PII S0361-9230(00)00334-8
Permanent and transitory morphometric changes of
NADPH-diaphorase-containing neurons in the rat
visual cortex after early malnutrition
J. M. C. Borba,
1
M. S. Arau ´ jo,
1
C. W. Picanc ¸ o-Diniz,
2
R. Manha ˜ es-de-Castro
1
and R. C. A. Guedes
1
*
1
Laborato ´ rio de Fisiologia da Nutric ¸a ˜ o Naide Teodo ´ sio, Departamento de Nutric ¸a ˜ o, Universidade Federal de
Pernambuco, Recife, PE, Brazil; and
2
Laborato ´rio de Biofı´sica Celular, Departamento de Fisiologia, Centro de
Cie ˆ ncias Biolo ´ gicas, Universidade Federal do Para ´ , Bele ´ m, PA, Brazil
[Received 15 September 1999; Revised 31 March 2000; Accepted 19 June 2000]
ABSTRACT: We investigated the histochemical positivity to
NADPH-diaphorase, which reveals nitric oxide synthase activ-
ity, in area 17 of rats malnourished early in life, both in the
post-weaning period (group M1), and in adulthood after nutri-
tional recovering (group M2). Control pups (C1 and C2 groups)
received ad libitum after weaning the same diets as their moth-
ers. Rats of group M2 were nutritionally recovered by receiving
the control diet from post-natal day 42 until adulthood. Alde-
hyde-fixed sections (200-m thick) through area 17 were pro-
cessed for NADPH-diaphorase histochemistry following the
malic enzyme indirect method. The features of NADPH-diaph-
orase-containing neurons of area 17 of malnourished young
(M1) and adult (M2) rats were analyzed quantitatively in com-
parison to the matched groups C1 and C2. Permanent changes,
represented by increase in the density and dendritic field areas
of NADPH-diaphorase-positive cells, and transitory ones, rep-
resented by decreased values of soma areas, were observed in
area 17 of the M1 and M2 cases. However, some other features,
such as dendritic branch angle and number of dendrites per cell
in the gray matter, remained unchanged after malnutrition.
Thus, the findings indicate a possible relationship between
early malnutrition and alterations in nitric oxide synthase-con-
taining cells in the visual cortex. Physiological implications of
these data may be related to synaptic plasticity and refinement
of developmental brain circuits. © 2000 Elsevier Science Inc.
KEY WORDS: Nitric oxide synthase, Starvation, Development,
Plasticity, Area 17, Rat.
INTRODUCTION
The still substantial number of children affected by malnutrition in
certain parts of the world [41] has originated an impressive number
of studies aimed at clarifying the effects of early malnutrition on
the adult central nervous system. Depending on the period of
occurrence and degree of malnutrition, severe though not fully
documented consequences may occur during child development.
Several studies have shown in some detail the response of the
developing brain to nutritional deprivation. Brains of malnourished
subjects can present permanent and/or transitory changes in struc-
ture and function, which have been reported both in laboratory
animals (e.g., [39,40]) and in humans [26,35]. Different ap-
proaches have been used in order to understand to what extent such
nutritional disorders affect neuroanatomical [11,17,20,21,25,33,
34,47], biochemical [1,14,36,38,45,47] and electrophysiological
aspects of the brain [4,28,29,44]. It is now clear that such changes
are much more severe when malnutrition coincides with the so-
called “brain growth spurt”, which corresponds to the highest rate
of neurogenesis, gliogenesis and neuronal migration, in each cor-
tical area [20,39,40].
Nutritional deprivation during the brain growth spurt can pro-
mote different changes of metric features in malnourished subjects.
For example, a number of studies have demonstrated reduction of
the brain weight [17,22,28,29,54], and volume [7,39], as well as of
the thickness of the cerebral cortex [15,21]. In addition, increase in
the number of dendritic spines has been reported in these condi-
tions in visual cortical pyramidal neurons [17]. Reduction of the
thickness of dendritic processes, as well as of the number and
density of dendritic spines, have been reported in the frontal and
occipital cortices [49]. Structural changes also include increased
density of dendritic spines in the striatum and entorhinal cortex of
rats [11]. Reduced density of boutons in axon terminals, represent-
ing potential synaptic sites, as well as qualitative and quantitative
differences between dendritic metric features of the NADPH-
diaphorase (NADPH-d)-positive neurons have also been described
in adult, previously malnourished rats [42].
As previously emphasized [42], the study of NADPH-d histo-
chemical activity in perinatal malnourished brain deserves special
interest. NADPH-d has been characterized biochemically and im-
munochemically as a nitric oxide synthase [10,16,30,31,52,57,58]
(see also [59] for review). This enzyme is involved in the produc-
tion of nitric oxide, which is a diffusible gas that has been impli-
cated in synaptic plasticity during brain development and in the
refinement of neural circuits [9,24,31,51]. NADPH-d-positive cells
represent in the rat neocortex a peculiar population of neurons,
sparsely distributed in the deep half of the pallium at birth. By the
end of the second post-natal week, both the number and laminar
* Address for correspondence: Dr. Rubem C. A. Guedes, Universidade Federal de Pernambuco, Departamento de Nutric ¸a ´o, 50670-901 Recife, PE, Brazil.
Fax: +0055-81-2718473; E-mail: rguedes@npd.ufpe.br
Brain Research Bulletin, Vol. 53, No. 2, pp. 193–201, 2000
Copyright © 2000 Elsevier Science Inc.
Printed in the USA. All rights reserved
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