Research reportSex differences in the acute ethanol effects on object recognition memory: influence of estrous cyclePaiva-Santos, Murilo A.a; Leão, Anderson H.F.F.a; Kurita, João P.F.a; Becegato, Marcela S.a; Lima, Alvaro C.a; Bioni, Vinicius S.a; Meurer, Ywlliane S.R.b; Cunha, Débora M.G.a; Medeiros, André M.c; Silva, Regina H.a Author Information aDepartment of Pharmacology, Universidade Federal de São Paulo, São Paulo bMemory and Cognition Laboratory, Department of Psychology, Universidade Federal da Paraíba, João Pessoa cDepartment of Health Sciences, Center of Health and Biological Sciences, Universidade Federal Rural do Semi-Árido, Mossoró, Brazil Received 17 June 2021 Accepted as revised 29 March 2022 Correspondence to Regina H. Silva, PhD, Department of Pharmacology, Universidade Federal de São Paulo, Rua Botucatu, 862, Edifício Leal Prado, 1º andar, CEP 04023062, São Paulo, Brazil, E-mail: [email protected] Behavioural Pharmacology: April 29, 2022 - Volume - Issue - 10.1097/FBP.0000000000000680 doi: 10.1097/FBP.0000000000000680 Buy PAP Metrics Abstract Effects of acute ethanol (EtOH) on memory depend on several factors, including type of behavioral task. Sex differences in EtOH effects have been reported in humans and animals, and recognition memory can be influenced by circulating sex hormones. The aim of this study was to investigate the influence of sex and estrous cycle in the acute effects of EtOH on novel object recognition memory in rats. Male and female Wistar rats were part of one of the groups: control, 0.6-g/kg EtOH and 1.8-g/kg EtOH (administered intraperitoneally before the training session). The estrous cycle was evaluated by vaginal smear. The task was conducted in an open field arena. During training, animals were exposed to two identical objects, and test sessions were performed 1 h (short-term) and 24 h (long-term) later. One of the objects was changed in each test. Increased novel object exploration was shown by male and female controls in the short- and long-term tests, respectively. In the short-term test, females did not show preference for the novel object, and EtOH 1.8 g/kg impaired performance in males. In the long-term test, both sexes showed object discrimination, and 1.8-g/kg EtOH reduced preference for the new object in male rats. The phase of the cycle, the performance on proestrus was worse compared with other phases, and EtOH failed to impair performance mainly on estrous. In conclusion, while male rats displayed ethanol-induced recognition memory deficit, female rats were unaffected by EtOH impairing effects. In addition, the performance of female rats was influenced by the estrous cycle phases. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.