Desmethylimipramine pretreatment prevents 6-hydroxydopamine induced somatostatin receptor reduction in the rat hippocampus
Identifiers
Permanent link (URI): http://hdl.handle.net/10017/2978DOI: 10.1016/0167-0115(92)90116-C
ISSN: 0167-0115
Publisher
Elsevier
Date
1992Funders
Ministerio de Educación y Ciencia
Instituto de Salud Carlos III
Bibliographic citation
Regulatory Peptides, 1992, v. 41, n. 3, p. 227-236
Keywords
6-Hydroxydopamine
Desmethylimipramine
Hippocampus
Rat
Somatostatin receptor
Project
info:eu-repo/grantAgreement/MEC//PM91-0027/ES/INFLUENCIA DE LOS SISTEMAS CATECOLAMINERGICO Y SEROTONINERGICO SOBRE EL MECANISMO DE ACCION DEL SISTEMA SOMATOSTATINERGICO CEREBRAL DE LA RATA
info:eu-repo/grantAgreement/ISCIII//88%2F0903/ES//
Document type
info:eu-repo/semantics/article
Version
info:eu-repo/semantics/publishedVersion
Publisher's version
http://dx.doi.org/10.1016/0167-0115(92)90116-CRights
© Elsevier B.V., 1992
Access rights
info:eu-repo/semantics/openAccess
Abstract
Several studies have shown anatomical and functional interconnections between catecholaminergic and somatostatinergic systems. To assess whether somatostatin (SS) may act presynaptically on catecholamine neurons, SS receptors were measured using radioligand test-tube binding assays on synaptosomes from hippocampus and frontoparietal cortex — areas that are innervated by catecholaminergic neurons with different densities and that have a high number of SS receptors — from control and 6-hydroxydopamine (6-OHDA)-treated rats. Intracerebroventricular (i.c.v.) injection of the catecholamine neurotoxin 6-OHDA (0.78 mg free base/kg of body weight in saline with 0.1% ascorbic acid) lowered hippocampal and frontoparietal cortical noradrenaline (NA) and dopamine (DA) levels at 1 week following the injection. Pretreatment of rats with desmethylimipramine (DMI) (40 mg/kg, intraperitoneal) prevented the drop in NA levels, but was not effective in attenuating DA depletion in the two brain areas studied. Treatment with 6-OHDA lowered the number of 125I-Tyr11-SS receptors in the hippocampus (130 ± 19 vs. , P < 0.001), whereas in the frontoparietal cortex a non significant 20% reduction in receptor number was found. The dissociation constants of 125I-Tyr11-SS binding to synaptosomes from frontoparietal cortex (0.65 ± 0.06 vs. 0.60 ± 0.04, P not significant) and hippocampus (0.44 ± 0.04 vs. 0.63 ± 0.14, P not significant) were similar in control and treated groups. Pretreatment with DMI reversed up to 80% of the effect of 6-OHDA on hippocampus SS receptors. DMI alone had no observable effect on the number and affinity of SS receptors. The 6-OHDA and the DMI treatment did not affect SLI levels in the brain areas studied. These results suggest that a portion of the hippocampal SS receptors may be localized presynaptically on the noradrenergic and dopaminergic nerve terminals.
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