Effects of acute stress on the day of proestrus on sexual behavior and ovulation in female rats: Participation of the angiotensinergic system Márcio Vinícius Fagundes Donadio a,b , Aline Kunrath a , Kizzy Ludnila Corezola a , Celso Rodrigues Franci c , Janete A. Anselmo-Franci d , Aldo Bolten Lucion a , Gilberto Luiz Sanvitto a, ⁎ a Laboratório de Neuroendocrinologia do Comportamento, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil b Laboratório de Biofísica Celular e Inflamação, Departamento de Ciências Morfofisiológicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brasil c Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil d Laboratório de Neuroendocrinologia, Departamento de Fisiologia, Morfologia e Estomatologia, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil Received 23 May 2006; received in revised form 26 April 2007; accepted 2 May 2007 Abstract Physical or emotional stress can affect the female reproductive physiology and angiotensin II (Ang II) is a hormone that participates in the stress response and also in the control of reproductive hormones. The present study aimed at evaluating the effects of acute stress in the morning and afternoon of proestrus on sexual behavior and ovulation and the participation of Ang II in the stress-induced effects. Female rats with regular estrous cycles were used. Several different stress protocols were tested in the morning and in the afternoon of proestrus: restraint stress 10 min; restraint stress 1 h and ether stress, respectively. The participation of Ang II was evaluated by injecting Ang II receptor antagonists (losartan and PD123319) 15 min before stress. The lordosis quotient was recorded and the number of oocytes was counted. Plasma levels of luteinizing hormone, progesterone, prolactin and corticosterone were measured. All types of stress in the morning of proestrus induced a reduction in the number of oocytes. Restraint stress (1 h) in the afternoon of proestrus induced a significant reduction in the lordosis quotient. Peripheral and central losartan, but not PD123319, injections partly reverted the effects of stress on ovulation in the morning of proestrus. Acute stress in the morning of proestrus also reduced luteinizing hormone, progesterone and prolactin surges later on the same day. In conclusion, acute stress on the day of proestrus can affect female reproductive physiology. Moreover, the angiotensinergic system, through AT 1 receptors, participates in the effects of acute stress in the morning of proestrus. © 2007 Elsevier Inc. All rights reserved. Keywords: Stress; Ovulation; Sexual behavior; Female rats; Estrous cycle; Angiotensin II; LH; Progesterone; Prolactin 1. Introduction Reproductive functions such as luteinizing hormone (LH) secretion and sexual behavior can be affected by stressful experiences [1,2]. Stress activates the hypothalamic–pituitary– adrenocortical (HPA) axis and disrupts the hypothalamic– pituitary–gonadal (HPG) axis, leading to suppressive effects on female reproductive physiology and behavior [1,3]. The sup- pressive effect of stress on the HPG axis, especially in chronic stress models, is believed to be due primarily to the influence of elevated levels of corticotropin-releasing hormone (CRH) and glucocorticoids [4]. Women submitted to intense exercise, which is considered physiological stress, present many repro- ductive abnormalities including delayed menarche, amenorrhea and infertility [5]. Physiology & Behavior 92 (2007) 591 – 600 ⁎ Corresponding author. Universidade Federal do Rio Grande do Sul, Instituto de Ciências Básicas da Saúde, Departamento de Fisiologia, Laboratório de Neuroendocrinologia do Comportamento, Rua Sarmento Leite, 500, CEP 90050- 170, Porto Alegre, RS, Brazil. Tel.: +55 51 3316 3359; fax: +55 51 3316 3656. E-mail address: sanvitto@portoweb.com.br (G.L. Sanvitto). 0031-9384/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.physbeh.2007.05.005