various body clocks with one another and with the local time zone. Classic work demonstrates that the SCN is necessary for maintaining circadian rhythms in numerous processes, including sleep, feeding, drinking, melatonin production, and reproductive
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Jonathan D Johnston and Debra J Skene
, as pinealectomy abolishes detectable melatonin in the blood ( Lewy et al . 1980 a ). Circadian rhythmicity of pineal melatonin synthesis Concentrations of melatonin in the blood exhibit a pronounced circadian rhythm, with elevated levels during the
Qinghua Wang, Jing Tang, Shujun Jiang, Zan Huang, Anying Song, Siyuan Hou, Xiang Gao, and Hai-Bin Ruan
), ITA and XIAP ( Jordan et al. 2001 ), UNC5H1 ( Williams et al. 2003 ), ROR2 ( Matsuda et al. 2003 ) and RORα ( Wang et al. 2010 ) to regulate neural development, cell apoptosis and proliferation and circadian rhythm. We and others have showed
Miho Sato, Keiko Nakahara, Mikiya Miyazato, Kenji Kangawa, and Noboru Murakami
expression is regulated by circadian rhythm, starvation, CCK, gastrin, and other factors, possibly via extracellular fluid or satellite cells. CCK and gastrin receptors are expressed in vagal afferent neurons, implying that the regulation of GHS-R gene
Christophe Breton
. In addition, fasted adult offspring from FR70 dams during gestation displayed no marked reduced α-MSH-immunoreactive fibre projection intensity in the PVN ( Breton et al . 2009 ). Maternal reduced nutrition modifies circadian rhythms in the offspring
W. A. CHAMLEY, L. R. FELL, F. P. ALFORD, and J. R. GODING
It has been suggested that prolactin secretion exhibits a circadian rhythm and is related to ovine growth hormone (OGH) secretion in the ewe (Davis, 1972; Davis & Borger, 1972, 1973). Prolactin levels in ovine jugular vein blood can fluctuate rapidly, which makes it difficult to establish a temporal pattern of secretion. This problem may be overcome by continuous blood sampling, used here to measure prolactin in rams over 24 h. This secretory pattern is compared with the secretory pattern of OGH in the same animals. In particular, the interrelationship between prolactin and OGH is examined as well as attempting to define a circadian rhythm for the secretion of these hormones.
Five Merino rams were used. Skin folding for the neck and trunk regions of each animal was scored by three independent observers (Carter, 1943). This confirmed that two rams (nos. 174 and 179) had minimal skin folding (mean score 2/18)
P. H. ROWE, G. A. LINCOLN, P. A. RACEY, J. LEHANE, M. J. STEPHENSON, J. C. SHENTON, and T. D. GLOVER
SUMMARY
Testosterone was measured in the peripheral blood plasma of normal men by radioimmunoassay. The results were analysed to test for the possible existence of a circadian rhythm, for fluctuations superimposed on any such rhythm, and for day-to-day variations. Unequivocal evidence of a circadian rhythm was found in all but one of the subjects studied and the cycle appeared to be accompanied by a series of fluctuations of lower amplitude lasting for 1–2 h. Samples taken from the same subjects on consecutive days showed marked variation between days, but no regular cyclic pattern. The possible existence of such a cycle is not, however, eliminated. On the basis of all the data obtained a regime is suggested for the collection of blood samples from individuals whose androgenic status is to be assessed.
LEAH YOGEV and JOSEPH TERKEL
Androgen-sterilized female rats were obtained by administering 10 μg testosterone propionate to pups on day 2 after birth. In contrast with ovariectomized adults, androgenized adult female rats are incapable of responding to cervical stimulation by secreting prolactin in the nocturnal surge pattern. In spite of the loss of this pattern the androgenized female rats still exhibited a daily circadian rhythm of prolactin secretion with afternoon levels three times higher than those after midnight.
C. L. RALPH, R. W. PELHAM, S. E. MACBRIDE, and DIANE P. REILLY
SUMMARY
The melatonin (N-acetyl-5-methoxytryptamine) content of the pineal body and serum of White Leghorn cockerels (Gallus domesticus) appears to vary cyclically, with a higher level of both found at the mid-point of the dark period than at the mid-point of the light period when the animals were kept in a diurnal light cycle. These rhythmic variations persisted, although with an apparently lower amplitude, when the animals were maintained in continuous darkness for 2 weeks. The oscillations appeared to be free-running, circadian rhythms and to be phase-locked with the locomotor activity rhythms of the individual birds studied.
H. SIMPSON
SUMMARY
The circadian rhythm of urinary 17-hydroxycorticosteroid (17-OHCS) excretion in Europeans and Equatorial Amerindians has been compared. The precise daily habits of the Equatorial Amerindians did not result in a more marked rhythm of 17-OHCS excretion. Amerindian men and women excreted much less 17-OHCS than their European counterparts; the difference is still substantial when body weight is taken into consideration. The rhythm of 17-OHCS excretion in Amerindians had a minimum and maximum corresponding to their early reveille and bedtime confirming the importance of environmental stimuli in setting the timing of the rhythm.
