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Serotonin 5‐HT 1A receptor expression is selectively enhanced in the striosomal compartment of chronic parkinsonian monkeys
Author(s) -
Frechilla Diana,
Cobreros Almudena,
Saldise Laura,
Moratalla Rosario,
Insausti Ricardo,
Luquin MRosario,
Del Río Joaquín
Publication year - 2001
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/1098-2396(20010315)39:4<288::aid-syn1011>3.0.co;2-v
Subject(s) - mptp , striatum , putamen , serotonergic , raphe nuclei , medicine , serotonin , endocrinology , 5 ht receptor , dopaminergic , neuroscience , 5 ht1a receptor , biology , caudate nucleus , receptor , dopamine
Cynomolgus monkeys ( Macaca fascicularis ) were chronically treated with the dopaminergic neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) until stable parkinsonism was reached. Two months later, monkeys were sacrificed and monoamine content was measured in different brain regions of the lesioned monkeys and of age‐matched controls. 5‐HT 1A serotonin receptor density was measured in coronal sections labeled with [ 3 H]8‐OH‐DPAT. As expected, dopamine was virtually nonexistent in the caudate nucleus and putamen of MPTP‐treated monkeys. Serotonin levels were significantly reduced in different brain regions, particularly in the raphe nuclei. 5‐HT 1A receptor density of control animals was high in the hippocampus, notably in the CA1 field and also in the raphe nuclei, and much lower in the striatum, where 5‐HT 1A receptors showed a patchy distribution which corresponded to striosomes with poor calbindin immunostaining. 5‐HT 1A receptor density was reduced in hippocampal fields and in the raphe nuclei of parkinsonian monkeys. Conversely, in the severely lesioned striatal nuclei 5‐HT 1A receptor density was increased at caudal levels of the striatum, particularly in the putamen. The results tend to support the possibility of an increased synthesis of 5‐HT 1A receptors in brain regions with higher neuronal cell death. Upregulation of this 5‐HT receptor subtype in the limbic compartment of the striatum may represent a compensatory event for the serotonergic dysfunction and associated mental disorders in neurodegenerative diseases such as Parkinson disease. Synapse 39:288–296, 2001. © 2001 Wiley‐Liss, Inc.