Estrous correlated modulations of circadian and ultradian wheel-running activity rhythms in LEW/Ztm rats

Abstract

WOLLNIK, F. AND F. W. TUREK. Estrous correlated modulations of circadian and ultradian wheel-running activity rhythms in LEW!Ztm rats. PHYSIOL BEHAV 43(3) [389][390][391][392][393][394][395][396] 1988.-Estrogen treatment alters the expression ofultradian activity rhythms in male and female LEW/Ztro rats. This finding raises the possibility tbat the expression of ultradian rhythms may vary on different days of the estrous cycle. To test this hypothesis, we recorded the circadian and ultradian wheel-running activity rhythms of entrained (LD 12: 12) and free-running sexually mature LEW/Ztm females during their 4-or 5-day estrous cycle. The mean daily activity, the duration of activity, the circadian period of activity, and the occurrence of ultradian rhythms differed significantly among the days of the estrous cycle. ln LD 12: 12, the phase angle difference between the beginning of activity and light offset varied reliably in 5-day cycling animals. The highest daily mean of activity, the longest duration, and the shortest circadian period length were observed on the day of estrus in both entrained and free-running animals. The day of estrus was characterized by a constant high level of activity throughout the activity phase, while the days following ovulation showed a bi-or trimodal activity pattern. Power spectrum analysis revealed significant ultradian components for the days of metestrus and diestrus, but only circadian components for the days of proestrus and estrus. These results were interpreted as indicating that endogenous changes in circulating hormone levels can induce changes in the ultradian and circadian patterns of wheel-running activity in LEW/Ztm rats. Wheel-running activityEstrous cycle Ultradian and circadian rhythms Laboratory rat STEROID hormones have been reported to modulate the amplitude, phase, and period of mammalian circadian rhythms (for review see [25,30]). In female hamsters and rats, the time of activity onset fluctuates with the estrous cycle in animals entrained to a light-dark cycle as well as in animals maintained under constant illumination or darkness [2,7,14,22]. Activity onset in hamsters occurs earlier on both proestrus and estrus, the days of the estrous cycle when serum levels of estrogen are high [5], whereas in rats the activity onset is earlier only on the day of estrus [2]. Exogenously supplied gonadal hormones also alter the periodicity of circadian rhythms. Silastic estrogen-filled capsules that produce proestrous levels of estrogen shorten the period of the free-running rhythms in ovariectomized rats and hamsters [1,14,31], and increase the total amount of wheelrunning activity [11,22]. Although progesterone alone does not affect circadian rhythms [14,17,22], it can antagonize estrogen's action on activity rhythms in rats and hamsters [3,4,17,22]. It is likely that the interaction of progesterone and estrogen modulates the circadian rhythm of activity in female rats and hamsters on a day-to-day basis [2,22]. Recent studies indicate that gonadal hormones can also alte...

Seasonal change in the temporal organization of wheel-running activity of the European Hamster,Cricetus cricetus

“…1; HAMIIIII). This 4-day pattern probably reflects estrous correlated modulations similar to those described for golden hamsters [5) and rats [6,7). curs spontaneously under long photoperiods [8,9].…”

Oestrus cycle of the Desert hamster (Phodopus roborovskii, Satunin, 1903)

“…23,24 The Desert hamster differs from these species in that oestrus-correlated changes in wheel-running activity are only subtle. A detailed analysis revealed no significant effects on activity onset, but a significant lengthening of activity duration during early oestrus and oestrus.…”

“…For example, activity levels increase on the days of pre-oestrus and oestrus in Golden hamsters [20][21][22] and rats. 23 In addition, activity onset occurs earlier in the oestrus cycle in rats 23,24 and Golden hamsters 25 resulting in a so-called 'scalloping' of activity onset. Oestrus-correlated changes in locomotor activity rhythms have been interpreted as a strategy for increasing the probability for physical contact between males and females and thus increasing mating success.…”

Adrenal peripheral clock disruption leads to altered circadian behavioral responses to voluntary exercise in middle-aged female mice

“…To be noted, however, is that any physiological or pathological circumstances or factors resulting in altered manifestations of BT and/or physical activity will reduce the reliability of these biomarkers for estrous cycle. Wollnik and Turek (1988) once observed in young LEW/Ztm female rats that the day of estrus was characterized by a constant high level of activity throughout the active phase, whereas on the days of metestrus and diestrus the total amount of activity decreased and bi-or tri-modal activity patterns were apparent. The estrous correlated variation in the activity pattern can be best explained by the serum levels of estrogen during the cycle (Morgan & Pfaff 2001).…”

“…Moreover, the amount of voluntary running in female rodents is known to vary across the estrous cycle, peaking during proestrus (Wollnik & Turek 1988;Ogawa et al 2003). Although evidence supports the use of core BT as a biomarker for studying circadian rhythm (Reilly & Brooks 1990), possible uses of activity rhythms as markers of estrous cycle have not yet been intensively studied.…”