Modulation of Corpus Striatal Neurochemistry by Astrocytes and Vasoactive Intestinal Peptide (VIP) in Parkinsonian Rats.
The neurotoxin 6-hydroxydopamine (6-OHDA) is widely used in animal models of Parkinson's disease. In various neurodegenerative diseases, astrocytes play direct, active, and critical roles in mediating neuronal survival and functions. Vasoactive intestinal peptide (VIP) has neurotrophic actions and modulates a number of astrocytic activities. In this study, the effects of VIP on the striatal neurochemistry were investigated in parkinsonian rats. Adult Sprague-Dawley rats were divided into sham-operated, unilaterally 6-OHDA-lesioned, and lesioned + VIP-administered (25 ng/kg i.p.) groups. VIP was first injected 1 h after the intrastriatal 6-OHDA microinjection and then every 2 days throughout 15 days. Extracellular striatal concentration of glutathione (GSH), gamma-aminobutyric acid (GABA), glutamate (GLU), and lactate were measured in microdialysates by high-performance liquid chromatography (HPLC). Quantification of GABA and activity dependent neuroprotective protein (ADNP)-expressing cells were determined by glutamic acid decarboxylase (GAD)/ADNP + glial fibrillary acidic protein (GFAP) double immunohistochemistry. Our results demonstrated that a 6-OHDA lesion significantly increased the density of astrocytes in the striatum and VIP treatment slightly reduced the gliosis. Extracellular concentration of GABA, GLU, and lactate levels did not change, but GSH level significantly increased in the striatum of parkinsonian rats. VIP treatment reduced GSH level comparable to sham-operated groups, but enhanced GABA and GLU levels. Our double labeling results showed that VIP primarily acts on neurons to increase ADNP and GAD expression for protection. These results suggest that, in the 6-OHDA-induced neurodegeneration model, astrocytes were possibly activated for forefront defensiveness by modulating striatal neurochemistry.
Department of Physiology and Neurophysiology, Medical Faculty, Eskisehir Osmangazi University, 26040, Eskişehir, Turkey.
İbrahim Halil
İH
Yelkenli
Department of Anatomy, Medical Faculty, Eskisehir Osmangazi University, Eskisehir, Turkey.
Emel
E
Ulupinar
Department of Physiology and Neurophysiology, Medical Faculty, Eskisehir Osmangazi University, 26040, Eskişehir, Turkey.
Orhan Tansel
OT
Korkmaz
Department of Analytical Chemistry, Pharmacy Faculty, Anadolu University, Eskisehir, Turkey.
Erol
E
Şener
Department of Health Program, Open Faculty, Anadolu University, Eskisehir, Turkey.
Gökhan
G
Kuş
Department of Statistics, Science and Art Faculty, Eskişehir Osmangazi University, Eskisehir, Turkey.
Zeynep
Z
Filiz
Department of Physiology and Neurophysiology, Medical Faculty, Eskisehir Osmangazi University, 26040, Eskişehir, Turkey. ntuncel@ogu.edu.tr.
Neşe
N
Tunçel
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D003342:Corpus Striatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005911:Gliosis; D005968:Glutamate Decarboxylase / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D016627:Oxidopamine / Q000633:toxicity; D010300:Parkinson Disease / Q000209:etiology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
C579795:ADNP protein, rat; C000614142:Gfap protein, rat; D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; D019344:Lactic Acid; D014660:Vasoactive Intestinal Peptide; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D016627:Oxidopamine; D005968:Glutamate Decarboxylase; D005978:Glutathione
ADNP (activity dependent neuroprotective protein); Astrocyte; GABA (gamma-aminobutyric acid); GSH (glutathione); Parkinson’s disease; VIP (vasoactive intestinal peptide)