ISSN:
1573-6830
Keywords:
pineal
;
catecholamines
;
adrenaline
;
noradrenaline
;
dopamine
;
stress
;
circadian rhythm
;
adrenal medulla
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. Acute immobilization stress results in an increase in pineal adrenaline levels, which is prevented by prior removal of the adrenal medulla, indicating that the adrenal medulla is the primary source of elevated adrenaline concentrations in the pineal gland during stress. 2. Adrenomedullectomy does not result in a decrease in the low pineal adrenaline levels observed in nonstressed rats. This finding, together with the presence in the pineal gland of the adrenaline-forming enzyme, phenylethanolamine-N-methyltransferase (PNMT; EC 2.1.1.28), indicates that local synthesis of small amounts of adrenaline can normally occur in the pineal gland. 3. The lack of change in methylating activity after denervation of the pineal gland suggests that adrenaline synthesis may normally occur postsynaptically. 4. No significant changes occur in the pineal concentrations of noradrenaline and dopamine after stress and adrenomedullectomy, with the exception of increased dopamine levels after stress in adrenomedullectomized rats. 5. Adrenaline concentrations show a 24-hr rhythm in the rat pineal gland, with maximum levels during the second half of the dark period (0100 to 0500 hr) and low concentrations at the end of the light period (1700 hr). The changes in pineal adrenaline levels parallel those of the other catecholamines, dopamine and noradrenaline, indicating that increased synthesis and/or uptake from the circulation of all three catecholamines can occur synchronously during the latter part of the dark period. 6. Our results suggest a physiological role for pineal adrenaline, together with dopamine and noradrenaline, in the regulation of the daily pineal rhythms and during stress.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00735062
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