Effects of I2-imidazoline receptor (IR) alkylating BU99006 in the mouse brain: Upregulation of nischarin/I1-IR and μ-opioid receptor proteins and modulation of associated signalling pathways.
5-isothiocyanato-2-benzofuranyl-2-imidazoline (BU99006) was shown to selectively and irreversibly bind to I2-imidazoline receptors (IRs) in vitro and in vivo, but cell signalling consequences of I2-IR alkylation have not been reported previously. This study assessed by Western blot the effects of BU99006 on nischarin (candidate I1-IR), μ-OR (regulated by nischarin) and associated signalling mediators in the mouse brain. Acute treatment with BU99006 (20 mg/kg, i.p., 1-3 h) led to fast (peak at 1 h) and shortlasting (decline up to 3 h) upregulation of nischarin and μ-OR contents in the hippocampus (less or non-significant effects in cortex) and altered the expression of cytoskeletal β-actin (reduced contents at 3 h). In the same hippocampal samples of BU99006-treated mice, an inhibition of the MAPK species MEK, ERK and JNK was detected at 1 and/or 2 h after drug administration, which was paralleled by enhanced calpain activity (increased contents of p25 and spectrin breakdown products). Correlation analysis indicated the involvement of cdk5/p25 in MEK/ERK inhibition. These neurochemical effects of I2-alkylating BU99006 show a close relation between I1- and I2-IRs expressed in the mouse brain and between these receptors and the μ-OR, accompanied by cytoskeletal alterations and differential effects on multifunctional MAPK and cdk5 signalling pathways.
Laboratory of Neuropharmacology, IUNICS, University of the Balearic Islands (UIB), and IdISBa, Palma de Mallorca, Spain. Electronic address: b.keller@uib.es.
Benjamin
B
Keller
Laboratory of Neuropharmacology, IUNICS, University of the Balearic Islands (UIB), and IdISBa, Palma de Mallorca, Spain. Electronic address: jesus.garcia-sevilla@uib.es.
Jesús A
JA
García-Sevilla
D000478:Alkylation / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001572:Benzofurans / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D054755:Imidazoline Receptors / Q000096:biosynthesis*; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D011897:Random Allocation; D051381:Rats; D017450:Receptors, Opioid, mu / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
C468012:BU 99006; D001572:Benzofurans; D007093:Imidazoles; D054755:Imidazoline Receptors; D047908:Intracellular Signaling Peptides and Proteins; C503041:Nisch protein, mouse; D017450:Receptors, Opioid, mu; C487767:imidazoline receptor 2
BU99006; I(2)-imidazoline receptor alkylation; IR signalling; Nischarin; μ-Opioid receptor