%0 Journal Article
%T A dynamic model of circadian rhythms in rodent tail skin temperature for comparison of drug effects
%A Dorothee Girbig
%A Karsten Keller
%A Katja Prelle
%A Vladimir Patchev
%A Richardus Vonk
%A Bernd-Wolfgang Igl
%J Journal of Circadian Rhythms
%D 2012
%I BioMed Central
%R 10.1186/1740-3391-10-1
%X The rapid drop in hormone production during the climacteric implies a variety of changes in the physiology of the female body. This can lead to hot flushes which occur in around 70% of all women in Europe and North America [1]. Hot flushes are characterized by a sudden sensation of intense heat, accompanied by flushing of certain peripheral skin parts as well as intensive sweating. The pathophysiology of hot flushes is not yet completely understood, but their occurrence is assumed to originate in disturbances of the thermoregulatory processes in the hypothalamus, which acts as the body's thermostat [2].An animal model suitable for assessing the effectiveness of drug candidates in hot flush treatment is the ovariectomized rat model [3]. Here, a menopause-like state is simulated by ovary removal (ovariectomy, OVX), resulting in estrogen deprivation. It is assumed that the lack of estrogens lowers the set point for the activation of heat-dissipating mechanisms. As shown in Figure 1, this results in a lack of decrease in tail skin temperature during the rats' active phase at night and, consequently, flattening of the circadian oscillations in this parameter. Then, the effectiveness of a substance in compensating the effects of estrogen deprivation can be assessed by its capability to restore the amplitude of circadian rhythms in the tail skin temperature.The ovariectomized rat model has been widely applied for the evaluation of substance effects for treating menopausal syndromes [4-8] and for investigating the underlying pathophysiology [9].So far, there have been limited efforts in developing sophisticated techniques based on characteristic properties of the rhythms when evaluating the effects of a tested substance on circadian rhythms. Important characteristics are (1) a dynamic amplitude function monitoring the adaptation of oscillations to new treatments and (2) the capability of the circadian pacemaker to maintain limit cycles after sufficient adaptation to the tre
%U http://www.jcircadianrhythms.com/content/10/1/1