Characterization of serotonin binding sites in insect ( Locusta migratoria) brain

• Published in: Insect biochemistry and molecular biology Vol. 23; no. 2; pp. 303 - 307
• Main Authors: Hiripi, Laszló, Downer, Roger G.H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1993; Elsevier Science
• Subjects: [ 3H]Ketanserin; [ 3H]Mianserin; [ 3H]Serotonin; Acrididae; binding sites; Biochemistry. Physiology. Immunology; Biological and medical sciences; Brain; Fundamental and applied biological sciences. Psychology; Insect; Insecta; Invertebrates; Locusta migratoria; Locusta migratoria migratorioides; Orthoptera; Physiology. Development; Receptor; receptors; serotonin; Brain; [ 3H]Mianserin; Receptor; Insect; [ 3H]Ketanserin; [ 3H]Serotonin; Ligand binding; Serotoninergic receptor; Serotonin; Insecta; Orthoptera; Central nervous system; Locusta migratoria; Binding site; Acrididae; Arthropoda; Neuromediator; Acridoidea; Kinetics; Invertebrata; Brain (vertebrata)
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/0965-1748(93)90012-H

Radioligand binding studies using [ 3H]serotonin, [ 3H]ketanserin and [ 3H]mianserin were used to characterize 5HT receptor sites in membrane preparations from the brain of the locust, Locusta migratoria migratorioides. The [ 3H]serotonin binds reversibly to brain membrane preparations with high affinity and the receptor has 5HT 1 characteristics. However, studies with specific antagonists suggest that the receptor differs pharmacologically from the 5HT 1 receptor subtypes which have been identified in vertebrate brain. Scatchard analysis indicates that the binding sites have a single component with a dissociation constant of 2.98±0.19nM and B max value of 14.45±1.12 pmol/g tissue. Serotonin, bufotenin, N, N-dimethyltryptamine, d-LSD, BOL are equipotent displacers of [ 3H]serotonin binding. Several other potential agonists and antagonists were tested and shown to effect varying degrees of inhibition. Ca and Mg ions have no significant effect on the [ 3H]serotonin binding; however, guanine nucleotides modulate the binding suggesting that G-protein is involved in the serotonin action. No specific, saturable ketanserin binding was found, thus indicating lack of a vertebrate-like 5HT 2 receptor. [ 3H]Mianserin binds to the brain membrane; however, the pharmacology of mianserin binding suggests that mianserin binds to an octapamine-rather than a serotonin-receptor.