Presence of Melatonin in Plasma and Urine of Pinealectomized Rats<sup>1</sup>

Ozaki, Yoshisuke; Lynch, Harry J.

doi:10.1210/endo-99-2-641

Cited by 157 publications

(62 citation statements)

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“…A highly significant increase was seen in the dark phase, 20 h after lights on. Values are in the same range as those previously reported (Ozaki & Lynch, 1976;Pang, Brown, Grota, ) and benserazide-treated rats at 80 mg/kg (solid columns) are significant (P < 0.001-0.05); at 50 mg/kg (stippled column$) are significant (P < 0.001-0.01) except for 9 and 17 h after lights on. Significance levels were assessed by Student's t test, unpaired.…”

Section: Resultssupporting

confidence: 73%

DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

Arendt

Laud

et al. 1981

British J Pharmacology

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1Low doses (50 and 80 mg/kg) of benserazide (Ro4-4602), an aromatic amino acid decarboxylase inhibitor, markedly reduced 5-hydroxytryptamine and melatonin in the rat pineal gland without affecting hypothalamic 5-hydroxytryptamine. 2 This differential effect shows that inhibition of the pineal gland decarboxylase activity is possible, and confirms that the rat pineal gland is accessible to peripherally acting agents.

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Section: Resultssupporting

confidence: 73%

DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

Arendt

Laud

et al. 1981

British J Pharmacology

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“…within the range of the circulating levels of melatonin in rodents (Oaknin-Bendahan et al, 1992) and, therefore, could be a physiologically relevant process. Moreover, the ectopic production of melatonin by a variety of tissues is a well characterized phenomenon (Ozaki and Lynch, 1976;Kvetnoy and Yuzhakov, 1993) and may lead to local concentrations of the hormone at least one order of magnitude higher than the circulating levels (Shaw et al, 1989). The modulation by melatonin of the melanocyte response to a-MSH could be particularly strong if melatonin is produced by epidermal cells, thus increasing its concentration in the microenvironment of melanocytes.…”

Section: Discussionmentioning

confidence: 99%

Melatonin Antagonizes α‐Melanocyte‐Stimulating Hormone Enhancement of Melanogenesis in Mouse Melanoma Cells by Blocking the Hormone‐Induced Accumulation of the C Locus Tyrosinase

Valverde

Benedito

Solano

et al. 1995

European Journal of Biochemistry

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Melatonin was found to have a small inhibitory effect on tyrosinase activity and a slight stimulatory action on dopachrome tautomerase activity in B16 mouse melanoma cells. These effects were time and dose dependent, with the maximal response being observed after 24-48 h treatment and at concentrations of melatonin higher than the physiologic levels of the circulating hormone. Although these effects on the melanogenic activities were modest, incubation of melanocytes with melatonin prior to the addition of the melanotropin mediated a dramatic inhibition of a-melanocyte-stimulating-hormone-(a-MSH)-induced melanogenesis. This inhibitory effect was evident at melatonin concentrations as low as 10 nM. Inhibition was nearly total at 0.1 mM melatonin, even at high concentrations of a-MSH (1 pM).The inhibitory effect of melatonin on a-MSH stimulation of melanogenesis was investigated. Melatonin appeared to act at least at two stages. Pharmacological concentrations of melatonin diminished the number of a-MSH receptors to about 75% of the control values without an apparent effect on receptor affinity, as determined by receptor-binding studies using '251-[N-Leu4-~-Phe7]a-MSH as a probe. Physiological concentrations of melatonin also appeared to interfere with the intracellular events coupling increased CAMP levels and induction of the c locus tyrosinase, since it strongly inhibited the theophyllinemediated stimulation of melanogenesis. The inhibiton of tyrosinase stimulation was higher in the microsoma1 than in the melanosomal fractions of cells which were treated with melatonin, then exposed to either a-MSH (1 pM) or theophylline (1 mM), suggesting that one of the main effects of melatonin might be inhibition of the induction of tyrosinase de novo synthesis.Keywords : melatonin ; a-melanocyte-stimulating hormone ; tyrosinase ; tyrosinase-related proteins ; melanogenesis.Mammalian pigmentation is the result of melanin production by the epidermal melanocytes. Within melanocytes, melanin synthesis proceeds in specialized organelles, the melanosomes, through a series of coupled enzymic and chemical reactions (reviewed in Prota, 1992). The two initial steps of the pathway, rate-limiting hydroxylation of tyrosine to yield ~-3P-dihydroxyphenylalanine (L-Dopa) and L-Dopa oxidation to L-dopaquinone, are catalyzed by tyrosinase. These two reactions can also be catalyzed, although with lower efficiency, by the tyrosinaserelated protein-1 (TRP1; Jimenez et al., 1991 ; JimCnez-Cervantes et al., 1994) a protein encoded by the b Locus (Jackson, 1988). At least one other enzymic protein, dopachrome tautomerase (Aroca et al., 1990), has been shown to be involved in regulation of the pathway. This enzyme catalyzes the tautomerization of L-dopachrome, the product of spontaneous evolution

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“…In mammals, most of the nocturnal rhythm in circulating melatonin is abolished by pinealectomy (Simonneaux and Ribelayga, 2003). However, sporadic reports suggested that as much as 20% of circulating melatonin is derived from tissues other than the pineal gland (Ozaki and Lynch, 1976).…”

Section: A Melatonin Physiology and Functionmentioning

confidence: 99%

International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, Classification, and Pharmacology of G Protein-Coupled Melatonin Receptors

et al. 2010

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Presence of Melatonin in Plasma and Urine of Pinealectomized Rats¹

Cited by 157 publications

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DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

Melatonin Antagonizes α‐Melanocyte‐Stimulating Hormone Enhancement of Melanogenesis in Mouse Melanoma Cells by Blocking the Hormone‐Induced Accumulation of the C Locus Tyrosinase

International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, Classification, and Pharmacology of G Protein-Coupled Melatonin Receptors

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Presence of Melatonin in Plasma and Urine of Pinealectomized Rats1

Cited by 157 publications

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DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

DIFFERENTIAL EFFECT OF BENSERAZIDE (Ro4‐4602) ON THE CONCENTRATION OF INDOLEAMINES IN RAT PINEAL AND HYPOTHALAMUS

Melatonin Antagonizes α‐Melanocyte‐Stimulating Hormone Enhancement of Melanogenesis in Mouse Melanoma Cells by Blocking the Hormone‐Induced Accumulation of the C Locus Tyrosinase

International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, Classification, and Pharmacology of G Protein-Coupled Melatonin Receptors

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Presence of Melatonin in Plasma and Urine of Pinealectomized Rats¹