Circadian Rhythm in Pineal <i>N</i>‐Acetyltransferase Activity: Phase Shifting by Dark Pulses (III)

Binkley, Sue; Mosher, Karen; White, Benjamin H.

doi:10.1111/j.1471-4159.1985.tb04075.x

Cited by 11 publications

(14 citation statements)

References 19 publications

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“…In the chick pineal gland, melatonin is produced from serotonin through the action of the enzyme serotonin N-acetyltransferase (NAT) [ Binkley, 1981;Takahashi and Menaker, 19841. The chick pineal gland behaves as a circadian pacemaker [Binkley and Geller, 1975a;Binkley et al, 1981;Deguchi, 1979a;Kasal et al, 19791 and has a photoreceptive capacity [Deguchi, 19811. Explante pineal glands remain photosensitive in culture and NAT activity can be er trained by light cycles [Wainwright and Wainwright, 19801. A diurnal cycle c light and dark entrains large-amplitude rhythms of NAT activity in glands main tained in culture (Binkley et al, 1978;Deguchi, 1979~1.…”

Section: Introductionmentioning

confidence: 99%

Ontogeny of Light‐Induced Decrease of N‐Acetyltransferase Activity in Explanted Chick Pineal Glands

Rudeen

Creighton

Bylund

et al. 1990

Journal of Pineal Research

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The ontogeny of chick pineal serotonin N-acetyltransferase (NAT) activity was investigated in explanted chick pineal glands at 4, 10 and 21 d of age. Nocturnal levels of the enzyme and the response of the enzyme to light exposure were determined in pineal glands maintained in short-term culture at each age. The results indicate that nocturnal NAT activity was increased in the glands from older birds. Nocturnal levels of NAT activity at the time of the initiation of the experiment were threefold greater in glands from 21-d-old birds as compared to that in glands from 4-day-old chicks. The response to light was similar in all three ages examined; light induced a significant decrease in NAT activity within 60 min in explanted glands from 4-d-old chicks and within 180 min in the glands from the 10- and 21-d-old chicks. A paradoxical transient increase in enzyme activity occurred immediately (within 5 min) following light exposure which was significant in the glands from the youngest chicks, and present, but more variable, in the older chicks. These data indicate that the nocturnal enzyme activity is greater in glands from older birds, but that light exposure of explanted glands initiates a transient rise followed by a decrease in NAT activity at all three ages.

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Section: Introductionmentioning

confidence: 99%

Ontogeny of Light‐Induced Decrease of N‐Acetyltransferase Activity in Explanted Chick Pineal Glands

Rudeen

Creighton

Bylund

et al. 1990

Journal of Pineal Research

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“…They ascribe the responses to a hypothetical "morning oscillator." We [Binkley et al, , 1983 measured larger phase shifts (6 hr advances and -2 hr delays) for chick pineal NAT following light or dark pulses (4 hr). We suggested that the change from delays to advances in the phase response curves for NAT is caused by the change to refractoriness (Binkley, 1983a,b].…”

Section: Discussionmentioning

confidence: 99%

“…However, the phase of the NAT profile is consistent within 2 hr. NAT rises after lights out and returns to low levels by Binkley [1983] done with rats 26 days old at 2,430 lux. Otherwise, the light intensity was 1,080 lux.…”

Section: Nat Profiles Varied In Ld 14: 10mentioning

confidence: 92%

Phase Shift of Daily Profiles of N‐Acetyltransferase in the Rat Pineal Gland

White

Mosher

Binkley

1985

Journal of Pineal Research

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Pineal N-acetyltransferase activity (NAT) has a circadian rhythm with peak values in the dark time and low values in the light time. NAT time profiles were measured in rats exposed to LD 14:10, to constant dark, and to acute (less than 48 hr) light-dark treatments. In all experiments, imposition of light suppressed NAT. The phase of the dark time NAT cycle was altered 2 hr or less by the following treatments: 3 hr light in the early subjective night, 3 hr light in the late subjective night, 2 hr or 6 hr light in the early subjective day, 4 hr early lights-on, 1 day of constant dark, or 1 day of constant light. When light was extended 4 hr into the dark time, NAT rose at lights out but fell again as the time of "expected" dawn approached. In contrast, the phase of the NAT cycle was shifted 12 hr (180 degrees) within 72 hr by reversing the phase of the light-dark cycle. NAT did not rise in the first dark period (coincident with the time of the subjective light time). The amplitude of the first shifted cycle was less than four control NAT profiles measured in rats kept in the original (unshifted) light-dark cycle.

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“…First, removing the sources of rhythmic NAT activity in birds-the eyes, the pineal gland, or bothabolishes rhythms in locomotor activity (Gaston and Menaker, 1968;Nyce and Binkley, 1977;Ebihara et al, 1984;Underwood and Siopes, 1984). Second, continuous melatonin administration abolishes rhythmicity (Turek et al, 1976;Binkley and Mosher, 1985). Third, chick pineal glands are capable of rhythmic NAT activity, light responses, and rhythmic mel-atonin secretion when the pineal glands are isolated in organ cultures (Binkley et al, 1978;Deguchi, 19796;Kasal et al, 1979;Wainwright and Wainwright, 1979;Takahashi et al, 1980).…”

Section: Interpretation Of Reentrainment Of the Nat Activity Rhythmmentioning

confidence: 99%

“…We previously reported on the manner in which the NAT activity rhythm in chick pineal glands is affected by light and dark in vivo. Our list of phenomena we can now correlate and for which we can offer explanations includes entrainment by 24-h light-dark cycles, persistence in DD, damping by LL, measurement of photoperiod, light break and resonance experiments, resetting by light and dark pulses, frequency demultiplication, and range of entrainment (Binkley et al, 1973(Binkley et al, , 1981(Binkley et al, , 1985Binkley, 1976Binkley, , 1983a.…”

Section: Enzyme Model For Pineal Clock Functionmentioning

confidence: 99%

Circadian Rhythm in Pineal N‐Acetyltransferase Activity: Rapid Phase Reversal and Response to Shorter than 24‐Hour Cycles (IV)

Binkley

Mosher

White

1987

Journal of Neurochemistry

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N-Acetyltransferase (NAT) is an enzyme whose rhythmic activity in the pineal gland and retina is responsible for circadian rhythms in melatonin. The NAT activity rhythm has circadian properties such as persistence in constant conditions and precise control by light and dark. Experiments are reported in which chicks (Gallus domesticus), raised for 3 weeks in 12 h of light alternating with 12 h of dark (LD12:12), were exposed to 1-3 days of light-dark treatments during which NAT activity was measured in their pineal glands. (a) In LD12:12, NAT activity rose from less than 4.5 nmol/pineal gland/h during the light-time to 25-50 nmol/pineal gland/h in the dark-time. Constant light (LL) attenuated the amplitude of the NAT activity rhythm to 26-45% of the NAT activity cycle in LD12:12 during the first 24 h. (b) The timing of the increase in NAT activity was reset by the first full LD12:12 cycle following a 12-h phase shift of the LD12:12 cycle (a procedure that reversed the times of light and dark by imposition of either 24 h of light or dark). This result satisfies one of the criteria for NAT to be considered part of a circadian driving oscillator. (c) In less than 24-h cycles [2 h of light in alternation with 2 h of dark (LD2:2), 4 h of light in alternation with 4 h of dark (LD4:4), and 6 h of light in alternation with 6 h of dark (LD6:6)], NAT activity rose in the dark during the chicks' previously scheduled dark-time but not the previously scheduled light-time of LD12:12. In a cycle where 8 h of light alternated with 8 h of dark (LD8:8), NAT activity rose in both 8-h dark periods, even though the second one fell in the light-time of the prior LD12:12 schedule.(ABSTRACT TRUNCATED AT 250 WORDS)

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Circadian Rhythm in Pineal N‐Acetyltransferase Activity: Phase Shifting by Dark Pulses (III)

Cited by 11 publications

References 19 publications

Ontogeny of Light‐Induced Decrease of N‐Acetyltransferase Activity in Explanted Chick Pineal Glands

Ontogeny of Light‐Induced Decrease of N‐Acetyltransferase Activity in Explanted Chick Pineal Glands

Phase Shift of Daily Profiles of N‐Acetyltransferase in the Rat Pineal Gland

Circadian Rhythm in Pineal N‐Acetyltransferase Activity: Rapid Phase Reversal and Response to Shorter than 24‐Hour Cycles (IV)

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