ABSTRACT
The purpose of this work was to investigate the influence of energy restriction and vitamin E supplementation on memory, learning, anxiety and spontaneous locomotion in adult rats. Three-month-old male Wistar rats were grouped according to diet: Control (AIN 93-M; n=18), Supplemented (AIN 93-M + 1425 IU all-rac-alpha-tocopheryl acetate/kg diet; n=22) and Restricted (AIN 93-M with 30% reduction in carbohydrate energy; n=23). Sixteen weeks after, the passive avoidance (PA), elevated plus-maze (EPM) and open field (OF) tests were applied. In the EPM test, the behavioral profile of the supplemented group was characterized by a lower frequency of entries into the open arms (P < 0,026), whereas the restricted group showed a lower frequency of head dipping (P < 0,003). The ratio between the time span of the shocks and the number of attempts were larger for the supplemented than for the non-supplemented animals (P = 0,0474), thus suggesting a delay in learning in the PA test. Taken together, these results suggest that a long-term combination of carbohydrate energy restriction in rats should not cause negative behavioral alterations. Compared with vitamin E supplementation, the restricted diet performed equally or better in rats as an alternate antioxidant diet.
Subject(s)
Behavior, Animal/drug effects , Diet, Carbohydrate-Restricted , Dietary Supplements , alpha-Tocopherol/administration & dosage , Animals , Locomotion/drug effects , Male , Maze Learning/drug effects , Memory/drug effects , Rats , Rats, Wistar , alpha-Tocopherol/pharmacologyABSTRACT
The purpose of this work was to investigate the influence of energy restriction and vitamin E supplementation on memory, learning, anxiety and spontaneous locomotion in adult rats. Three-month old male Wistar rats were grouped according to diet: Control (AIN 93-M; n=18), Supplemented (AIN 93-M + 1425 IU all-rac-alph-tocopheryl acetate/kg diet; n=22) and Restricted (AIN 93-M with 30 percent reduction in carbohydrate energy; n=23). Sixteen weeks after, the passive avoidance (PA), elevated plus-maze (EPM) and open field (OF) tests were applied. In the EPM test, the behavioral profile of the supplemented group was characterized by a lower frequency of entries into the open arms (P < 0,026), whereas the restricted group showed a lower frequency of head dipping (P < 0,003). The ratio between the time span of the shocks and the number of attempts were larger for the supplemented than for the non-supplemented animals (P = 0,0474), thus suggesting a delay in learning in the PA test. Taken together, these results suggest that a long-term combination of carbohydrate energy restriction in rats should not cause negative behavioral alterations. Compared with vitamin E supplementation, the restricted diet performed equally or better in rats as an alternate antioxidant diet.
Se investigó la influencia de la restricción energética en comparación a la suplementación con vitamina E en la memoria, aprendizaje, ansiedad y locomoción espontánea en ratas adultas. Machos Wistar de tres meses de edad fueron agrupados de acuerdo a las dietas: Control (AIN 93-M, n=18), Suplementados (AIN 93-M + 1425 UI all-rac-alfa-tocoferil acetato /kg de dieta; n=22) y Restrictos (AIN 93-M con 30 por ciento de restricción energética en los carbohidratos; n=23). Dieciséis semanas después, fueron aplicadas las pruebas de esquiva pasiva (PA), laberinto elevado en cruz (EPM) y de campo abierto (OF). En la prueba de EPM, el grupo suplementado mostró una menor frecuencia de entradas en los corredores abiertos (P < 0,026), mientras el grupo restricto registró menor frecuencia de bajadas de cabeza (P = 0,003). La razón entre la duración de los choques y el número de intentos fue superior para el grupo suplementado, que para los no suplementados (P = 0,0474), lo cual sugiere un leve perjuicio en el aprendizaje de los suplementados, según la prueba de PA. Tomados en conjunto, estos resultados sugieren que la restricción crónica en energía de carbohidratos no provoca alteraciones negativas en el comportamiento de ratas adultas y que sus beneficios pueden superar los obtenidos al suplementar la dieta patrón con vitamina E, como opción de dieta antioxidante.
Subject(s)
Animals , Rats , Antioxidants/therapeutic use , Behavior/radiation effects , Diet/adverse effects , Protein-Energy Malnutrition , Vitamin EABSTRACT
Electrical or chemical stimulation of the inferior colliculus (IC) induces fear-like behaviors. More recently, consistent evidence has shown that electrical stimulation of the central nucleus of the IC supports Pavlovian conditioning and latent inhibition (LI). LI is characterized by retardation in conditioning and also by an impaired ability to ignore irrelevant stimuli, after a non-reinforced pre-exposure to the conditioned stimulus. LI has been proposed as a behavioral model of cognitive abnormalities seen in schizophrenia. The aim of the present study was to determine whether dopaminergic mechanisms in the IC are involved in LI of the conditioned emotional response (CER). To induce LI, a group of rats was pre-exposed (PE) to six tones in two sessions, while rats that were not pre-exposed (NPE) had two sessions without tone presentations. The conditioning consisted of two tone presentations to the animal, followed immediately by a foot shock. PE and NPE rats received IC microinjections of physiological saline, the dopaminergic agonist apomorphine (9.0 microg/0.5 microL/side), or the dopaminergic antagonist haloperidol (0.5 microg/0.5 microL/side) before both pre-exposure and conditioning. During the test, the PE rats that received saline or haloperidol had a lower suppression of the licking response compared to NPE rats that received vehicle or haloperidol, indicating that latent inhibition was induced. There was no significant difference in the suppression ratio in rats that received apomorphine injections into the IC, indicating reduced latent inhibition. These results suggest that dopamine-mediated mechanisms of the IC are involved in the development of LI.
