Effects of Age, Sex, and Brightness of Field on Open-Field Behaviors of Rats

Abstract

48 male and 48 female Holtzman rats, ages 50, 100, and 150 days, were tested in a black or white open field to determine the effect of varying brightness of the field upon ambulation and defecation scores. There were significant negative correlations between all ambulation and defecation scores, except for the 50-day-old animals. Ambulation scores decreased over trials for all animals; defecation scores remained the same. Trials did not interact with age, sex, or brightness on either measure. In both fields females crossed more squares than males at ages 100 and 150 days, but there were no sex differences in ambulation at age 50 days. Most notable was a sex difference as a function of brightness of field; whereas male scores did not differ, females ambulated significantly more and tended to defecate less in the white field. Results are described in terms of the need for standardization of the open field.

Sex differences in discriminating between cues predicting threat and safety

“…Previous studies have reported decreased, unaltered or increased anxiety-like behaviour in females tested in the open field, whereas the finding of increased locomotion in females is more consistent across studies (Aguilar et al, 2003, Baran et al, 2010, Gray and Lalljee, 1974, Lehmann et al, 1999, Seliger, 1977). There are several possible reasons for this discrepancy between studies, including the measures quantified to index fear behaviour, the conditions under which testing occurred, and the strain used (Prut & Belzung, 2003).…”

Abolition of sex-dependent effects of prenatal exposure to diethylstilbestrol on emotional behavior in estrogen receptor-α knockout mice

“…Therefore, the results in the present study are summarized as follows: (1) aWT female mice were less emotional than aWT male mice, (2) this sex difference was abolished by prenatal DES treatment as female mice became more emotional, whereas male mice became less emotional, and (3) prenatal DES treatment had no effect on the levels of emotionality in both sexes of aERKO mice. A number of studies in rats have also consistently shown that male rats are more emotional than female rats [13][14][15], as we found in WT control mice. Perinatal exposure to bisphenol A, an estrogenic endocrine disruptor, indeed abolished sex differences in OF behavior in rats [16], as we found in WT mice in the present study.…”

“…Bright light conditions, such that we used to illuminate the light side of the LDT apparatus in the present study, generally elicits strong emotional response in nocturnal rodents [12,13]. On the basis of this phenomenon, it is well accepted that two measurements in the light side of the LDT apparatus, that is, time spent and total activity, are negatively correlated with the levels of emotionality or anxiety so that higher numbers indicate lower emotionality or anxiety levels.…”

The effects of isolation rearing on open‐field behavior in male rats depends on developmental stages

“…Additionally, a decrease of peripheral crossings in Group IS26-40 in Experiment 1 indicate more immobility in a less phobic place. Because immobility or crouching is considered as an avoidance response to a phobic place such as the open field in which rats have no way out (Blanchard, Yudko, Dulloog, & Blanchard, 2001;Roth & Katz, 1979;Seliger, 1977), it is possible that juvenile isolation enhances avoiding response of rats to a phobic environment by increasing anxiety rather than influencing general activity. In fact, when peripheral crossings in Experiment 1 were analyzed every 5 min, Group IS26-40 revealed significantly lower peripheral crossings compared to Groups IS39-40 and P-40 only in the initial 10 min.…”

“…The age of rats at testing also was analyzed as a factor that might affect behavior. The open field used in the study was divided by an inner wall into two areas, a dim surrounding area (the peripheral alley) and a bright center square (the center field), based on the hypothesis that open-field behavior consists of two behavioral dimensions: general activity and exploration (Roth & Katz, 1979;Seliger, 1977). The number of crossings in the peripheral area can measure general activity of rats, and exploration (approaching response to a novel place) can be measured by the number of entries into the center area (Einon & Morgan, 1976;Hall et al, 1997b).…”