title: Crosstalk Among Disrupted Glutamatergic and Cholinergic Homeostasis and Inflammatory Response in Mechanisms Elicited by Proline in Astrocytes.
abstract: Hyperprolinemias are inherited disorder of proline (Pro) metabolism. Patients affected may present neurological manifestations, but the mechanisms of neural excitotoxicity elicited by hyperprolinemia are far from being understood. Considering that the astrocytes are important players in neurological disorders, the aim of the present work was to study the effects 1 mM Pro on glutamatergic and inflammatory parameters in cultured astrocytes from cerebral cortex of rats, exploring some molecular mechanisms underlying the disrupted homeostasis of astrocytes exposed to this toxic Pro concentration. We showed that cortical astrocytes of rats exposed to 1 mM Pro presented significantly elevated extracellular glutamate and glutamine levels, suggesting glutamate excitotoxicity. The excess of glutamate elicited by Pro together with increased glutamate uptake and upregulated glutamine synthetase (GS) activity supported misregulated glutamate homeostasis in astrocytic cells. High Pro levels also induced production/release of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. We also evidenced misregulation of cholinergic anti-inflammatory system with increased acetylcholinesterase (AChE) activity and decreased acetylcholine (ACh) levels, contributing to the inflammatory status in Pro-treated astrocytes. Our findings highlighted a crosstalk among disrupted glutamate homeostasis, cholinergic mechanisms, and inflammatory cytokines, since ionotropic (DL-AP5 and CNQX) and metabotropic (MCPG and MPEP) glutamate antagonists were able to restore the extracellular glutamate and glutamine levels; downregulate TNFα and IL6 production/release, modulate GS and AChE activities; and restore ACh levels. Otherwise, the non-steroidal anti-inflammatory drugs nimesulide, acetylsalicylic acid, ibuprofen, and diclofenac sodium decreased the extracellular glutamate and glutamine levels, downregulated GS and AChE activities, and restored ACh levels in Pro-treated astrocytes. Altogether, our results evidence that the vulnerability of metabolic homeostasis in cortical astrocytes might have important implications in the neurotoxicity of Pro.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil. emaildasamanta@yahoo.com.br.
authors.forename: Samanta Oliveira
authors.initials: SO
authors.lastname: Loureiro
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Daniele Susana Volkart
authors.initials: DSV
authors.lastname: Sidegum
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Helena
authors.initials: H
authors.lastname: Biasibetti
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Mery Stefani Leivas
authors.initials: MSL
authors.lastname: Pereira
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Diogo Losch
authors.initials: DL
authors.lastname: de Oliveira
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Regina
authors.initials: R
authors.lastname: Pessoa-Pureur
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Angela T S
authors.initials: ATS
authors.lastname: Wyse
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology; D002794:Choline / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects*; D007249:Inflammation / Q000378:metabolism* / Q000473:pathology*; D011392:Proline / Q000494:pharmacology*; D017208:Rats, Wistar
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016207:Cytokines; D005973:Glutamine; D018698:Glutamic Acid; D011392:Proline; D000110:Acetylcholinesterase; D005974:Glutamate-Ammonia Ligase; D002794:Choline
keywords: Acetylcholine; Acetylcholinesterase; Astrocyte; Cholinergic system; Cytokine mediators; Excitotoxicity; Glutamate; Glutamine synthetase; IL-1β; IL-6; Inflammation; Proline; TNF-α