Estrous cycle stage influences on neuronal responsiveness to repeated anxiogenic stress in female rats

Autor(es)

Devall, Adam J. ^[1] ; Santos, Julia M. ^[1] ; Lovick, Thelma A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Birmingham, Sch Clin & Expt Med, Birmingham B15 2TT, W Midlands - England

• Tipo de documento: Artigo Científico
• Fonte: Behavioural Brain Research; v. 225, n. 1, p. 334-340, NOV 20 2011.
• Citações Web of Science: 8

Resumo

Experiments were carried out to investigate (i) whether estrous cycle stage influences nociceptive responsiveness to anxiogenic stress and (ii) whether prior experience of the stressor modifies the response. Exposure to mild anxiogenic vibration stress evoked hyperalgesia, reflected by a decrease in tail flick latency, only in animals in the late diestrus phase. Stress evoked hyperalgesia in late diestrus regardless of whether the rat was experiencing the stress for the first time or had been exposed to the stress previously, when in another cycle stage. Whilst the behavioral response to stress appeared to be determined exclusively by estrous cycle stage, the stress-evoked pattern of Fos expression in the periaqueductal grey matter (PAG) depended not only on cycle stage but also on whether the rat had previous experience of the stress. First exposure to stress in late diestrus evoked a 50% decrease in Fos expression compared to non-stressed controls, particularly in the lateral and dorsolateral sectors of the rostral PAG. In contrast, in experienced rats in late diestrus the pattern of Fos expression increased up to 4-fold, particularly in the ventral half of the caudal PAG but also in the lateral and dorsolateral parts. At other cycle stages Fos expression was not changed except for an increase in rats in proestrus. The results suggest that in females, changes in gonadal hormone levels during the estrous cycle impact significantly on the processing of fear-inducing stimuli by the PAG. These hormonal influences may also influence how the PAG responds to a subsequent anxiogenic challenge. (C) 2011 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 08/11408-2 - Avaliação comportamental, neuroquímica e imunohistoquímica do papel funcional de mecanismos serotoninérgicos da substância cinzenta periaquedutal dorsal e do núcleo dorsal da rafe em machos e fêmeas, em diferentes fases do ciclo estral.
• Beneficiário: Julia Maria dos Santos
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado