Ultradian rhythms

Naber D., Wirz-Justice A., Kafka M. S., Wehr T. A. (1980). Dopamine receptor binding in rat striatum ultradian rhythm and its modification by chronic imipramine. Psychopharmacology (Berl). 68(1), 1-5. 

C. Wagner, S. R. Caplan, and G. S. Tannenbaum, Genesis of the ultradian rhythm of GH secretion A new model unifying experimental observations in rats. Am. J. Physiol. 275, E1046-1054 (1998). 

The ultradian sleep—wake and temperature rhythm produced by 3rd ventricle infusion of TGFa closely resembles the effect of a focal excitotoxic lesion of SPZ neurons (Lu et al 2001). This ultradian rhythm is normally suppressed by circadian control and is disinhibited when SPZ neurons fail to relay SCN circadian information to sleep—wake circuits. Our results indicate that chronic TGFa administration uncouples SPZ neurons from sleep-regulatory circuits and that SPZ neurons expressing the EGFR transmit circadian information from the SCN to sleep—wake centres, in addition to likely regulating circadian locomotor activity. 

Lavie P, Zomer J. Ultrashort sleep-waking schedule. II. Relationship between ultradian rhythms in sleepability and the REM-NONREM cycles and effects of the circadian phase. Electroencephalogr and Clin Neurophysiol 1984 57 35 -2. 

Le Fur, I. et al., Analysis of circadian and ultradian rhythms of skin surface properties of face and forearm of healthy women, J. Invest. Dermatol., 117, 718, 2001. 

For linear systems, the principle of superposition applies, and different oscillatory modes can evolve independently of one another. However, biological systems in general are not linear, and separation of different regulatory mechanisms may not be justified, even when they involve different time scales. One type of phenomenon that can arise from the interaction between two oscillatory modes is modulation of the amplitude and frequency of the faster mode in dependence of the phase of the slower mode. This type of phenomenon was demonstrated in Fig. 12.2c where the frequency of the myogenic mode fjast changes in step with the amplitude of the TGF-mediated mode. Similar modulation phenomena can be expected to occur in many other biological systems such as, for instance, the interaction between the circadian and the ultradian rhythms of hormone secretion [25]. 

Tannenbaum GS, Ling N (1984) The interrelationship of growth hormone (GH)-releasing factor and somatostatin in generation of the ultradian rhythm of GH secretion. Endocrinology 775 1952-1957. 

Various rhythms and cycles in the physiological and pathological contexts can be examined. Specifically, circadian rhythms last about 24 h. Rhythms that are longer than 24 h are called infradian rhythms, such as the menstrual cycle [31, 32], Cycles that are shorter than 24 h are called ultradian rhythms, such as the firing rate of neurons and the rhythm of heartbeats. Currently in biomedicine, the circadian rhythm is the one that has been studied the most extensively [32], More studies on other patterns are still needed. In addition to biological and environmental rhythms, social rhythms and cycles such as school years, as well as the frequencies of biological, environmental, and social events should also be considered. 

Tannenbaum, G.S. and J.B. Martin (1976) Evidence for an endogenous ultradian rhythm governing growth hormone secretion in the rat. Endocrinology 98, 562-570. 

J. J. Morrissey, D.P. Lapenson, and D.J. Waxman (1989). Signalling elements in the ultradian rhythm of circulating growth hormone regulating expression of sex-dependent forms of hepatic cytochrome P450. Endocrinology 125, 2935-2944. 

Beyond the two-hour ultradian rhythms, our lives are also set to the circadian or diurnal rhythm of the daily cycle that regulates sleep and wakefulness. In fact, our biological clock is set not to a twenty-four-hour day but to one that lasts closer to twenty-five hours. Presumably that gap be-... 

Dowse, H.B., J.C. Hall J.M. Ringo. 1987. Circadian and ultradian rhythms in period mutants of Drosophila melanogaster. Behav. Genet. 17 19-35. 

Dowse, H.B. J.M. Ringo. 1993. Is the circadian clock a meta-oscillator Evidence from studies of ultradian rhythms in Drosophila. In Molecular Genetics of Biological Rhythms, M.W. Young, ed. Marcel Dekker, New York, pp. 195-220. 

Lloyd, D. M. Stupfel. 1991. The occurrence and functions of ultradian rhythms. Biol. Rev. 66 275-99. 

Ultradian rhythms in Drosophila, 471 in GH secretion, 337 in hormones, 303 in insulin and glucose, 340 Universal constant, see Period-doubling bifurcations... 

Ultradian rhythms have periods shorter than 20 hr. Examples of these rhythms are the electrocardiogram, respiration, peristalsis in the intestine, etc. 

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