Expression of melatonin receptors in arteries involved in thermoregulation

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.87.16.6200· OSTI ID:6445729

Viswanathan, M; Laitinen, J T; Saavedra, J M ^[1]

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1. National Institute of Mental Health, Bethesda, MD (USA)

Melatonin binding sites were localized and characterized in the vasculature of the rat by using the melatonin analogue 2-(125I)iodomelatonin (125I-melatonin) and quantitative in vitro autoradiography. The expression of these sites was restricted to the caudal artery and to the arteries that form the circle of Willis at the base of the brain. The arterial 125I-melatonin binding was stable, saturable, and reversible. Saturation studies revealed that the binding represented a single class of high-affinity binding sites with a dissociation constant (Kd) of 3.4 x 10(-11) M in the anterior cerebral artery and 1.05 x 10(-10) M in the caudal artery. The binding capacities (Bmax) in these arteries were 19 and 15 fmol/mg of protein, respectively. The relative order of potency of indoles for inhibition of 125I-melatonin binding at these sites was typical of a melatonin receptor: 2-iodomelatonin greater than melatonin greater than N-acetylserotonin much much greater than 5-hydroxytryptamine. Norepinephrine-induced contraction of the caudal artery in vitro was significantly prolonged and potentiated by melatonin in a concentration-dependent manner, suggesting that these arterial binding sites are functional melatonin receptors. Neither primary steps in smooth muscle contraction (inositol phospholipid hydrolysis) nor relaxation (adenylate cyclase activation) were affected by melatonin. Melatonin, through its action on the tone of these arteries, may cause circulatory adjustments in these arteries, which are believed to be involved in thermoregulation.

• OSTI ID: 6445729
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 87:16; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
AMINES
AROMATICS
ARTERIES
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL LOCALIZATION
BLOOD VESSELS
BODY
BODY TEMPERATURE
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CEREBRAL ARTERIES
CONTROL
CPB
DAYS LIVING RADIOISOTOPES
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HETEROCYCLIC COMPOUNDS
INDOLES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
MELATONIN
MEMBRANE PROTEINS
MUSCLES
NEUROREGULATORS
NORADRENALINE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
PYRROLES
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SYMPATHOMIMETICS
TEMPERATURE CONTROL
THERMOREGULATION
TRYPTAMINES