Inhibition of calcium-stimulated adenylyl cyclase subtype 1 (AC1) for the treatment of pain and anxiety symptoms in Parkinson's disease mice model

Abstract

Pain and anxiety are two common and undertreated non-motor symptoms in Parkinson's disease (PD), which affect the life quality of PD patients, and the underlying mechanisms remain unclear. As an important subtype of adenylyl cyclases (ACs), adenylyl cyclase subtype 1 (AC1) is critical for the induction of cortical long-term potentiation (LTP) and injury induced synaptic potentiation in the cortical areas including anterior cingulate cortex (ACC) and insular cortex (IC). Genetic deletion of AC1 or pharmacological inhibition of AC1 improved chronic pain and anxiety in different animal models. In this study, we proved the motor deficit, pain and anxiety symptoms of PD in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice model. As a lead candidate AC1 inhibitor, oral administration (1 dose and seven doses) of NB001 (20 and 40 mg/kg) showed significant analgesic effect in MPTP-treated mice, and the anxiety behavior was also reduced (40 mg/kg). By using genetic knockout mice, we found that AC1 knockout mice showed reduced pain and anxiety symptoms after MPTP administration, but not AC8 knockout mice. In summary, genetic deletion of AC1 or pharmacological inhibition of AC1 improved pain and anxiety symptoms in PD model mice, but didn't affect motor function. These results suggest that NB001 is a potential drug for the treatment of pain and anxiety symptoms in PD patients by inhibiting AC1 target.

Keywords: Anxiety; NB001; Parkinson’s disease; adenylyl cyclase subtype 1; pain.

Figure 1.

Motor function, pain and anxiety symptoms assessment of MPTP-treated mice. (a) Motor performance of MPTP-treated and 6-OHDA-treated mice were significantly decreased compared with saline-treated mice in the Rotarod test. (b) A severe grip strength deficit was observed in MPTP-treated mice. (c–d) Mechanical threshold was reduced (c) and mechanical allodynia was increased (d) in MPTP-treated mice. (e) Representative traces showing the movement of mice in EPM (f–g) MPTP-treated mice exhibited increased anxiety-related behaviors in EPM (f) and there was no significant difference of entry number in EPM (g). *p < .05, **p < .01.

Figure 2.

Analgesic and anxiolytic effect of NB001 on MPTP-treated mice. (a) Compared with saline group, oral administration of 40 and 20 mg/kg NB001 (1 dose) increased mechanical threshold of MPTP-treated mice. (b) Oral administration of 40 and 20 mg/kg NB001 (7 dose) increased mechanical threshold of MPTP-treated mice. (c) Representative traces showing the movement of mice in EPM (d–e) After oral administration of 40 mg/kg NB001, MPTP-treated mice exhibited reduced anxiety-related behaviors in EPM (d) and there was no significant difference of entry number in EPM (e). *p < .05, **p < .01.

Figure 3.

No significant effect of NB001 on motor function. Compared to saline group, oral administration of 40 mg/kg NB001 didn’t affect the performance in grip strength test (a), RotaRod test (b), hanging time (c) and activity time (d) in homecage.

Figure 4.

Motor function, pain and anxiety symptoms assessment of MPTP-treated AC1 and AC8 knockout mice. (a–d) Compared to C57 mice, AC1 knockout mice showed decreased pain (a) and anxiety symptoms (c) after MPTP administration, but not AC8 knockout mice, (b) Representative traces showing the movement of mice in EPM, and there was no significant difference of entry number in EPM (d). (e–f) Compared to C57 mice, AC1 and AC8 knockout mice didn’t show significant difference in performance in grip strength test (e) and RotaRod test (f) *p < .05, **p < .01.

Figure 5.

A simplified model for the contribution of AC1 related synaptic plasticity in PD-related pain and anxiety. Synapses in the anterior cingulate cortex undergo long-term presynaptic and postsynaptic changes. At presynaptic sites, glutamate release is increased; at postsynaptic sites, the expression of AMPA receptors (AMPARs) is increased. In addition to postsynaptic increases in AMPAR expression, expression of postsynaptic NMDA receptors (NMDARs), Adenylyl cyclase 1 (AC1) is essential for the presynaptic enhancement of glutamate release and the postsynaptic potentiation of AMPARs and NMDARs. CaM, calmodulin; cAMP, cyclic AMP; FMRP, fragile X mental retardation protein (encoded by Fmr1); PKA, protein kinase A; PKMζ, protein kinase Mζ.