Behavioural Brain Research 207 (2010) 429–433
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Behavioural Brain Research
journal homepage: www.elsevier.com/locate/bbr
Effect of acute stress on sexual behavior in female rats: Participation of the
central angiotensinergic system
Ana Lúcia Cecconello
, Charlis Raineki, Vanise Sebben, Aldo Bolten Lucion, Gilberto Luiz Sanvitto
Laboratório de Neuroendocrinologia do Comportamento, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde,
Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite 500, Porto Alegre, Rio Grande do Sul (RS) 90050-170, Brazil
Received 27 July 2009
Received in revised form 15 October 2009
Accepted 20 October 2009
Available online 29 October 2009
Stress might inﬂuence the reproductive behavior in females, and central angiotensin II (Ang II) is a peptide
that plays a role in stress response and in the modulation of sexual behavior. The medial amygdala (MeA),
an important structure that regulates this behavior, is strongly involved in stress response. The aim of
the present study was to evaluate the effect of acute restraint stress on the night of proestrus on sexual
receptivity in female rats and the participation of Ang II and MeA in this effect. Adult female Wistar rats
with regular estrous cycles were utilized. The acute stress protocol utilized was the restraint stress for
15 min on the night of proestrus. The participation of Ang II was evaluated by injecting Ang II and Ang
II receptor antagonists (losartan and PD12319) into the MeA. The lordosis quotient was recorded. The
stress or the microinjection of Ang II into the MeA signiﬁcantly reduced sexual behavior. The blockade
receptors in the MeA prevented the effect of stress and the effect of Ang II microinjection
into this nucleus on sexual receptivity. We concluded that acute restraint stress on the night of proestrus
reduces sexual behavior in rats, and this effect is mediated by both AT
receptors in the MeA.
© 2009 Elsevier B.V. All rights reserved.
Different stress paradigms, in general, induce a decreased sexual
behavior in female rats [18,58,59,63]. The effect of acute stress on
sexual receptivity may vary according to the time at which stress is
applied on the day of proestrus, phase of the estrous cycle in which
the female is receptive to the male .
One of the major stress hormones, Ang II, increases in the plasma
as well as in the central nervous system in response to stress stim-
ulation . Stress increases the density of Ang II binding sites in
the hypothalamic paraventricular nucleus and subfornical organ of
rats . Indeed, the Ang II receptor blockade completely abolishes
the HPA response to stress, strongly supporting that Ang II plays a
major role as stress hormone [3,4,51].
The medial nucleus of the amygdala (MeA), an important reg-
ulatory structure of sexual behavior in male and female rats
[6,10,15,16,47,48], is also involved in stress responses. Studies have
shown changes in dendritic spine density  and an increase in the
c-fos expression  in the MeA in rats exposed to different stress
paradigms. This nucleus expresses both Ang II receptors type AT
[7,8,10,57], and also contains Ang II . The microinjec-
Corresponding author. Tel.: +55 51 33083359; fax: +55 51 33083092.
E-mail address: firstname.lastname@example.org (A.L. Cecconello).
tion of this peptide into the ventricular system [14,25] or directly
into the MeA  promotes a reduction in sexual behavior in male
In the present study, we proposed to investigate the inﬂuence
of acute stress on the night of proestrus on the sexual behavior of
female rats, period in which they show greater sexual receptivity
. Considering that stress activates the central angiotensiner-
gic system , and that Ang II inhibits sexual behavior in males
[10,14,25], and also, that the MeA is involved in stress response
[17,32], regulates sexual behavior [6,47,48] and shows speciﬁc Ang
II binding sites [7,8,10,57], we proposed to analyze the participa-
tion of Ang II in the MeA as a mediator of the stress effect on sexual
behavior in female rats.
2. Material and methods
Adult female Wistar rats were obtained from the colony of the Universidade
Federal do Rio Grande do Sul (Porto Alegre, Brazil). Animals were housed in a
temperature-controlled room (22 ± 1
C) with a 12:12 h light-dark cycle (lights on at
0600 h) and free access to food (Rodent chow-Nutrilab, Colombo, Brazil) and water.
In all experiments vaginal smears were taken daily and only female rats with at
least 3 consecutive regular estrous cycles were used. All procedures and care of the
animals are in agreement with the National Institute of Health (NIH) Guide for the
Care and Use of Laboratory Animals and were approved by the Ethics Committee of
UFRGS—registration number of the project 2007841 (accredited with the National
Commission of Ethics in Research).
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