Modulation of the mesolimbic dopaminergic system by beta-endorphin-(1-27) as assessed by microdialysis. 1991

R Spanagel, and A Herz, and T S Shippenberg
Department of Neuropharmacology, Max-Planck-Institut für Psychiatrie, Martinsried, F.R.G.

In the present study we used in vivo microdialysis to examine the influence of beta-endorphin-(1-27) (beta-EP-(1-27) upon beta-endorphin (beta-EP)-induced dopamine (DA) release in the nucleus accumbens of anesthetized rats. Microdialysis probes were inserted into the nucleus accumbens and perfusates were analyzed for DA and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), using a reversed-phase HPLC system with electrochemical detection. Intracerebroventricular (i.c.v.) administration of beta-EP-(1-27) (5-20 micrograms) resulted in a dose-dependent increase in DA release which was smaller than the beta-EP-induced DA release, whereas metabolite levels were not altered. Pretreatment with beta-EP-(1-27) (5-20 micrograms) significantly altered the beta-EP (5 micrograms)-induced increase in DA release. These results indicate that beta-EP-(1-27) antagonizes the beta-EP-induced release of DA in the nucleus accumbens. In addition to its antagonistic properties at the beta-endorphin binding site, beta-EP-(1-27) appears to be a partial agonist, inducing increased DA release. These findings suggest a regulatory function for this naturally occurring beta-EP fragment within the mesolimbic system.

UI MeSH Term Description Entries
D007276 Injections, Intraventricular Injections into the cerebral ventricles. Intraventricular Injections,Injection, Intraventricular,Intraventricular Injection
D008032 Limbic System A set of forebrain structures common to all mammals that is defined functionally and anatomically. It is implicated in the higher integration of visceral, olfactory, and somatic information as well as homeostatic responses including fundamental survival behaviors (feeding, mating, emotion). For most authors, it includes the AMYGDALA; EPITHALAMUS; GYRUS CINGULI; hippocampal formation (see HIPPOCAMPUS); HYPOTHALAMUS; PARAHIPPOCAMPAL GYRUS; SEPTAL NUCLEI; anterior nuclear group of thalamus, and portions of the basal ganglia. (Parent, Carpenter's Human Neuroanatomy, 9th ed, p744; NeuroNames, http://rprcsgi.rprc.washington.edu/neuronames/index.html (September 2, 1998)). Limbic Systems,System, Limbic,Systems, Limbic
D008297 Male Males
D009714 Nucleus Accumbens Collection of pleomorphic cells in the caudal part of the anterior horn of the LATERAL VENTRICLE, in the region of the OLFACTORY TUBERCLE, lying between the head of the CAUDATE NUCLEUS and the ANTERIOR PERFORATED SUBSTANCE. It is part of the so-called VENTRAL STRIATUM, a composite structure considered part of the BASAL GANGLIA. Accumbens Nucleus,Nucleus Accumbens Septi,Accumbens Septi, Nucleus,Accumbens Septus, Nucleus,Accumbens, Nucleus,Nucleus Accumbens Septus,Nucleus, Accumbens,Septi, Nucleus Accumbens,Septus, Nucleus Accumbens
D010446 Peptide Fragments Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques. Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D003956 Dialysis A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Dialyses
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001615 beta-Endorphin A 31-amino acid peptide that is the C-terminal fragment of BETA-LIPOTROPIN. It acts on OPIOID RECEPTORS and is an analgesic. Its first four amino acids at the N-terminal are identical to the tetrapeptide sequence of METHIONINE ENKEPHALIN and LEUCINE ENKEPHALIN. Endorphin, beta,beta-Endorphin (1-31),beta Endorphin
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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