Effects of fluoxetine on immune parameters of the clam Ruditapes philippinarum.

Among emerging environmental contaminants, pharmaceuticals and personal care products (PPCPs) are a large group of substances used either by human for personal health and cosmetic reasons or by agribusiness to enhance growth or health of livestock. PPCPs are produced in large quantities and comprise numerous chemicals, including prescriptible drugs, veterinary drugs, diagnostic agents, fragrances, lotions, and cosmetics. As a consequence, main sources of PPCPs in the environment (aquatic in particular) are human activities, residues from both pharmaceutical manufacturing and hospitals, illicit drug use, veterinary drug use and agribusiness. Among pharmaceuticals, fluoxetine (a selective serotonin reuptake inhibitor) is an antidepressant commonly used for treating depression and other psychological disorders. Despite its wide use, information is lacking about the effects of fluoxetine on non-target species. To fill this gap, in the present study the effects of fluoxetine on some important immune parameters of the clam Ruditapes philippinarum were evaluated for the first time. Clams (25 per concentration) were exposed for 7 days to differing fluoxetine concentrations (0, 1, 5, 25, 125, 625 µg/L), and haemolymph was collected from the anterior adductor muscle. Eight pools of haemolymph (from 3 bivalves each) were prepared for each experimental condition, and total haemocyte count (THC), Neutral Red uptake (NRU), lysozyme activity in cell-free haemolymph (CFH) and haemocyte proliferation were measured. An increasing trend was observed in THC values, the difference being significant at 25 µg/L, with respect to controls. NRU was shown to decrease significantly in haemocytes of clams exposed to 1 and 5 µg/L, compared with controls, whereas NRU increased to control levels in clams exposed to the highest fluoxetine concentrations. Haemocyte proliferation increased significantly in animals exposed to 25, 125 and 625 µg/L, with respect to controls. Conversely, no significant alterations were observed in CFH lysozyme activity. Although preliminary, the results obtained demonstrate that fluoxetine influence markedly immune parameters in clams, even at environmentally realistic concentrations.