Influence of Different Levels of Dietary Pyridoxine on Certain Parameters of Developing and Mature Brains in Rats

Abstract

The influence of different levels of dietary pyridoxine·HCl (1.2, 2.4, 4.8, 9.6, 19.2, 38.4, 76.8 and 153.6 mg/kg diet) fed to dams on certain parameters of developing and mature brain was studied in rats. Brain weights and alanine aminotransferase (ALAT) activities (initial and following in vitro addition of pyridoxal phosphate, PLP) were significantly reduced in brains of 12-day-old pups of dams fed the lowest level of pyridoxine compared to other treatments; in vitro addition of PLP significantly stimulated the activities of glutamic acid decarboxylase (GAD) and ALAT. Vitamin B-6 concentrations in brain were higher for 2-day-old pups of dams fed 38.4 or 76.8 mg vitamin/kg diet and for 12-day-old pups of dams fed 2.4 to 153.6 mg compared to the 1.2 mg groups; at weaning, values were greater in groups fed 76.8 or 153.6 mg compared to the 2.4 mg group. Similarly, the vitamin content in the mature brain of the dams was greater for 76.8 or 153.6 mg groups compared to the 1.2 mg group. As brain developed during the suckling period, the content of vitamin B-6 and protein increased in all groups, except the 1.2 mg group in which values remained the same. The vitamin and protein content in brain had not reached chemical maturity at weaning as evidenced by greater concentrations of each in brains of dams as compared with values for 21-day-old progeny. As brain developed, ALAT activity increased about 30 times from age 2 to 21 days when activities were similar to those observed in mature brains of dams. Activity of GAD in brain increased about four times from age 12 to 21 days.