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

Abstract

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...

Analysis of period mRNA cycling in Drosophila head and body tissues indicates that body oscillators behave differently from head oscillators.

“…There is precedent for both autonomous pacemakers and slave oscillators. In vitro cultures of gypsy moth testes (8), Xenopus eyes (4), chicken pineal glands (32), and Aplysia eyes (16) show that autonomous, light-entrainable pacemakers control free-running rhythms of sperm release (moth testes), melatonin release (Xenopus eyes and chicken pineal glands), and electrical activity (Aplysia eyes). Transplantation experiments show that an autonomous pacemaker in the Drosophila brain (11) and the hamster suprachiasmatic nucleus (26) sets the period of free-running activity rhythms.…”

Rhythmic Expression of Adenylyl Cyclase VI Contributes to the Differential Regulation of Serotonin N-Acetyltransferase by Bradykinin in Rat Pineal Glands

“…1B). The concentration dependence curve discloses maximal and half-maximal effective con- 3 induces Ca 2ϩ mobilization from intracellular stores through specific receptors, we measured the IP 3 generated as a result of BK treatment. Fig.…”

“…Melatonin synthesis is modulated by the hypothalamic circadian clock in the suprachiasmatic nucleus as well as light signals through a multisynaptic neuronal pathway projecting from the retina to the suprachiasmatic nucleus of the anterior hypothalamus via the retinohypothalamic tract (2). A dark signal perceived by the retina triggers norepinephrine release from postganglionic neurons originating in the superior cervical ganglion regulated by suprachiasmatic nucleus activation (3,4). Norepinephrine interacts with the ␤-adrenergic receptor on pinealocytes, inducing an increase in pineal cAMP generation.…”

Molecular basis for regulating seasonal reproduction in vertebrates

“…This is analogous to the functional differences in the pineal gland for circadian systems. The mammalian pineal gland is an endocrine organ that synthesizes and releases melatonin under the control of photic input from the retina and the circadian clock in the SCN (Morin et al 1977), whereas the pineal gland of nonmammalian species contains an entire circadian clock system consisting of the input (photoreceptor), oscillator (circadian clock), and output (synthesis and release of melatonin) (Takahashi et al 1980, Menaker & Wisner 1983. It is interesting to note that a recent developmental study identified common transcription factors in the SV and pituitary gland of rainbow trout (Maeda et al 2015).…”