Description
BQCA is a highly selective positive allosteric modulator of the M
1 muscarinic acetylcholine receptor (mAChR), as it dose-
dependently reduces the concentration of acetylcholine required to activate the M
1 receptor. The effective range for potentiation of M
1 in cells by BQCA is 0.1 to 100 μM with an inflection point value of 845 nM when 3 nM acetylcholine is used. BQCA displays no potentiation, agonism, or antagonism at other mAChRs at concentrations up to 100 μM. It has excellent brain penetration and increases the firing rate of medial prefrontal cortex neurons
in vivo in rats. BQCA prevents scopolamine-
induced memory deficits in both contextual fear conditioning and a spontaneous alternation task in mice. It also restores impairment in reversal learning in a mouse model of Alzheimer’s disease and improves memory performance in rats.
Uses
BQCA is a highly selective positive allosteric modulator of the M1 muscarinic acetylcholine receptor (mAChR).
Biochem/physiol Actions
BQCA is a potent muscarinic M1 receptor positive allosteric modulator with selectivity for M1 over M2-M5. It potentiates M1 activity in in vitro and in vivo assays and is orally bioavailable. Muscarinic 1 (M1) receptors are expressed in brain regions responsible for attention and memory, including hippocampus, cortex, and striatum. BQCA binds allosterically to M1 to enhance the binding and efficacy of ACh at the receptor. M1 activation is a proposed mechanism for increasing information processing in disease states, such as Alzheimer′s. M1 agonists are being studied as potential therapeutic agents to treat Alzheimer′s disease and the cognitive and negative symptoms of schizophrenia. BQCA has been shown to improve performance in cognition tasks and increase cerebral blood flow.
in vitro
bqca alone showed no effect on calcium mobilization up to 10 μm but increased ach potency 128.8 ± 20.1-fold at 100 μm. in cho cells stably expressing human m1, bqca (100 μm) activated m1 in the absence of ach to an approximate 50% maximal response. bqca had no effect on m2–m5, indicating 100-fold selectivity [1]. bqca dose-dependently reduced the concentration of acetylcholine required to activate the m1 receptor [1]. the effective range for potentiation of m1 in cells by bqca was 0.1 to 100 μm, with an inflection point value of 845 nm when 3 nm acetylcholine was used [1].
in vivo
in wild-type mice, bqca (15 mg/kg) induced c-fos and arc rna in the cortex, hippocampus, and cerebellum and the arc was also elevated in the striatum. bqca had no effect in m1-/- mice. in wild-type mice, oral administration of 15 mg/kg bqca increased the ratio of phosphoerk (perk) to total erk by 28%. bqca showed excellent brain penetration and increased the firing rate of medial prefrontal cortex neurons in vivo in rats [2].
References
[1] ma l, seager m a, wittmann m, et al. selective activation of the m1 muscarinic acetylcholine receptor achieved by allosteric potentiation[j]. proceedings of the national academy of sciences, 2009, 106(37): 15950-15955.
[2] shirey j k, brady a e, jones p j, et al. a selective allosteric potentiator of the m1 muscarinic acetylcholine receptor increases activity of medial prefrontal cortical neurons and restores impairments in reversal learning[j]. journal of neuroscience, 2009, 29(45): 14271-14286.
