Aging and Diurnal Rhythms of Pineal Serotonin, 5-Hydroxyindoleacetic Acid, Norepinephrine, Dopamine and Serum Melatonin in the Male Rat

Tang, Florence; Hadjiconstantinou, Maria; Pang, S.F.

doi:10.1159/000124068

Cited by 42 publications

(14 citation statements)

References 30 publications

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“…The peak of DOPAC, delayed by 2 h with respect to the nadir of DA, reflects the deamination rate of DA. These data support previous studies showing circadian changes of catecholamine levels in some regions of rat brain [5, 6, 7, 9, 31, 32, 33], and show that pinealectomy and aMT replacement therapy influence the dopaminergic but not serotonergic system in the striatum. Although some reports point to an involvement of aMT in the 5-HT turnover in some brain areas in rats [34], the lack of interaction between aMT and 5-HT in the mouse striatum agrees with other studies [35].…”

Section: Discussionsupporting

confidence: 92%

Circadian Rhythms of Dopamine and Dihydroxyphenyl Acetic Acid in the Mouse Striatum: Effects of Pinealectomy and of Melatonin Treatment

et al. 2002

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The existence of dopamine (DA)-melatonin (aMT) relationships is well documented in several brain areas of the mammalian central nervous system such as the retina and hypothalamus or the nigrostriatal system. For instance, aMT tempers 1 methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced nigrostriatal damage in C57BL/6 mice. In this mouse strain however, rhythmic production of aMT and its possible interaction with striatal DA is still unclear. In the present work we investigated circadian variations in pineal production of aMT and striatal DA levels in C57BL/6 mice. Effects of pinealectomy and aMT administration were also assessed. Intact, pinealectomized and pinealectomized + aMT-treated mice and their respective control groups were sacrificed at six different times during the 24-hour period. In control animals, aMT displayed a circadian rhythm with a narrow peak at midnight. The peak of aMT coincided with the nadir of the DA rhythm present in the striatum. Shortly after the decrease of DA levels, an increase in 3,4-dihydroxyphenylacetic acid (DOPAC), the main DA metabolite, was observed. The rhythmic changes of DA and DOPAC levels in the striatum were blunted by pinealectomy, whereas administration of aMT (0.1–10 mg/kg) during 6 days to pinealectomized mice restored the rhythms in a dose-dependent manner. Striatal levels of 3-methoxytyramine and homovanillic acid did not change during the 24-hour cycle. The serotonergic system, assessed by the determination of 5-hydroxytryptamine and 5-hydroxyindole-3-acetic acid concentration in striatum, did not show significant time-dependent changes in control animals and was not affected by pinealectomy or aMT treatment. These data substantiate the existence of a link between pineal function, melatonin secretion and DA circadian rhythm in the mouse striatum.

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Section: Discussionsupporting

confidence: 92%

Circadian Rhythms of Dopamine and Dihydroxyphenyl Acetic Acid in the Mouse Striatum: Effects of Pinealectomy and of Melatonin Treatment

et al. 2002

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“…Day-night variations of pineal N E and DA content shown here are equivalent to those reported previously by using similar methodology (8,39). Diurnal rhythms of pineal catecholamine levels are probably due to the nocturnal increase of pineal sympathetic activity (4,5), which in turn causes the observed elevation of T H activity (6).…”

Section: Discussiorsupporting

confidence: 87%

Castration Reduces the Nocturnal Rise of Pineal Melatonin Levels in the Male Rat by Impairing its Noradrenergic Input

Hernández

Abreu

Alonso

et al. 1990

J Neuroendocrinology

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The effects of castration and testosterone treatment on pineal day-night rhythms were studied in male rats. Bilateral gonadectomy was performed at 21 days of age. Testosterone propionate was given subcutaneously to castrated animals in a dose of 10 pg/100 g body weight during two consecutive days before sacrifice. Animals were killed 40 days after gonadectomy at four different times of a 12:12 h light-dark cycle (1600, 2400, 0400 and 0800 h). Tyrosine hydroxylase activity was measured in individual pineals by means of high-performance liquid chromatography determination of L-DOPA formed. Pineal levels of norepinephrine, dopamine, 5-hydroxytryptamine and 5-hydroxyindole acetic acid were determined by high-performance liquid chromatography with amperometric detection, while pineal melatonin content was measured by radioimmunoassay. Castration abolished the day-night rhythms of pineal tyrosine hydroxylase activity and norepinephrine content, both by elevating their daytime levels and by blocking their nocturnal rise. In addition, gonadectomy drastically modified pineal indoleamine metabolism by increasing daytime levels of both 5-hydroxytryptamine and 5-hydroxyindole acetic acid, and by reducing the nocturnal elevation of pineal melatonin content. Testosterone treatment was unable to prevent the effect of orchidectomy on pineal rhythms of tyrosine hydroxylase activity, 5-hydroxytryptamine or 5-hydroxyindole acetic acid content, however it partially restored the day-night pineal rhythms of both norepinephrine and melatonin content. These results are indicative of a possible participation of reproductive hormones in the control of pineal rhythmic activity in the male rat. Apparently, since gonadectomy abolished the nocturnal rise of both pineal tyrosine hydroxylase activity and norepinephrine content, the primary site of action of reproductive hormones could be at the level of the superior cervical ganglion.

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“…Studies aimed at investigating the effect of aging on pineal indoleamines in rats indicated reductions in 5-HT and 5-HIAA content when assessed at two time points in the 24-hour cycle [10,12]. Our present study, including 6 time points throughout a 24-hour cycle, agrees with the existence of such a decrease in pineal 5-HT and 5-HIAA.…”

Section: Discussionsupporting

confidence: 86%

“…In aged rodents [9][10][11][12] and humans [13][14][15][16][17][18][19], decreases in pineal melatonin secretion have been documented. In addition, neuronal degeneration at the SCN [20] and a decrease in the number of pinealocytes [21] have been reported as a consequence of aging and could be relevant causes of age-related decreases in melatonin levels.…”

Section: Introductionmentioning

confidence: 99%

“…Age-associated decreases in rat pineal catecholamine and indoleamine levels have been documented, but generally on the basis of assessments at only two time points, i.e. the middle of the light and dark periods of the 24-hour cycle [10,12]. This percluded any conclusions regarding the possible changes in phase that may occur in pineal rhythms as a consequence of aging.…”

Section: Introductionmentioning

confidence: 99%

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Age-Related Changes in 24-Hour Rhythms of Norepinephrine Content and Serotonin Turnover in Rat Pineal Gland: Effect of Melatonin Treatment

Pazo¹,

Cardinali

Cano³

et al. 2002

Neurosignals

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The 24-hour rhythms of pineal norepinephrine (NE) content and serotonin (5-HT) turnover [estimated from the ratio of 5-hydroxyindoleacetic acid (5-HIAA) to 5-HT] were studied in young (2 months) and aged (18–20 months) Wistar rats killed at 6 different time points throughout a 24-hour cycle. In the first study, significant changes dependent on the time of day were identified, with acrophases in the first half of the activity span for both parameters. Old rats showed significantly smaller mesor and amplitude of the 24-hour rhythm of pineal NE content. They also showed decreased amplitude of the pineal 5-HT turnover rhythm, in the absence of changes in mesor. In old rats, pineal 5-HT and 5-HIAA concentrations were 41–47% of those found in young rats. In a second study, young and old rats received daily intraperitoneal injections of melatonin (30 µg) or vehicle for 11 days at 19.00 h (i.e. 11 h after light on). Analyzed as a main factor in a factorial analysis of variance, both pineal NE content and 5-HT turnover decreased in old rats while pineal 5-HT turnover increased after melatonin treatment. Melatonin treatment augmented the amplitude of the 24-hour rhythm of pineal NE content by 120 and 52% in young and old rats, respectively. The amplitude of the 24-hour rhythm of pineal 5-HT turnover almost doubled after melatonin treatment in young rats and did not change in old rats. Melatonin injection did not modify the rhythm’s acrophase. The results indicate that old rats had lower amplitude and lower mesor values of 24-hour variations in pineal NE content and 5-HT turnover. Melatonin treatment only partly restored pineal NE content and was devoid of activity on pineal 5-HT turnover and 5-HT and 5-HIAA concentration in old rats. Impairment of pineal melatonin synthesizing capacity and intrapineal responses to melatonin may underlie pineal aging in rats.

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Aging and Diurnal Rhythms of Pineal Serotonin, 5-Hydroxyindoleacetic Acid, Norepinephrine, Dopamine and Serum Melatonin in the Male Rat

Cited by 42 publications

References 30 publications

Circadian Rhythms of Dopamine and Dihydroxyphenyl Acetic Acid in the Mouse Striatum: Effects of Pinealectomy and of Melatonin Treatment

Circadian Rhythms of Dopamine and Dihydroxyphenyl Acetic Acid in the Mouse Striatum: Effects of Pinealectomy and of Melatonin Treatment

Castration Reduces the Nocturnal Rise of Pineal Melatonin Levels in the Male Rat by Impairing its Noradrenergic Input

Age-Related Changes in 24-Hour Rhythms of Norepinephrine Content and Serotonin Turnover in Rat Pineal Gland: Effect of Melatonin Treatment

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