Resumo

Maternal thiamine deficiency causes changes in cellular energy metabolism that can interfere with offspring brain development. The purpose of the present study was to investigate the effects of thiamine restriction, during lactation, on offspring neurochemistry and cognitive parameters. Male young (31 days old) and adult (75 days old) rats, from control and restricted mothers, were submitted to spatial learning and memory assessment using a Morris Water Maze. GABAergic and glutamatergic parameters were measured in thalamus, prefrontal cortex (PFC) and hippocampus by high performance liquid chromatography (HPLC). Twenty-nine rats – 11 from 3 control and 18 from 3 restricted mothers – were submitted to spatial cognitive assessment for about 15 days. One day after, it was followed by biochemical studies. The second experiment had a similar experimental design, except that the male rats had a 45 day recovery period and were tested at the age of 75 days (adult group). Twenty-eight rats – 11 from 3 control and 17 from 3 restricted mothers – were submitted to the same sequence of procedures. In young rats, thiamine restriction significantly hindered body weight gain and learning speed; however, it did not affect the brain weight, GABA and glutamate parameters in any of the brain assessed areas. In adult rats the body weight gain was significantly hampered by thiamine restriction, while brain weight and spatial task were not affected. Thiamine restriction induced a significant decrease on glutamate concentration in all analyzed brain regions of adult animals [thalamus: F(1,26) = 37.98, p = 0.0001; hippocampus: F(1,26) = 13.35, p = 0.001; PFC: F(1,26) = 12.74, p = 0.001]. However, a significant reduction in GABA level was observed in thalamus but not in hippocampus or in PFC of adult rats [thalamus: F(1,26) = 11.38, p = 0.002; hippocampus: F(1,26) = 1.25, p = 0.27; PFC: F(1,26) = 0.24, p = 0.62]. One possible explanation for these findings is that an adjustment of the inhibitory (GABAergic) and stimulatory (glutamatergic) neuromodulation systems occurs, in order to reverse the behavioral deficits detected in young rats but not in adult ones. The present data show, for the first time, that maternal thiamine restriction during lactation induces cognitive impairments and neurochemical changes in offspring, corroborating the important role of thiamine in brain development.