title: Acute effects of oral low doses of pyridostigmine on simple visual discrimination and unconditioned consummatory acts in rats.
abstract: Pyridostigmine bromide (Pyr), a reversible cholinesterase inhibitor, is currently suggested to be the most effective pretreatment drug against intoxication with potent organophosphates (OP). This investigation was conducted to determine if oral low doses of Pyr would affect performance of a simple visual discrimination task, and further to assess the alterations of motor or motivational function that might underlie the performance deficits in the water-deprived rats. Rats were trained extensively on a successive light-intensity discrimination implemented with the use of a multiple schedule. The multiple schedule consisted of one fixed-ratio (FR-10) and one differential reinforcement of low rates (DRL-10 s) component, which were signalled by the 10-s discriminative stimuli of bright (S+) and dim (S-) houselights, respectively, in simple alternation. The light intensity difference (S-/S+) was about 0.6. Pyr, at doses (3-12 mg/kg), which did not cause overt symptoms, moderately decreased S+ respondings but did not affect S- respondings. The ratio of S+/S- respondings, an index of discrimination performance, was moderately decreased. Over the range of doses evaluated, Pyr also attenuated the corresponding water intake in a dose-dependent manner, but it did not significantly affect locomotor activity. The lowest effective doses of the above affected behaviors were virtually identical (6 mg/kg). These results suggest that the disruptive effects of a single oral low dose of Pyr on the rat operant performance involve motivational dysfunction rather than motor impairment.
authors.affiliation: Laboratory of Behavioral Pharmacology and Toxicology, Chemical Systems Division CSIST, Taiwan, R.O.C.
authors.forename: W F
authors.initials: WF
authors.lastname: Liu
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects*; D008297:Male; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D010775:Photic Stimulation; D011729:Pyridostigmine Bromide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule; D014868:Water Deprivation
chemical_list: D011729:Pyridostigmine Bromide