The effects of early protein malnutrition and environmental stimulation on behavioral and biochemical parameters in rats.

Abstract

The present study investigated the effects of protein malnutrition and environmental stimulation on biochemical and behavioral parameters in rats. The concentrations of polyamines in the frontal cortex, striatum, and hippocampus, as well as plasma corticosterone levels, were measured. The exploratory behavior was analyzed using the elevated plus-maze (EPM) test. Rats received either 16% (well-nourished -W) or 6% (malnourished -M) protein diets and were divided into stimulated or non-stimulated groups. Malnutrition increased corticosterone levels and decreased plasma protein and anxiety. Non-stimulated rats tested in the EPM had increased corticosterone levels and decreased frontal cortex, striatum and hippocampus protein and polyamines contents. Stimulation decreased open arm entries in the EPM in M animals and increased closed arm entries in the W ones. Stimulation increased frequency and time spent in risk-assessment behaviors. These results suggest that both malnutrition and EPM testing are distressing situations, as indicated by increased corticosterone levels. These results are consistent with lower anxiety and/or higher impulsiveness in M animals.

Protective roles of selenium and zinc against postnatal protein‐undernutrition‐induced alterations in Ca2+‐homeostasis leading to cognitive deficits in Wistar rats

“…The suggested reasons for the impaired cognitive function in protein undernourished animals include stress, physical weakness due to poor nutrition and lack of sufficient protein components for normal neurodevelopment leading to cognitive and behavioral problem in animals (Yanai et al, 2004). Moreover, Sampaio et al (2008) reported that low protein diet increased the levels of plasma corticosterone; the increase in which has been linked to anxiety relief. Their finding confirmed our earlier report on elevated plus maze (EPM) cognitive function test that low protein diet reduces anxiety and/or impulsiveness (Alamy and Bengelloun, 2012) which has been associated with decreased in basal extracellular dopamine level.…”

Effects of early protein malnutrition and environmental stimulation on behavioral and biochemical parameters in rats submitted to the elevated plus-maze test

“…14,15,43 Although the exposition of the dams to a low protein diet can result in a stress condition during the lactation period and, thus, produce alterations in the maternal behavior in response to the pup's demands, previously reported results showed that these possible effects appears to be transient and restricted to the social behavior procedures, with no evident effects on experimental models of anxiety in rats. 7,15,16,18,19,30,39,40 Thus, it is suggested that possible alterations in the behavior of the animals nursed by malnourished dams did not influenced their behavior in the EPM. In contrast, it is suggested that this lower anxiety and/or higher impulsivity can be the result of deleterious effects of early protein malnutrition in the development and maturation of the structures involved in behavioral inhibition, such as the septum, the hippocampus, and the amygdala.…”

“…3,5 In this study, the stress caused by malnutrition in rats exposed to the EPM can be observed through the increased CORT levels in rats submitted to early protein malnutrition as compared with the well-nourished ones, suggesting an alteration of the organism's stress response as previously demonstrated. 7 It is also known that the individual experience, as the environmental stimulation, in the period of the CNS development, also alters the activity of the HPA axis. 53,54 However, in this study it was not possible to observe any significant statistical difference in CORT levels between stimulated and non-stimulated animals.…”

“…1,2 Studies in rats indicate that when the malnutrition is imposed during the prenatal period it can alter the development of the central nervous system (CNS), especially the plasticity of the hippocampus. [3][4][5] During the postnatal period it was shown that the protein malnutrition alters the levels of the glucocorticoid as well as the plasmatic corticosterone (CORT), 6,7 suggesting a modification in the response of the adrenocorticotropin to the stress. Protein malnutrition can cause a decrease on the number of glucocorticoid receptors in the hippocampus, 3,8,9 altering the sensibility of the hypothalamic-pituitary-adrenal axis (HPA) and consequently the response of the organism to the stress.…”

“…Protein malnutrition can cause a decrease on the number of glucocorticoid receptors in the hippocampus, 3,8,9 altering the sensibility of the hypothalamic-pituitary-adrenal axis (HPA) and consequently the response of the organism to the stress. 3,5,7 The CORT participates in the synthesis of the ornithine decarboxylase (ODC), being essential in the polyamines synthesis processes [ putrescine, spermine (SPM), and spermidine (SPD)]. [10][11][12][13] The polyamines can present changes in the anabolic/catabolic process during aversive stimulation, a phenomenon known as the polyamine response to stress.…”