Pineal glands of immature rats: Rise and fall in <i>N</i>‐Acetyltransferase activity <i>in vitro</i>

Brammer, Mildred; Binkley, Sue

doi:10.1002/neu.480120206

Cited by 12 publications

(3 citation statements)

References 19 publications

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“…My conclusion, however, is in contrast to that of Brammer (1979), who postulated an endogenous time-keeping system in immature rat pineals. After this study was completed, Brammer and Binkley (1981) There are many differences in the N-acetyltransferase rhythms between immature rat pineals and chicken pineals. (1) Ganglionectomy or pretreatment with reserpine or I-propranolol abolished the N-acetyltransferase rhythm in immature rat pineals but not in chicken pineals Deguchi, 1 9 7 9~) . ( 2 ) Injection of catecholamines into animals or inclusion of catecholamines in culture medium markedly elevated N-acetyltransferase activity in immature rat pineals but not in chicken pineals Deguchi, 1 9 7 9~) .…”

Section: Discussionmentioning

confidence: 99%

“…There is one difference in the pineal Nacetyltransferase rhythms between adult and infant rats. Immature rat pineals showed a spontaneous increase of the enzyme activity in organ culture, whereas the activity in adult rat pineals did not increase in organ culture (Deguchi and Axelrod, 1973;Holz et al, 1974;Brammer and Binkley, 1981). Two possibilities are conceivable as to the difference between adult and infant rat pineals.…”

Section: ( 5 )mentioning

confidence: 98%

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Sympathetic Regulation of Circadian Rhythm of Serotonin N‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Deguchi

1982

Journal of Neurochemistry

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The circadian rhythms of serotonin N-acetyltransferase activity in the pineal glands of infant and adult rats were compared. The nighttime increase of N-acetyltransferase activity in the pineals of infant rats was blocked by removal of superior cervical ganglion or by pretreatment with reserpine, l-propranolol, and cycloheximide. Injection of isoproterenol to infant rats markedly elevated pineal N-acetyltransferase activity. When the pineal glands of infant rats were organ-cultured, N-acetyltransferase activity spontaneously increased 7--12 h after the rats were killed. When infant rats were previously denervated or pretreated with reserpine and their pineals were cultured, this spontaneous elevation of N-acetyltransferase activity was abolished, indicating that the transient increase of the enzyme activity in organ culture was due to a liberation of catecholamine from degenerating nerve endings. Additional illumination until midnight prevented the nighttime increase of N-acetyltransferase activity in intact infant rats but not in blinded infant rats. These observations are taken to indicate that N-acetyltransferase rhythm in immature rat pineals is regulated by the sympathetic nerves in the same manner as in adult rat pineals, that the immature rat pineal does not contain a time-keeping system, and that there is no extraretinal light perception in infant rats as far as N-acetyltransferase rhythm is concerned.

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Section: Discussionmentioning

confidence: 99%

Section: ( 5 )mentioning

confidence: 98%

Sympathetic Regulation of Circadian Rhythm of Serotonin N‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Deguchi

1982

Journal of Neurochemistry

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“…Regulation of the melatonin-forming enzyme serotonin N-acetyltransferase (NAT) has been demonstrated in blinded neonatal rats in some studies (Torres and Lytle, 1990), but not in others (Deguchi, 1982b;Reppert et al, 1984). It has not proved feasible to demonstrate light-induced electrophysiological changes in dissociated rat pinealocytes nor modulation of melatonin production in neonatal pineal cultures (Brammer and Binkley, 1981).…”

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confidence: 99%

Developmental Expression Pattern of Phototransduction Components in Mammalian Pineal Implies a Light-Sensing Function

1997

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Whereas the pineal organs of lower vertebrates have been shown to be photosensitive, photic regulation of pineal function in adult mammals is thought be mediated entirely by retinal photoreceptors. Extraretinal regulation of pineal function has been reported in neonatal rodents, although both the site and molecular basis of extraretinal photoreception have remained obscure. In this study we examine the developmental expression pattern of all of the principal components of retinal phototransduction in rat pineal via cRNA in situ hybridization. All of the components needed to reconstitute a functional phototransduction pathway are expressed in the majority of neonatal pinealocytes, although the expression levels of many of these genes decline dramatically during development. These findings strongly support the theory that the neonatal rat pineal itself is photosensitive. In addition, we observe in neonatal pinealocytes the expression of both rod-specific and cone-specific phototransduction components, implying the existence of functionally different subtypes of pinealocytes that express varying combinations of phototransduction enzymes.

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The rise and fall of pineal N‐acetyltransferase in vitro: Neural regulation in the developing rat

1982

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In rats, the pineal gland has a rhythm in the activity of the enzyme, N-acetyltransferase (NAT), which is thought responsible for daily cycles of melatonin synthesis. Neonatal rat pineal glands, but not those of adult rats, have a single cycle that is observed in vitro during the first day of organ culture. The neural regulation of the cycle was investigated using neonatal rats with adult rats used for comparison. Prior treatment of rat pups with constant light did not abolish the cycle in vitro though it did abolish the in vivo rhythm. Removal of the superior cervical ganglia did not abolish the in vivo rhythm that was measured the first day after surgery, but ablation of the ganglia did abolish the rhythm if several days or more elapsed after surgery. Extirpation of the superior cervical ganglia abolished the in vitro NAT cycle in pup pineal glands as did the pharmacological equivalent, injection of 6-hydroxydopamine. Propranolol, a beta blocking agent, prevented the occurrence of the cycle in vitro.

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Pineal glands of immature rats: Rise and fall in N‐Acetyltransferase activity in vitro

Cited by 12 publications

References 19 publications

Sympathetic Regulation of Circadian Rhythm of Serotonin N‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Sympathetic Regulation of Circadian Rhythm of Serotonin N‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Developmental Expression Pattern of Phototransduction Components in Mammalian Pineal Implies a Light-Sensing Function

The rise and fall of pineal N‐acetyltransferase in vitro: Neural regulation in the developing rat

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