Circadian changes

Friedman, A. H. 8r Walker, C. A. (1969). Rat brain amines, blood histamine and glucose levels in relationship to circadian changes in sleep induced by pentobarbitone sodium. J. Physiol. 202, 133-46. 

O Neill R. D., Fillenz M. (1985). Simultaneous monitoring of dopamine release in rat frontal cortex, nucleus accumbens and striatum effect of drugs, circadian changes and correlations with motor activity. Neuroscience 16(1), 49-55. 

Paulson P. E., Robinson T. E. (1994). Relationship between circadian changes in spontaneous motor activity and dorsal versus ventral striatal dopamine neurotransmission assessed with on-line microdialysis. Behav. Neurosci 108(3),... 

Both clinical and experimental studies have shown that a number of transmitter receptors and amine transport processes show circadian changes. It is well established that depression is associated with a disruption of the circadian rhythm as shown by changes in a number of behavioural, autonomic and neuroendocrine aspects. One of the main consequences of effective treatment is a return of the circadian rhythm to normality. For example, it has been shown that the 5-HT uptake into the platelets of depressed patients is largely unchanged between 0600 and 1200 hours, whereas the 5-HT transport in control subjects shows a significant decrease over this period. The normal rhythm in 5-HT transport is only reestablished when the depressed patient responds to treatment. Thus it may be hypothesized that the mode of action of antidepressants is to normalize disrupted circadian rhythms. Only when the circadian rhythm has returned to normal can full clinical recovery be established. 

Several diseases with established oscillatory rhythm in their pathogenesis have been identified. In the case of asthma, chronotherapy has been extensively studied [9, 10]. Airway resistance increases progressively at night in asthmatic patients [11], Circadian changes are seen in normal lung function, which reaches a low point in the early morning hours. This dip is particularly pronounced in people with asthma. 

Brady J. (1975) Circadian changes in central excitability - the origins of behavioural rhythms in tsetse flies and other animals J. Ent. (A) 50, 79-95. 

Metzger, G., Massari, C., Etienne, M.C., Comisso, M., Brienza, S., Touitou, Y., Milano, G., Bastian, G., Misset, J.L., Levi, F. Spontaneous or imposed circadian changes in plasma concentrations of 5-fluorouracil coadministered with folinic acid and oxaliplatin relationship with mucosal toxicity in patients with cancer. Clin. Pharmacol. Ther. 1994, 56 190-201. 

Mai LM, Pan J-T (1995) Bombesin acts in the suprachiasmatic nucleus to affect circadian changes in tuberoinfundibular dopaminergic neuron activity and prolactin secretion. Endocrinology 755 4136-4167. 

Shieh K-R, Pan J-T (1995) An endogenous cholinergic rhythm may be involved in the circadian changes of tuberoinfundibular dopaminergic neuron activity in ovariectomized rats treated with or without estrogen. Endocrinology 736 2383—2388. 

Shieh K-R, Chu Y-S, Pan J-T (1997) Circadian change of dopaminergic neuron activity effects of constant light and melatonin. Neuroreport 5 2283-2287. 

Lemmer, B. Nold, G. Circadian changes in estimated hepatic blood flow in healthy subjects. Br. J. Clin. Pharmacol. 1991, 52 (5), 627-629. 

Kemp GJ, Blumsohn A, Morris BW. Circadian changes in plasma phosphate concentration, urinary phosphate excretion and cellular phosphate shifts. 

Characterizing a drug s circadian pharmacokinetics and pharmacodynamics can enable investigators to temporally target the administration time and intensity to maximize patient response and minimize patient toxicity. In these models, the rhythmic displacement in the effect curve is caused by the underlying PK circadian changes in clearance, not any PD interaction. Flence, a direct PD model can stiU be used to model the PD interaction. 

The changes in GST observed post-halothane anesthesia are small and it is possible that they may reflect circadian changes in the enzyme levels. To study this we measured plasma B, concentrations in 30 healthy volunteers after an overnight fast and subsequently at 3, 6, and 24 hr, i.e., the sampling intervals used for the study on the effects of halothane on GST. We could detect no signiflcant increase in B, subunits over this time period. 

For example, the unicellular marine alga Gonyaulax undergoes dramatic circadian changes in the intensity of its bioluminescence. Over one 10-day period the luminescence peaked every 22.99 0.01 hours. ... 

Fig. 11.5. (a) Circadian rhythm in per mRNA abundance in Drosophila (Hardin et al, 1990). (b) The periodic variation of total PER protein is shown to lag by several h after the circadian change in per mRNA. The curves show the variation of per mRNA and PER in the eyes and brain of Drosophila flies (Zeng et al, 1994). 

In the same review article, Goad [36] described without explanation the role of insulin and glucagon in the regulation of circadian changes in HMGR activity during cholesterol biosynthesis. 

Depends upon circadian changes in rats and humans... 

Fig. 8. Circadian changes of the A6 desaturation of linoleic to y-linolenic acid in mouse liver.

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