Relative luminosity in the plus maze upon the exploratory behaviour of female Wistar rats

Abstract

Animal models have played an important role in furthering our understanding of complex biological basis and mechanisms underlying the pathogenesis of human anxiety. They have also contributed to the provision of preclinical models that enable the discovery and screening of new potential therapeutical drugs 1 . Moreover, animal models of anxiety have been considered as an invaluable approach, since animals display similar autonomic and behavioral reactions during anxiety states 2,3,4,5 . The present research chose on one of the most popularly used animal models in the study of anxiety-related behaviors 6 -the Elevated Plus-Maze (EPM). Briefly, the EPM is used as a test of anxiety based on the exploratory behavior of rodents. Its exploratory environment is constituted by four elevated arms, with two opposed open (unprotected spaces) and two other opposed enclosed arms (spaces protected by lateral walls), arranged in a cross-like shape. The open arms are considered regions of the maze endowed with stressful-and fear-inductor properties, because rats exposed to them display increased corticosterone release, as well as fear-related behaviors, when compared to those exposed in the enclosed arms 7 . In this sense, the conflict between the approach and the avoidance of regions with more or less aversive properties underlies the exploratory behavior of animals in the EPM. In fact, this conflict has been considered analogous to human anxiety considering that many anxiety disorders express this insidious avoidance behavior of a feared object or situation ) e foram testadas no LEC 10 A/F ∆Lux ou LEC 96 A/F ∆Lux . Resultados: A análise de regressão múltipla indicou que o A/F ∆Lux está negativamente associado com a % de entrada no braço aberto e % de tempo no braço aberto, sugerindo que no aumento do A/F ∆Lux , a exploração do braço aberto diminui. A fase do CE não influenciou a exploração do braço aberto no LEC. A ansiólise induzida pelo MDZ foi demonstrada no 96 LEC A/F ∆Lux em todas as fases do CE. Discussão: Estes resultados sugerem a importância do A/F ∆Lux para estabelecer a preferência da exploração do LEC e preservar a validade do LEC.Palavras-chave: ciclo estral, ratas Wistar, ansiedade, medo, labirinto elevado em cruz, luminosidade.

Effect of Estrous Cycle on Behavior of Females in Rodent Tests of Anxiety

“…Once the estrous cycle is taken into account, the picture starts to become less clear. In rats, some investigators report reduced anxiety levels (i.e., a more time spent in the open arms of the maze) in proestrus/estrus compared to diestrus ( 16 – 18 , 40 , 64 – 70 ) whereas others fail to see estrous cycle-linked effects at all ( 16 , 19 , 61 , 71 – 73 ). However, not all workers compare all stages of the cycle and in some cases results from two stages of the cycle have been pooled, which makes direct comparison between studies difficult.…”

“…In males, many factors have been identified that can influence responding and potentially lead to inconsistencies between results from different laboratories due to methodological differences. The importance of recognizing and carefully controlling testing conditions, particularly light level, has been highlighted ( 73 , 77 , 78 ). The age of the rat, circadian phase and light illumination level during testing have all been reported to influence the behavior of males ( 77 , 79 – 84 ) but see ( 85 ) for an opposing view.…”

Prenatal exposure to fluoxetine modulates emotionality and aversive memory in male and female rat offspring

“…Thus, we believe that the effects on the locomotion of females may have been related to the natural oscillation of sexual hormones, although we do not exclude the increased anxiety level to some extent, because of the novelty of the environment. For instance, female rats tend to exhibit greater locomotion in novel environments when compared to males in tests such as the open field and EPM (Johnston et al , 1991; Fernandes et al , 1999; Simpson et al , 2012; Sakae et al , 2015). Although we did not examine, in this study, the modulation of ovarian hormones and the control of the estrous cycle, for example.…”

Avaliação de respostas defensivas associadas ao pânico em ratas: perfil da ativação serotonérgica no núcleo dorsal da rafe e substância cinzenta periaquedutal

“…Em revisão recente, Lovick e Zangrossi (2021) abordaram com mais detalhes essa questão. Por exemplo, no LCE alguns trabalhos mostram não haver diferenças entre as fases do ciclo (FERNÁNDEZ-GUASTI et al, 1999;MOLINA-HERNÁNDEZ et al, 2013;NIN et al, 2012;SAKAE et al, 2015;SANTOS et al, 2014;SCHOLL et al, 2019), É digno de nota que em nosso estudo, células serotonérgicas não foram ativadas pelo desafio de hipóxia. Estudos realizados em machos também mostram um nível muito baixo, ou mesmo a ausência de expressão de c-Fos em células serotonérgicas de alguns subnúcleos do NDR após diferentes desafios estressantes (BARATTA et al, 2018;LOPES et al, 2016;ROCHE et al, 2003;SPANNUTH et al, 2011;VILELA-COSTA et al, 2019).…”