The administration of a relatively high dose of antidepressant drugs produces an increased neuronal firing rate of the lateral septal nucleus (LSN) in the rat and a decreased immobility in rats forced to swim. However, it is unknown whether a minimally effective low-dose 21-day treatment with the selective serotonin reuptake inhibitor, fluoxetine, while reducing immobility in the forced swim test, also increases the neuronal firing rate of the LSN in Wistar rats. The total time of immobility decreased with a daily injection of 0.5, 1.0 or 2.0 mg/kg of fluoxetine (p< 0.001), and the lowest dose increasing the latency to the first immobility period (p < 0.0001) was 1.0 mg/kg. Therefore, the action of the 21-day fluoxetine treatment (1.0 mg/kg) on the firing rate of LSN neurones was tested in another group of rats. A total amount of 78 single-unit extracellular recordings was taken from the LSN of eight control rats (n = 40) and eight fluoxetine treated rats (n = 38). The LSN firing rate in the fluoxetine group was double (18.3 ± 2.5 spikes per 10 s, p< 0.05) that in the control group (7.0 ± 0.9 spikes per 10 s), and the first order interval of firing proved to be significantly lower in the fluoxetine group compared to the control group (384.3 ± 22.3 and 639.7 ± 27.5 ms, respectively; p < 0.05). In conclusion, the increased neuronal firing rate of the LSN in the animals treated with a low dose of fluoxetine may be associated with an increased motivation to escape from the stressful situation that the forced swim represents.

Since allopregnanolone reduces the total time of immobility in rats submitted to the forced swimming test, we decided to explore whether this neuroactive steroid shares other antidepressant-like actions, such as increasing the neuronal firing rate in the lateral septal nucleus (LSN). In order to discard the influence of the oestrous cycle on immobility and on the firing rate of LSN neurons, all Wistar rats used in the study underwent ovariectomy before treatments. A group of rats received different doses of allopregnanolone (0.5, 1.0, 2.0 and 3.0mg/kg, i.p.) 1 hour before being forced to swim in order to identify the minimum effective dose diminishing immobility. None of the tested doses of allopregnanolone produced significant changes in motor activity in the open-field test. The minimum dose of allopregnanolone producing a significant reduction in the total time of immobility ( p<0.05) against the vehicle was 1.0mg/kg, while 2.0mg/kg and above also increased the latency to the first period of immobility ( p<0.05). The minimum effective dose of allopregnanolone reducing immobility in the forced swimming test (1.0mg/kg) significantly ( p <0.05) produced a higher (twofold) neuronal firing rate in LSN neurons, but did not produce any change in septofimbrial nucleus neurons, which fired at a rate similar to that of vehicle-treated rats. The pretreatment with the non-competitive GABA_A receptor antagonist, picrotoxin (1.0mg/kg), blocked the aforementioned actions of allopregnanolone on both immobility and LSN firing rate. In conclusion, allopregnanolone produces an antidepressant-like effect in the forced swimming test, associated with an increase in the LSN neuronal firing rate, seemingly mediated by the GABA_A receptor.

EspañolCon el objetivo de explorar las relaciones entre la autoeficacia académica y la ansiedad, como incidente crítico, el presente estudio descriptivo-correlacional incluyó una muestra de 310 estudiantes (183 mujeres y 127 hombres), quienes respondieron a la Escala de Autoeficacia en Conductas Académicas (EACA), la Escala de Ansiedad ZUNG y el Inventario de Ansiedad Estado-Rasgo (IDARE). La prueba de Pearson indicó una correlación positiva significativa entre las puntuaciones de autoeficacia percibida, deseable y alcanzable en EACA, pero una correlación negativa con el índice de mejora de la misma prueba; es decir, los puntajes de autoeficacia percibida, deseable y alcanzable se comportan de manera similar; pero, a medida en que los puntajes de estos tres indicadores disminuyen, la puntuación del índice de mejora es mayor. Por lo tanto, la autoeficacia percibida se tomó como el principal indicador de EACA, la cual se correlacionó inversamente con los puntajes de las escalas de ZUNG e IDARE; es decir, cuanto menor es la autoeficacia percibida mayor es el nivel de ansiedad. En un segundo análisis, un criterio arbitrario permitió definir tres rangos de puntuaciones en autoeficacia percibida: baja (puntuación 1-7.4), intermedia (puntuación 7.5-8.9) y alta (puntuación 9.0-10.0). Un ANOVA de dos vías indicó que los estudiantes, con niveles de autoeficacia percibida baja, obtuvieron los niveles de ansiedad más altos con la conocida tendencia del género femenino a desarrollar mayores puntajes de ansiedad. En conclusión, los estudiantes con baja autoeficacia percibida manifiestan ansiedad en el momento de la prueba. Permanece pendiente la exploración de una relación causa-efecto.EnglishWith the aim of exploring relationships between academic self-efficacy and anxiety, as critical incidents, this descriptive study included a sample of 310 students (183 women and 127 men). Volunteers responded to the Selfefficacy in Academic Behavior Scale (EACA), ZUNG anxiety scale and State-Trait Anxiety Inventory (STAI). A correlation analysis was performed between the different levels of perceived, desirable, achievable self-efficacy and an improvement index with anxiety indicators. A Pearson analysis indicated a moderate but significant positive correlation among perceived, desirable, and attainable self-efficacy scores in the EACA test, but a negative correlation among these three indicators and the same test’s improvement index. In other words, perceived, desirable, and attainable self-efficacy scores tabulated similarly, but as the scores of these three indicators rose, the score of the improvement index declined. Therefore, the perceived self-efficacy was taken as main indicator of EACA. The perceived self-efficacy correlated inversely with the scores obtained on ZUNG and STAI scales, i.e., as lower the perceived self-efficacy, the higher the level of anxiety. In second analyses, an arbitrary criterion allowed the establishment of three ranges of perceived self-efficacy scores into low (score 1-7.4), intermediate (score 7.5-8.9) and high (score 9.0-10.0). A two-way ANOVA indicated that students in the low range of perceived self-efficacy also scored the highest anxiety levels, with the well-known trend of feminine gender to express high levels of anxiety. In conclusion, students with low perceived self-efficacy are also anxious at the moment of the test, leaving for the future an exploration of a cause and effect relationship.