Raúl Angel Gómez

SHUTTLE-BOX DEFICITS INDUCED BY CHRONIC VARIABLE STRESS : REVERSAL BY IMIPRAMINE ADMINISTRATION

Escape performance in a shuttle-box task was evaluated in rats chronically exposed to a series of unpredictable stressors either during 14 or 7 consecutive days. Failure in escape responses was observed when animals were subjected to both regimes of variable aversive situations. The association between chronic exposure to unpredictable stressors with imipramine resulted in a significant reversal of escape deficits. Furthermore, animals submitted to repeated immobilization sessions during 7 days presented similar escape response to control rats. A possible involvement of beta-adrenergic sites on this behavioral response is discussed.

Gangliosides improve synaptic transmission in dentate gyrus of hippocampal rat slices

The effect of perfusion with gangliosides (1 x 10(-6) M) on the response evoked in the granule cell layer of dentate gyrus by stimulation of perforant path in hippocampal rat slices was studied. Gangliosides induced both a decrease in the frequency threshold of stimulation necessary to generate long-term potentiation (LTP) and greater potentiation than under control conditions. It is proposed that gangliosides improve the mechanisms responsible for synaptic plasticity which generate LTP.

Long-term potentiation-induced synaptic changes in hippocampal dentate gyrus of rats with an inborn low or high learning capacity

Structural changes induced by high frequency (HF) stimulation on granule cells of the hippocampal dentate gyrus of rats with inborn high (HP) and low (LP) learning capacity was examined in this study. Two types of axodendritic synapses were processed morphometrically; the axonal bouton on dendritic shafts and those making contact through dendritic spines. The occurrence of granule cell spine synapses on LP rats before tetanus is less than the one in control animals. However, after long-term potentiation (LTP) produced by HF stimulation the number of spine synapses decreased, as happened in the control rats. Moreover, the number of granule cells shaft synapses counted on LP rats, before tetanus is less than the one on control rats, and after LTP this number increased greatly. There was no change in the number of granule cell shaft synapses in HP rats before and after LTP. LP rats which did not show LTP in spite of HF stimulation did not show changes in the number of spine and shaft synapses. From these results we can conclude that: (1) the great hippocampal synaptic plasticity observed in HP rats compared to LP rats can be attributed, at least in part, to the increased number of spine and shaft synapses observed in HP rats; (2) the minor number of spine and shaft synapses in LP rats may account for the impossibility to obtain LTP after HF stimulation in these animals.

Effect of acute ethanol exposure during pregnancy on dentate gyrus synaptic plasticity in 45-day-old rats

Pregnant Wistar rats were treated during the eighth day of gestation (GD8) with two IP injections, spaced by an interval of 4 h, of either ethanol (2.9 g/kg in saline solution) or saline. At 45 days of age, rats prenatally exposed to alcohol showed an improved hippocampal synaptic plasticity in granule cells layer of dentate gyrus. This was assessed measuring the threshold to generate long-term potentiation (LTP) on hippocampal slices. We propose that this result might account for the good performance in some learning tasks observed in animals prenatally exposed to alcohol during short periods.

Estudio preliminar de los determinantes cognitivos que influyen en los jóvenes argentinos para realizar un consumo intensivo de alcohol, o binge drinking*

Resumen Introduccion El patron de consumo de alcohol que realizan actualmente los jovenes y adolescentes, caracterizado por ingerir cantidades elevadas, durante pocas horas y varios dias a la semana (binge drinking, consumo concentrado o consumo en atracon), es una realidad que comparten muchos paises, entre los que se incluyen Espana y Argentina. Objetivo Describir los determinantes cognitivos del comportamiento de consumo intensivo de alcohol (binge drinking), en sujetos de 16 a 25 anos en Argentina. Metodo Se uso una encuesta construida ad hoc para evaluar los determinantes cognitivos de la conducta de consumo intensivo de alcohol, segun las directrices de I. Ajzen. Resultados Existen diferencias estadisticamente significativas entre el grupo de consumidores intensivos y el que no alcanza este nivel de consumo, en relacion con las creencias conductuales y las creencias de control. Ambos grupos coinciden en que el consumo es perjudicial e inseguro; no hay diferencias en relacion con las creencias normativas. Conclusiones La interaccion entre los factores actitudinales, motivacionales y de control comportamental es compleja. Es preciso dar mayor sensibilidad a los instrumentos utilizados y realizar un analisis mas detallado sobre las consecuencias a corto, medio y largo plazo que genera un consumo intensivo de alcohol y el papel de este como reforzador, positivo o negativo.INTRODUCTION The current alcohol consumption pattern among youngsters and adolescents, characterized by heavy drinking during a few hours, several days a week, or binge drinking (binge drinking, concentrated drinking or long-gulp drinking) is a reality in many countries, including Spain and Argentina. OBJECTIVE To describe cognitive determinants in the behavior regarding excessive alcohol consumption (binge drinking) in 16-25 year subjects in Argentina. METHODOLOGY An ad hoc survey was conducted to assess cognitive determinants influencing heavy alcohol consumption, according to I. Ajzens guidelines. RESULTS There are significant statistic differences between the group of heavy drinkers and the group that does not reach such level of consumption in relation to behavioral beliefs, and control beliefs. Both groups recognized consumption is noxious and not safe; no differences were observed concerning normative beliefs. CONCLUSIONS There is a complex interaction mong attitudinal factors, motivational and behavior control factors. Instruments require greater sensitivity and further in-depth analysis is required regardomg short, middle and long consequences generated by binge drinking and its role as a positive or negative reinforment.