Association Between Estrus Cycle-Related Changes in Respiration and Estrus Cycle-Related Aggression in Outbred Female Wistar Rats

Abstract

Premenstrual dysphoric disorder is characterized by irritability surfacing during the luteal phase of the menstrual cycle, and disappearing shortly after the onset of menstruation. Although the cardinal symptoms of premenstrual dysphoria are different from those of panic disorder, the two conditions share a number of traits indicating that they both may be associated with abnormalities in the regulation of respiration. Both subjects with panic disorder and subjects with premenstrual dysphoria are hence reported to display enhanced respiratory variability, and to experience anxiety when exposed to CO 2 . In the present study, the possible influence of the estrus cycle on respiratory parameters in outbred female rats of the Wistar strain was investigated. Before being tested with respect to respiration, the rats were subdivided into two groups: those displaying estrus cycle-related variation in aggression, as evaluated using the resident intruder paradigm, and those not showing aggression throughout the cycle. Whereas the former group was found to display higher respiratory rate during the diestrus phase than during the proestrus/estrus phase, no cycle-related variation in respiration was observed in animals not showing cycle-related variation in aggression. The results support previous studies indicating that the estrus cycle exerts an influence on respiration, and suggest that rats prone to cycle-related aggression are more sensitive also to the influence of hormonal cyclicity on respiration. The possible bearing of these findings for the aberration in respiration displayed by subjects with premenstrual dysphoria is discussed.

Plasticity of GABAA receptor subunit expression during the oestrous cycle of the rat: implications for premenstrual syndrome in women

“…Rodents too may be similarly affected. Increased levels of anxiety and aggression have been detected in rats during dioestrus, when plasma progesterone concentrations rise to reach peak levels similar to those that occur during the luteal phase in women, before falling to almost undetectable levels (McLaughlan et al 1987;Watanabe et al 1990;Mora et al 1996;Olsson et al 2003). Surprisingly, these findings were not replicated in mice, in which increased levels of anxiety were reported during oestrus rather than dioestrus (Maguire et al 2005).…”

“…During the menstrual cycle, plasma levels of progesterone and hence ALLO are lowest during the follicular phase, when symptoms are absent (Bäckström et al 2003). In the rat too, anxiety levels are low during proestrus (Olsson et al 2003) when plasma progesterone is at its lowest level, prior to the preovulatory surge (Butcher et al 1974; Watanabe et al 1990). This apparently paradoxical situation may be resolved by recent evidence, which indicates that falling progesterone levels, rather than a steady high or low concentration of the steroid, can lead to significant changes in the inherent excitability of GABA‐containing circuits.…”

“…Both experimentally induced and naturally occurring decreases in systemic progesterone levels in rats are associated with an increase in anxiety or aggression levels (Mora et al 1996; Smith et al 1998 a ; Gulinello et al 2003 a , b ; Olsson et al 2003). At the cellular level, differences in the pharmacological properties of GABA modulatory agents emerge after withdrawal from progesterone.…”

Control of Breathing During Exercise

“…For example, Brack et al (52) found that injection of a panicogenic agonist into the PAG of anesthetized rats elicited a hyperpnea, and a hyperpnea is a common feature of a panic attack (12,256,257).…”

Severe respiratory changes at end stage in a FUS-induced disease state in adult rats

“…Lower weights allow for less viral vector to be administered on a per kg basis, and more stable body weights helped ensure consistency of motor and lung function analyses. Estrus cycle was not controlled for in this study although some reports have shown increased respiratory frequency in the diestrus phase [55]. For vector administration, viral vectors were diluted to 200 μl in lactated Ringer’s solution and drawn up in a 1 ml syringe attached to a 30 gauge needle.…”