Effects of maternal vitamin B-6 deficiency on specific regions of developing rat brain: the extrapyramidal motor system.

Progeny of rats deficient in vitamin B-6 exhibit gross neurological symptoms during a critical period of brain development, which may be related to abnormalities of the extrapyramidal motor system. In this study concentrations of the neurotransmitters, gamma-aminobutyric acid (GABA) and dopamine (DA) and certain amino acids were determined in substantia nigra (SN) and caudate/putamen (C/P) in progeny of dams fed diets containing either deficient (D), 0.6 or control (C), 7.0 mg pyridoxine x HCl (PN x HCl) per kilogram diet throughout growth, gestation and lactation. These measurements in C/P were correlated with the number of synapses. Analysis of brains of pups at 15 days of age, which gross neurological symptoms were evident in group D, showed that concentrations of GABA were decreased in C/P, whereas aspartate (Asp), glutamate (Glu) and DA were not affected compared to C values. One hour postinjection of PN x HCl, D pups showed decreased Glu in C/P and increased Asp in SN and at 3 hours postinjection, GABA was increased in SN. Since some synapses in C/P were postulated to be from GABAergic striatal interneurons, fewer of these synapses in conjunction with decreased GABA in C/P may result in ineffective inhibition of the circuitry of C/P in vitamin B-6 deficiency.