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Institute of Science and Technology for Research and Development
 

  [3H] GBR 12935 DOPAMINE TRANSPORTER SITE  IN BOVINE PINEAL GLAND
  (NO. 938)

Pavinee Vilaipun1, Piyarat Govitrapong1, Banthit Chetsawang1, Naiphinich Kotchabhakdi and M.Ebadi2

1Neuro-Behavioral Biology Center, Institute of Science and Technology for Research and Development, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand; 2Department of Pharmacology, Physiology and Therapeutics, University of North Dakota, School of Medicine and Health Science, USA

Key words: dopamine transporter, serotonin, norepinephrine, pineal gland

                    The mammalian pineal glands contain several neurotransmitters and receptors for amino acids, biogenic amines, and peptides. Some of these, such as dopamine and D1 and D2 dopamine receptors, have been identified and characterized in bovine pineal gland. This leads us to hypothesize that this organ possesses a high-affinity dopamine transporter mechanism for dopamine substrate. This study is an attempt to investigate the existence of dopamine transporter in the bovine pineal gland. The radio-ligand used was [3H] GBR 12935 and the drug to define non-specific binding was GBR 12909. The association rate of [3H] GBR 12935 binding to pineal gland membranes was examined as a function of time. The binding reached equilibrium within 60 min of incubation at 25oC. Drugs that block the uptake of dopamine (GBR 12909, GBR 12395) were effectively in displacing [3H] GBR 12935 from bovine gland whereas drugs that block the uptake of serotonin (gluoxetine, fluvoxamine), norepinephrine (desipramine) and mixed reuptake inhibitor affecting serotonin and norepinephrine (imipramine, amitriptyline) were ineffective. The specific binding to bovine pineal membrane was higher than in rat striatum. The result of this study indicates that dopamine transporters are present in the bovine pineal gland.

Acknowledgement: This study was supported by National Institute of Neurological Disorders and Stroke, USA, 1RO1 NS-40160-1 grant.

(Presented at the 3rd International Congress of the Asian Sleep Research Society on the New Millennium of Sleep Research in Asia, December 3-7, 2000, Bangkok, Thailand, and published in the Program and Abstracts page A174.)