El Amaranto como Fuente de Reforzamiento: Un Estudio con Roedores / Amaranth as Reinforcement Source: A Rodent Study

Resumen: El presente estudio evalúa el amaranto como una alternativa a los reforzadores que se utilizan en la actualidad en los laboratorios experimentales con roedores. Se compararon diversos elementos como la preferencia de consumo, la motivación y el valor reforzante entre tres tipos de alimentos (dos tipos de pellets y amaranto) mediante cuatro experimentos con laberinto radial y consumo libre en 11 ratas de la cepa Wistar. Los resultados muestran que el amaranto tiene un alto valor reforzante ya que, se observó preferencia por su consumo comparado con los demás alimentos. Se propone al amaranto como una buena alternativa para usarse como reforzador con varias ventajas como la preferencia de consumo, su valor reforzante, su fácil accesibilidad en el país y que es más económico que los pellets importados.

Abstract: This study evaluates amaranth as an alternative to reinforcers which are currently used in experimental laboratories with rodents. We compared some elements such as consumer preference, motivation and reinforcing value of three types of food (two types of pellets and amaranth) through four experiments with free radial maze and free consumption in 11 Wistar rats. The results show that amaranth has a high reinforcing value. Also, there was a preference for amaranth consumption compared with the other two reinforcers. Amaranth is proposed as a good alternative for use as a reinforcer with several advantages such as consumer preference, its reinforcing value, accessibility in the country and that it is cheaper than the usual pellets.

The Effect of BF-7 on the Ischemia-induced Learning and Memory Deficits / 대한해부학회지

Abnormal blood supply to brain, such as ischemia induce neuronal damages, possibly leading to dementia. Such damages should be attenuated by neuroprotective materials which make neurons tolerable against limited blood supply or reinforce of blood. For the animal study, transient middle cerebral artery occlusion was operated with SD rat. To check whether BF-7 attenuated the ischemic damage, BF-7 (10 mg/kg) was oral treated for 7 days once a day. To evaluate the learning and memory of the rat, 8-arm maze test was conducted. For clinical study, Rey Complex Figure Test (RCFT) was used with control group (32 person), 200 mg treated group (33 person) and 400 mg treated group (34 person). Treatment of BF-7 greatly reduced the infarct size. Also the neuronal damages in the hippocampus were significantly diminished. Furthermore, The memory impairment by ischemia was recovered. The clinical test showed that BF-7 greatly enhanced the brain function recognizing and memorizing complex two dimensional figures. Our results implicated that BF-7 plays a positive roles on protecting brain and enhancing brain unction clinically.

El estrés deteriora la memoria de trabajo espacial en ratas hembra / Stress impairs spatial working memory in female rats

Se exploró la modulación del deterioro de la memoria de trabajo espacial producida por estrés psicológico en ratas hembra Sprague-Dawley, de acuerdo a la hipótesis de Diamond et al. (1996). Los sujetos fueron entrenados en tareas de memoria de trabajo y de referencia en laberinto radial de ocho brazos. Alcanzado el criterio en memoria de trabajo, la demora entre el recorrido informativo y el de prueba -15´´- se incrementó sucesivamente a 5´ y 4 horas, manteniéndose los sujetos en un ambiente familiar. Se los expuso luego a un estresor psicológico -cambio a ambiente no familiar con olor de predador- durante la demora de 4 horas. Los resultados mostraron un deterioro inicial en el rendimiento en memoria de trabajo -pero no en memoria referencial- con la introducción del estresor, efecto que se ve atenuado a través de sucesivas exposiciones, como producto de la habituación al ambiente no familiar.

Spatial working memory impairment by psychological stress in Sprague-Dawley female rats was studied, according to Diamond et al hypothesis (1996). Subjects were trained on reference and working memory tasks in an 8-arm radial maze. Once criterion was reached, delay phase was increased first day, from 15 sec to 5 min, and the second day, from 5 min to 4 hr, with subjects remaining in their familiar environment. Subjects were exposured to a psychological stressor -change to a novel environment, with animals placed in restraint, predator scented cages- during the 4 hr delay period. Working memory errors -but not reference memory errors- significantly increased at first days, under stress condition. Working memory impairment was attenuated as a result of habituation to unfamiliar environment in subsequent four days,

Association of Schizophrenia with Pathological Aging : A Behavioral and Histological Study Using Animal Model

OBJECTIVES: Phencyclidine(PCP) or PCP-like substances such as ketamine have been know to rekindle the cognitive dysfunction in schizophrenia. The aims of this study were to identify whether PCP-like substances can produce cognitive deficit in schizophrenia, to discuss relation with aging process, and finally to speculate underlying neurochemical mecha-nisms by various drug responses. METHODS: In experiment I, radial maze tests were done in 24 Sprague-Dawley rats for 3 days to get baseline data. Being divided into 4 groups(6 rats respectively) of normal aged, normal adult controls, atropine-treated and ketamine-treated, the radial maze tests were repeated on every week for 6 weeks, and then the rats were sacrificed by intracardiac perfusion with phosphate-buffered 10% formaldehyde solution for histology. The brain specimen was stained with hematoxylin-eosin to count cells in the prefrontal cortex and hippocampus. In experiment II, radial maze tests were done for 48 rats before any drug treatment and only after ketamine administration. Thereafter, haloperidol, bromocriptine, clonidine, nimodipine, tacrine, valproic acid, naloxone and fluoxetine were intramuscularly injected on every other day in addition to ketamine. Radial maze tests were repeated on every week for 6 weeks, and then rats were prepared by the same procedure for histology. RESULTS: 1) Reaction times of radial maze tests of atropine-treated rats were significantly prolonged than those of normal aged(p<0.05) or normal adult controls(p<0.05). Cell numbers of prefrontal cortex & hippocampus in ketamine-treated rats were significantly reduced than those in normal aged(p<0.05) or normal adult controls(p<0.005). 2) Reduced cell numbers by ketamine became significantly raised by tacrine administration in prefrontal cortex $ hippocampus(p<0.05), while there were no significant changes on radial maze test. Cell numbers also tended to be raised by nimodipine, fluoxetine and haloperidol administration. CONCLUSIONS: In conclusion, the visuospatial memory disorders in ketamine-induced psychotic rats might be partly associated with aging process. Furthermore, the responses to the various drugs suggested cholinergic system might have an important role in the neurochemical mechanism of the cognitive dysfunction in ketamine-induced psychosis. Otherwise, calcium metabolism as well as serotonergic and dopaminergic systems seemed to be possibly related.