Effects of sodium fluoride on locomotor behavior and a few biochemical parameters in rats

Spontaneous motor activity and motor coordination were tested in adult fema le rats after treating with sodium fluoride at 20 or 40 mg/kg dose level da ily for 60 days, using an activity chamber and a rota-rod apparatus, respec tively. Total protein concentrations were determined in skeletal muscle, li ver and serum of similarly treated animals. The activities of total choline sterase and acetylcholinesterase were determined in blood rind brain region s, respectively. Sodium fluoride treatment suppressed spontaneous motor act ivity. But no change was observed in the motor coordination of these animal s. Tissue and serum protein concentrations were decreased. Cholinesterase a ctivity was decreased in the blood and not in brain regions. A failure of s odium fluoride to impair motor coordination indicated that neuromuscular fu nction required for a forced task was not deteriorated in these animals, al though skeletal muscles were deprived of protein and blood cholinesterase a ctivity was suppressed. A suppression of spontaneous motor activity suggest s that fluoride has, by a central action, inhibited motivation of these ani mals to exhibit locomotor behavior. A cholinergic mechanism through a chang e in the activity of acetylcholinesterase may not account for this effect, since sodium fluoride treatment did not alter the activity this enzyme in b rain regions. However, an involvement of monoamines may be proposed in view of previously reported finding that excessive fluoride intake has decrease d the concentrations of 5-hydroxyindoleacetic acid and increased that of no repinephrine in rat brain. (C) 1998 Elsevier Science B.V. All rights reserv ed.