Identification of central 5-HT and 5-HT1A receptors in the turtle brain (Chrysemys picta).
Radiologand binding studies were undertaken in the turtle whole brain, cerebellum and raphe using the selective radioligands [3H]5-hydroxytryptamine trifluoroacetate ([3H]5-HT) amd [3H]+/-8-hydroxy-2-(di-N-propylamino) tetralin hydrobromide ([3H]DPAT) to identify serotonin (5-HT) receptors and the specific 5-HT1A receptor subtype. Scatchard analysis identified a nanomolar affinity binding site for [3H]5-HT (12 nM) in turtle whole brain assays. A low affinity 5-HT1A site (102 nM) was also identified in turtle whole brain assays, with a higher affinity site noted in binding studies performed with tissue from the inferior raphe (20 nM). The difference in affinity for 5-HT receptors in reptilian versus mammalian brain may prove characteristic of lower vertebrate brains with implications for the physiologic effects of this neurotransmitter in the central nervous system.
Larson-Prior
L J
LJ
Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine 17033, USA. ljlp@neuro.hmc.psu.edu
Bushey
R M
RM
Maines
L W
LW
Lakoski
J M
JM
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D005260:Female; D008297:Male; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D014426:Turtles
D011985:Receptors, Serotonin; D012701:Serotonin