Acute effects of unilateral or bilateral superior cervical ganglionectomy on rat pineal N-acetyltransferase activity and melatonin content

Reíter, Russel J.; Rudeen, P. K.; Banks, A. F.; Rollag, Mark D.

doi:10.1007/bf01960402

Cited by 41 publications

(13 citation statements)

References 15 publications

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“…The second hypothesized mechanism, an increase in sympathetic nerve activity on the intact side, might compensate for the lack oftransmitter release from the sectioned nerves. Although no evidence exists for such a change in nerve firing, an increase in neural activity might be triggered by the decrease in various sympathetic functions that occurs after unilateral ganglionectomy or unilateral cutting of the ICN (e.g., the decrease in melatonin secretion) (20). However, it is difficult to imagine why, if such a reflex existed, it would not also be activated by unilateral decentralization of the SCG because this procedure would be expected to lead to functional losses similar to those after unilateral ganglionectomy (Fig.…”

Section: Resultsmentioning

confidence: 99%

Rapid recovery of function after partial denervation of the rat pineal gland suggests a novel mechanism for neural plasticity.

Zigmond

Baldwin

Bowers

1981

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

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The activity of serotonin N-acetyltransferase (NATase) in the rat pineal gland exhibits a large (approximately 100-fold) circadian variation, with peak activity occurring in the dark part ofthe light/dark cycle. Surgical removal ofboth superior cervical ganglia abolishes this rhythm in enzyme activity. Unilateral ganglionectomy caused a 75% decrease in NATase activity during the dark period immediately following the operation; however, by the subsequent dark period (32 hr after operation) the rhythm in NATase activity had returned to normal. Similar results were found after the internal carotid nerve was cut, and data are presented indicating that this is the postganglionic trunk by which sympathetic neurons reach the pineal gland. Denervation of one superior cervical ganglion (unilateral "decentralization") also produced a 75% decrease in NATase activity during the dark period immediately following the operation; however, after decentralization, enzyme activity did not return to normal in subsequent cycles. It is hypothesized that this recovery is due to loss of norepinephrine uptake sites in the degenerating sympathetic nerve terminals. As a result of decreased norepinephrine uptake, the effectiveness of the norepinephrine released by surviving neurons may be enhanced. This hypothesis is supported by experiments in which pharmacological blockade of norepinephrine uptake in unilaterally decentralized animals increased NATase activity to control levels. We propose that neural systems which use transmitter uptake as the mechanism of transmitter inactivation have a built-in "reserve stimulatory capacity."Although a great deal of interest has been focused in recent years on the ability of the nervous system to recover after subtotal neural damage, there are only a few systems available in which functional recovery has been studied quantitatively on a cellular level. A useful system for such an investigation should have two characteristics: (i) permit the making of a lesion of a reproducible size in a specific part of the nervous system, and (ii) permit quantitative measurement ofthe degree offunctional recovery after the lesion is made. The innervation of the rat pineal gland offers such a model system.The pineal gland is a midline structure innervated by adrenergic sympathetic neurons whose cell bodies are located in the right and left superior cervical ganglia (SCGs) (1-4). In the rat these ganglia are the primary source ofneurons innervating this tissue (3)(4)(5). Ganglionic neurons are important in regulating a number of aspects of the biochemistry of the pineal parenchymal cells, particularly the synthesis of the. hormone melatonin. Pinealocytes synthesize melatonin from serotonin in two steps catalyzed by the enzymes serotonin N-acetyltransferase (arylamine N-acetyltransferase, EC 2.3.1.5) (NATase) and hydroxyindole O-methyltransferase (acetylserotonin methyltransferase, EC 2.1.1.4).The sympathetic neurons innervating the pineal gland appear to constitute the final pathway by which changes in environ...

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Section: Resultsmentioning

confidence: 99%

Rapid recovery of function after partial denervation of the rat pineal gland suggests a novel mechanism for neural plasticity.

Zigmond

Baldwin

Bowers

1981

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

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“…¿-propranolol) or depletion of pineal NE by adrenergic denervation of the gland (e.g. superior cervical ganglionectomy) inhibits the normal nighttime rise in melatonin synthesis [10,24). These denervation effects are reversed by ad ministration of a beta-adrenergic receptor agonist such as iso proterenol.…”

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confidence: 96%

Tryptophan Administration Inhibits Nocturnal N-Acetyltransferase Activity and Melatonin Content in the Rat Pineal Gland

Reíter¹,

King²,

Steinlechner³

et al. 1990

Neuroendocrinology

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In the rat pineal gland, the activity of serotonin N-acetyltransferase (NAT) and the concentration of melatonin are normally high at night; conversely, the concentration of serotonin (5-HT), the precursor of melatonin, is low. Since tryptophan administration increases the concentration of pineal 5-HT at night, we examined its effect of melatonin production. Nighttime tryptophan loading led to substantial increases in pineal 5-hydroxytryptophan, 5-hydroxyindole acetic acid (5-HIAA), and 5-HT but a highly significant reduction in NAT activity in comparison to saline-injected controls. In contrast to other measured indoles, melatonin levels also were significantly diminished by tryptophan loading. Nocturnally high pineal norepinephrine levels were unaltered by tryptophan administration. The idea that high concentrations of 5-HT could lead to substrate inhibition of NAT activity was not supported by kinetic analysis of control NAT levels versus tryptophan-inhibited NAT activity under varied substrate concentrations. Hypotheses to explain these results include the possibility that tryptophan inhibition of melatonin synthesis is mediated by the release of 5-HT from the pinealocyte and its subsequent autocrine action on melatonin production.

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“…The nocturnal rise in pineal melatonin content was com pletely blocked in rats with removal of the superior cervical gan glia [Reiter et al, 1979]. Since the pulsatile secretory pattern of pineal melatonin in the confluens sinuum of rabbits was af fected by electrical stimulation of the cervical sympathetic nerve [Chan et al, 1989a, b] and systemic administration of betaadrenergic agents [Cheung et al, 1988], The diurnal variation of pineal melatonin secretion during the light and dark phases of the 24-hour period [Chan et al, 1989a[Chan et al, , 1990 would be under the modulation of the sympathetic system.…”

Section: Sympathetic Influence On Pineal Melatonin Secretionmentioning

confidence: 99%

Rhythmic Release Pattern of Pineal Melatonin in Rodents

Chan¹,

Cheung²,

Pang³

1991

Neuroendocrinology

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The plasma melatonin in the confluens sinuum of anesthetized rabbits and rats exhibited an episodic release pattern, with pulses superimposed on a basal level. The rhythmicity of pineal melatonin release revealed by our experimental paradigm was dependent on the blood sampling interval. In rabbits, it was found that the plasma melatonin level in the confluens sinuum was 7–15 times higher than that obtained from the plasma collected at the same time from the peripheral artery where the melatonin level also showed a pulsatile pattern. Diurnal variation in pineal melatonin level in the confluens sinuum was observed only in acutely blinded rabbits and rats. Electrical stimulation of the unilateral cervical sympathetic trunk of rabbits resulted in elevation of the level of plasma melatonin in the confluens sinuum, while the frequency of pulse peaks of plasma melatonin revealed at 4-min intervals was not affected. Similar results were obtained in rabbits with systemic administration of beta-adrenergic agents. These findings suggest that the release of pineal melatonin into the confluens sinuum is under the regulation of the cervical sympathetic system. The sympathetic influence on pineal melatonin secretion seems to vary with age. Furthermore, age-related fluctuation of systemic blood melatonin appeared to be the results of changes in the rate of pineal melatonin secretion, body growth and ageing.

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Acute effects of unilateral or bilateral superior cervical ganglionectomy on rat pineal N-acetyltransferase activity and melatonin content

Cited by 41 publications

References 15 publications

Rapid recovery of function after partial denervation of the rat pineal gland suggests a novel mechanism for neural plasticity.

Rapid recovery of function after partial denervation of the rat pineal gland suggests a novel mechanism for neural plasticity.

Tryptophan Administration Inhibits Nocturnal N-Acetyltransferase Activity and Melatonin Content in the Rat Pineal Gland

Rhythmic Release Pattern of Pineal Melatonin in Rodents

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