This is the first report of the effects of malnutrition during brain development on biocytin-labelled axon terminals and histochemical pattern of NADPH-diaphorase (NADPH-d)-containing neurons in area 17 of the adult rat. Wistar rats (n = 6) were submitted early in life (from gestation up to 42 days of age) to a multideficient diet (the 'regional basic diet' (RBD) of low-income human populations of north-east Brazil, containing only 8% protein). From day 43 up to adulthood (135-212 days), they were switched to a commercial laboratory chow diet (Purina do Brasil Ltda), with 22% protein. These animals were compared to control rats (n = 11), fed the laboratory chow diet until adulthood. The brains of four adult malnourished and five controls were processed according to the indirect method of the malic enzyme to reveal NADPH-d-containing neurons. Five other adult subjects (three controls and two malnourished) received iontophoretic injections of the tracer biocytin in area 17and were processed according to the glucose oxidase-DAB-nickel protocol in order to visualize axon terminals filled with biocytin. Three other control rats were processed for both techniques. In these last brains, no double-labelled cells could be found, suggesting that the NADPH-d-containing-neurons and the biocytin-labelled ones belong to different groups of cells, in area 17. The appendages of the NADPH-d-positive cells showed minor qualitative and quantitative differences between undernourished and control rats. The soma area of these cells was reduced in the white matter of malnourished rats, as compared to the controls (468.6 ± 54.3 μm(2); n = 4 and 515.4 ± 30.5 μm(2);n = 8, respectively; p < 0.05). The cell density (cells/mm(2)) was greater in the malnourished group than in the control, both at the grey matter (16.6 ± 4.4; n = 4 and 11.3 ± 4.3; n = 8, respectively; p < 0.05) and at the white matter (55.9 ± 15.7; n = 4 and 24.4 ± 8.5; n = 8; p < 0.005). The number of potential synaptic sites in the biocytin-labelled axon terminals was reduced as compared to the control (126 ± 33 boutons/mm, n = 32 and 160 ± 37; n = 30, respectively; p < 0.01). The results indicate that the rat area 17 is affected differently by early malnutrition, regarding biocytin-labelled axon terminals, on the one hand, and NADPH-d-containing neurons, on the other. Concerning these last cells, the data also suggest that they are less sensitive to the injury represented by early malnutrition.
Keywords: Area 17; Axon terminals; Biocytin; Malnutrition; NADPH-diaphorase cells; Rat.