Diurnal rhythms of thyroid function in chicks

Newcomer, W. S.

doi:10.1016/0016-6480(74)90142-7

Cited by 79 publications

(14 citation statements)

References 13 publications

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“…This study confirms the reciprocal relationship between the daily rhythms in the concentration of plasma T4 and T3 in the chicken (Newcomer, 1974;Klandorf et al 1978Klandorf et al , 1981Kühn, Decuypere, Colen & Michels, 1982;Sharp & Klandorf, 1984). These rhythms are, in part, a direct consequence of the lighting pattern since their amplitudes decrease or dis¬ appear in birds exposed to constant darkness or light for 24 h or more.…”

Section: Discussionsupporting

confidence: 86%

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Sharp¹,

Klandorf²,

Lea³

1984

Journal of Endocrinology

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The effects of pinealectomy on the daily rhythms of concentrations of tri-iodothyronine (T3) and thyroxine (T4) were investigated in sexually immature female chickens exposed to 21-, 24- and 27-h cycles of light and darkness, or to extended periods of light or darkness for more than 24 h. In pinealectomized and control birds, rhythms in levels of plasma T3 and T4 were entrained by all lighting cycles and decreased in amplitude or disappeared in continuous light or darkness. In pinealectomized and control birds held on 21-h (11 h light:10 h darkness; 11L:10D) and 24-h (14L:10D) lighting cycles, the peak of the T4 rhythm coincided with, or lagged, the trough in the rhythm of T3 while in birds held on a 27-h (14L:13D) lighting cycle, the peak of the T4 rhythm preceded the trough in the rhythm of T3. Pinealectomy resulted in significant effects on the phases or amplitudes of rhythms of T3 or T4 in all lighting schedules except 4L:20D. However, these effects were not consistent in direction between experimental groups and were, therefore, of doubtful physiological significance. Pinealectomy increased the mean level of plasma T4 in birds exposed to continuous light or darkness or to 4L:20D. A corresponding reduction in mean levels of plasma T3 was seen in birds exposed to continuous light or darkness. It is concluded that under the lighting conditions investigated pinealectomy had no clear effect on the phases or amplitude of daily rhythms of levels of T4 or T3. However, after the effects of the feeding pattern on thyroid hormone rhythms imposed by the lighting cycle were removed by placing birds in constant lighting conditions, pinealectomy appeared to exert an inhibitory action on thyroid function.

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Section: Discussionsupporting

confidence: 86%

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Sharp¹,

Klandorf²,

Lea³

1984

Journal of Endocrinology

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“…The physiological significance of this phenomenon is uncertain (Astier and Newcomer 1978). In the present study the T 3 / T 4 -ratio was 0.07 at 0-time which is in the same range of magnitude (0.06 to 0.14) as that reported for chicks (Newcomer 1974). …”

Section: Discussionsupporting

confidence: 81%

Propranolol Induced Changes in Plasma Catecholamine, Corticosterone, T₄, T₃and Prolactin Levels in the Pigeon

Hissa¹,

Jc²,

Tm³

et al. 1982

Horm Metab Res

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Concentrations of plasma noradrenaline, adrenaline, corticosterone, thyroxine (T4), triiodothyronine (T3) and prolactin were measured in pigeons at 22 degrees C after intravenous injection of propranolol (1 mg/kg). An increase in catecholamines occurred in 5 or 15 min. T4, T3 and prolactin increased within 30 and 60 min after injection, however, after correction for the differences in plasma protein content, only the concentration of prolactin was significantly above the control values. It is concluded that the impairment of heat production produced by propranolol in birds is not primarily induced by inhibition of the secretion or release of these hormones.

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“…It is also possible that the elevated plasma levels reflect either decreased peripheral use of the thyroid hormones or a phase shift in the diurnal rhythm of thyroid activity. Several investigators have reported a diurnal variation in plasma levels of thyroid hormones in the chicken (Sadovsky and Bensadoun, 1971;Newcomer, 1974;May, 1978). It has been shown that the diurnal pattern of T 4 secretion differs from that of T 3 , a finding that suggests more complex thyroid regulatory mechanisms than previously thought.…”

Section: Resultsmentioning

confidence: 93%

Effects of Light Environment and Pinealectomy on Growth and Thyroid Function in the Broiler Cockerel

1980

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Four replicate experiments were conducted to determine the effects of pinealectomy and environmental lighting on growth and thyroid function in broiler cockerels. Birds were housed in battery brooders under a 14L:10D white light regime for 2 weeks and then allotted to lightcontrolled chambers. The light environments were 14L:10D white, 14L:10D green (narrow band, 545 nm peak), and constant dark. Surgery was performed when the chicks were 3 to 5 days old. At the end of the 32-day experimental period, weight gain and thyroid weights were measured and plasma triiodothyronine (T 3 ) and thyroxine (T 4 ) levels were determined by radioimmunoassay.Pinealectomy significantly (P<.05) depressed growth but did not affect thyroid weight or circulating plasma levels of T 3 or T 4 .Birds grown under white light were significantly (P<,05) lighter in weight than those grown under green light or darkness. Plasma T 4 levels were significantly (P<.05) elevated in chicks grown under green light while T 3 levels were signficantly (P<.05) higher in dark-treated birds when compared to either light treatment.

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Diurnal rhythms of thyroid function in chicks

Cited by 79 publications

References 13 publications

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Propranolol Induced Changes in Plasma Catecholamine, Corticosterone, T₄, T₃and Prolactin Levels in the Pigeon

Effects of Light Environment and Pinealectomy on Growth and Thyroid Function in the Broiler Cockerel

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Diurnal rhythms of thyroid function in chicks

Cited by 79 publications

References 13 publications

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Influence of lighting cycles on daily rhythms in concentrations of plasma tri-iodothyronine and thyroxine in intact and pinealectomized immature broiler hens (Gallus domesticus)

Propranolol Induced Changes in Plasma Catecholamine, Corticosterone, T4, T3and Prolactin Levels in the Pigeon

Effects of Light Environment and Pinealectomy on Growth and Thyroid Function in the Broiler Cockerel

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Propranolol Induced Changes in Plasma Catecholamine, Corticosterone, T₄, T₃and Prolactin Levels in the Pigeon