title: Excess dietary vitamin B-6 alters startle behavior of rats.
abstract: Excessive intakes of vitamin B-6 can produce peripheral nervous system abnormalities, but few reports of central nervous system effects exist. We measured startle response, a central nervous system reflex, in rats fed excess pyridoxine to determine if subtle effects on central nervous system function could be detected. Female Long-Evans rats (218 g; n = 12) were fed either 1, 10, 100, 200 or 300 times the requirement of pyridoxine HCl (7 mg/kg) for 7 wk. Startle behavior was assessed weekly in chambers that allowed quantification of movement in response to stimuli. Food intake and body weights did not differ among groups (P > 0.1), and urinary vitamin B-6 excretion reflected intake (P < 0.001). Overt toxicity was not observed. There was a marginally significant effect of pyridoxine intake over time (P = 0.053) on the amplitude of response to a startling acoustic stimulus (117 dB, 40 ms) administered alone; the response appeared attenuated at the three highest pyridoxine concentrations. When the same stimulus was preceded by either a 70- or 75-dB prepulse (40 ms), responses of groups fed the two highest pyridoxine concentrations were significantly reduced relative to those fed the two lowest concentrations (P < 0.05). No effect of diet was seen with a startling tactile stimulus. Changes in central nervous system function were detected in rats fed excess vitamin B-6 using techniques of startle behavior measurement.
authors.affiliation: Western Human Nutrition Research Center, United States Department of Agriculture, Presidio of San Francisco, CA 94129.
authors.forename: M C
authors.initials: MC
authors.lastname: Schaeffer
mesh_terms: D000161:Acoustic Stimulation; D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D004032:Diet; D005260:Female; D011736:Pyridoxine / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D013216:Reflex, Startle / Q000187:drug effects*; D014110:Touch
chemical_list: D011736:Pyridoxine