebra finches Taeniopygia guttata were dosed for their entire lives with sub-lethal levels of mercury, at the environmentally relevant dose of 1.2 parts per million. In our first study, we compared the dosed birds with controls of the same age using tests of three cognitive abilities: spatial memory, inhibitory control, and color association. In the spatial memory assay, birds were tested on their ability to learn and remember the location of hidden food in their cage. The inhibitory control assay measured their ability to ignore visible but inaccessible food in favor of a learned behavior that provided the same reward. Finally, the color association task tested each bird's ability to associate a specific color with the presence of hidden food. Dietary mercury negatively affected spatial memory ability but not inhibitory control or color association. Our second study focused on three behavioral assays not tied to a specific skill or problem-solving: activity level, neophobia, and social dominance. Zebra finches exposed to dietary mercury throughout their lives were subordinate to, and more active than, control birds. We found no evidence that mercury exposure influenced our metric of neophobia. Together, these results suggest that sub-lethal exposure to environmental mercury selectively harms neurological pathways that control different cognitive abilities, with complex effects on behavior and fitness.

Opioid-induced pruritus.

Opioid analgesics are commonly used medications for the treatment of acute and chronic pain syndromes associated with multiple disease states. However, their use is often limited by adverse effects. Opioid-induced pruritus (OIP) is one of the most common adverse effects, affecting patients on oral and neuraxial opioids. Although not life-threatening, pruritus is an unpleasant side effect potentially contributing to patient discomfort, decreased quality of life, and noncompliance. The occurrence of pruritus varies with the type of opioid, dose, and method of administration. Pharmacists can make interventions that will optimize control of, or reduce the incidence of, OIP. An understanding of the receptors, mechanisms, incidence, and pharmacological therapies available to manage OIP is required knowledge for practitioners caring for patients who use opioids.