Persistent Rhythms of Pineal and Serum Melatonin in Cockerels in Continuous Darkness

Ralph, Charles L.; Pelham, Russell W.; Macbride, Steven E.; Reilly, Diane P.

doi:10.1677/joe.0.0630319

Cited by 43 publications

(15 citation statements)

References 8 publications

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“…These experiments and others strongly suggest that the pineal of the sparrow has a pacemaking function and that it is hormonally coupled to the rest of the circadian system. In chickens, there is a circadian rhythm of melatonin in the pineal and the serum (7,8) and this serum rhythm is undetectable after pinealectomy (9). The results reported here unequivocally show that a rhythmic hormonal signal (melatonin) is released from the chicken pineal.…”

Section: Discussionsupporting

confidence: 59%

See 1 more Smart Citation

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Takahashi

Hamm

Menaker

1980

Proc. Natl. Acad. Sci. U.S.A.

222

104

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The pineal gland of birds contains one or more circadian oscillators that play a major role in overall temporal organization. We have developed a flow-through culture system for the isolated pineal by which we can measure the release of melatonin continuously from suerrfused glands over long pr riods of time. Chicken pineals release melatonin rhythmically, and these rhythms persist in vitro with a circadian oscillation. In light cycles the release of melatonin is strongly rhythmic; however, in constant conditions the amplitude of the rhythm is lower and appears to be damping. Light has at least two effects upon the isolated pineal: cyclic light input synchronizes the rhythm, and acute light exposure at ni ht rapidly inhibits melatonin release. The Behavioral and biochemical experiments strongly suggest that the avian pineal gland contains, or is, a circadian oscillator that plays a major role in the overall temporal organization of the animal (for review, see ref. 1). Removal of the pineal eliminates the free-running circadian rhythms of locomotor activity and body temperature in the house sparrow (2, 3). Transplantation of pineal tissue into the anterior chamber of the eye rapidly restores rhythmicity in arrhythmic pinealectomized sparrows and transfers the phase of the donor's rhythm to the host (4-6). These results argue that the pineal gland functions as a pacemaker within the circadian system of the house sparrow.Apart from the pineal's role in controlling behavioral rhythms, the biochemistry of the avian pineal itself is dramatically rhythmic. The melatonin content of chicken pineals oscillates in a circadian fashion (7,8) and contributes to a rhythm of melatonin in the serum (9). The synthesis of melatonin in the chicken pineal appears to be regulated by the activity of the enzyme serotonin N-acetyltransferase (7), which oscillates with a circadian period in vivo (10). The regulation of the rhythm of pineal N-acetyltransferase-which in rats is under the control of norepinephrine from the sympathetic fibers that innervate the pineal (11-13)-appears to be different in birds (14). Although it is not clear how the oscillation in N-acetyltransferase activity in the avian pineal is generated, it is consistent with the data to conclude that the controlling mechanism is within rather than external to the pineal.Recent experiments have established several important properties that are expressed by the isolated pineal gland in organ culture. Four laboratories have documented an increase and decrease in N-acetyltransferase activity in isolated pineals for at least 24 hr in organ culture (15)(16)(17)(18)(19).Kasal et al. (17) have shown that the rhythm persists for two cycles in constant darkness with a circadian period in vitro. However, the difficulty in measuring rhythms in populations MATERIALS AND METHODS Chemicals. Carrier-free, high-specific-activity 125I was purchased from Amersham. Melatonin was purchased from Sigma. Normal rabbit gamma globulin was purchased from Cappel Laboratories (Cochranville...

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Section: Discussionsupporting

confidence: 59%

“…The melatonin content of chicken pineals oscillates in a circadian fashion (7,8) and contributes to a rhythm of melatonin in the serum (9). The synthesis of melatonin in the chicken pineal appears to be regulated by the activity of the enzyme serotonin N-acetyltransferase (7), which oscillates with a circadian period in vivo (10).…”

mentioning

confidence: 99%

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Takahashi

Hamm

Menaker

1980

Proc. Natl. Acad. Sci. U.S.A.

222

104

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“…3) In mammals, the sympathetic fibres innervating the pin eal gland release NOR, which in turn stimulates MEL for mation via (l-adrenergic receptors on the pinealocyte mem brane [1]. However, in birds MEL synthesis is not depend ent on the sympathetic nervous system [22] and is not regulated by a [3-adrenergic mechanism [3]. It is therefore surprising that our results show an alteration in the electri cal activity of many of the pineal cells of the pigeons to the application of NOR.…”

Section: Effects O F Putative Transmitter Substancesmentioning

confidence: 99%

“…We have therefore investigated the effects of lo cal application of MEL and related pineal indoles, and >f noradrenaline (NOR), acetylcholine (ACH) and GABA i n the electrical activity of pineal cells in the pigeon. In birds, MEL synthesis and release show a circadian rhythm, per sisting under conditions of constant darkness [22], and re cently the avian pineal gland has been regarded as a self sustained circadian oscillator [36], In view of this, we have compared the effects of putative regulating substances on the glands of both intact and blinded birds.…”

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confidence: 99%

Electrical Responses of Pineal Cells to Pineal Indoles and Putative Transmitters in Intact and Blinded Pigeons

Demaine¹,

Semm²

1984

Neuroendocrinology

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The effects of micro-electrophoretically applied pineal indoles, melatonin (MEL), 5-methoxytryptophol (MTL) and 5-hydroxytryptophol (HTL) and of the neurotransmitters, noradrenaline (NOR), acetylcholine (ACH) and γ-aminobutyric acid (GABA) on the electrical activity of pineal cells were studied in anaesthetized pigeons. Recordings were made from both sighted and blinded birds during both the day- and night-time. Both excitatory and inhibitory responses to the application of all substances tested were observed, while in all cases unresponsive cells were also found. The pattern of responses to MEL, MTL and to NOR varied significantly depending on whether the cells in the sighted pigeons were tested during the day or at night. This day/night rhythm of responses to MEL and to MTL also occurred in the blinded pigeons, although this was not the case for the effects of NOR. Units which were orthodromically excited by electrical stimulation of the habenular complex were also excited by application of GABA. The activity of these units was also likely to be enhanced by application of ACH. The results suggest that the pigeon pineal organ exhibits intrinsic circadian rhythmicity which does not require entrainment signals from the retina. They also indicate that the activity of pineal cells could be influenced by neurotransmitter input provided from within the gland or via its innervation.

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“…As strong immunoreactivity to N-acetylindole antiserum is found in the cerebellum adjacent to Purkinje cells (Bubenik et al 1974) and as there are indications that the locomotor rhythm may be influenced by the pineal gland (Ralph et al 1974(Ralph et al , 1975 it was decided to study the effects of pineal indoleamines and pinealectomy on the spontaneous electrical activity of Purkinje cells and other units in the cerebellum. For comparison with other studies (see Discussion), noradrenaline (NA) was also administered.…”

Section: Introductionmentioning

confidence: 99%

Electrical responses of homing pigeon and guinea pig Purkinje cells to pineal indoleamines applied by microelectrophoresis

Semm

Vollrath

1984

J. Comp. Physiol.

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Summary. The effects of microelectrophoretically applied melatonin (aMT), 5-methoxytryptophol (ML), 5-hydroxytryptophol (HL) and noradrenaline (NA) on the electrical activity of cerebellar Purkinje and other cells during both day-and nighttime were studied in urethane-anesthetized intact and pinealectomized homing pigeons and guinea pigs.In the intact pigeon, equal numbers of Purkinje cells were excited and inhibited by aMT and ML, whilst the responses to HL were predominantly inhibitory. The responses varied significantly depending on whether the cells were tested during the day or at night (P < 0.001). Pinealectomy abolished the observed day/night differences. In intact pigeons most of the other cerebellar units were inhibited by aMT and ML, whilst HL elicited an excitation in about 50% of the units.In the guinea pig most of the Purkinje cells were inhibited by aMT and ML, whereas HL caused no response in most of the units. No significant 24-h rhythmicity in response to the indoles could be observed. The responses of the other cerebellar units were more complicated, aMT caused an excitation in most of the units, whilst the predominant response caused by ML was inhibition. Only 30% of these units responded to HL; the remainder showed no measurable responses.It is apparent from these studies that pineal indoleamines may play a modulatory role in the cerebellum.Abbreviations: ECG electrocardiogram; GABA gamma-aminobutyric acid; further abbreviations see Summary * Present address:

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Persistent Rhythms of Pineal and Serum Melatonin in Cockerels in Continuous Darkness

Cited by 43 publications

References 8 publications

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Electrical Responses of Pineal Cells to Pineal Indoles and Putative Transmitters in Intact and Blinded Pigeons

Electrical responses of homing pigeon and guinea pig Purkinje cells to pineal indoleamines applied by microelectrophoresis

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