Optical Control of Cardiac Function with a Photoswitchable Muscarinic Agonist

Abstract

Light-triggered reversible modulation of physiological functions offers the promise of enabling on-demand spatiotemporally controlled therapeutic interventions. Optogenetics has been successfully implemented in the heart, but significant barriers to its use in the clinic remain, such as the need for genetic transfection. Herein, we present a method to modulate cardiac function with light through a photoswitchable compound and without genetic manipulation. The molecule, named PAI, was designed by introduction of a photoswitch into the molecular structure of an M2 mAChR agonist. In vitro assays revealed that PAI enables light-dependent activation of M2 mAChRs. To validate the method, we show that PAI photoisomers display different cardiac effects in a mammalian animal model, and demonstrate reversible, real-time photocontrol of cardiac function in translucent wildtype tadpoles. PAI can also effectively activate M2 receptors using two-photon excitation with near-infrared light, which overcomes the scattering and low penetration of short-wavelength illumination, and offers new opportunities for intravital imaging and control of cardiac function.

Control of brain state transitions with light

“…We took advantage of the thermal stability of both PAI forms to apply initially the inactive one (cis-PAI) at 200 nM in cortical slices (n = 15), in the absence of white light to avoid photoconversion to trans-PAI during the recordings. 23 As shown in Fig.2, 200 nM cis-PAI evoked minor changes in OF (from 0.53 ± 0.04 Hz in control conditions to 1.04 ± 0.14 Hz with cis-PAI), and no significant effects in the relative firing rate of the Up-states (from 0.98 ± 0.09 a.u. in the control to 0.86 ± 0.10 a.u.…”

“…The oscillatory frequency of the network was greatly increased already at 100 nM Iperoxo, and lead to periods of seizure-like discharges, in agreement with previous studies performed by knockout mice and pilocarpine 39,40 in which pathologic activation of muscarinic acetylcholine receptors induced seizures. Photocontrol of muscarinic signaling was subsequently achieved in vitro and in vivo with the photochromic iperoxo derivative PAI, 23 which is targeted allosterically at M2 subtype receptors ( Fig. 2-4).…”

“…11 In order to remotely control these states, we aimed at the observed muscarinic neuromodulation using PAI, a photoswitchable Iperoxo derivative that allows reversibly activating M2 mAChRs with light. 23 M2 receptors play relevant roles in several CNS disorders, 22 and regulating their activity and subsequent effects on cortical neuronal networks may provide new therapeutic opportunities for these cholinergic diseases.…”

“…In comparison, cis-PAI displayed significantly weaker effects, in agreement with the reported PAI properties. 23 At 100 nM and 300 nM, cis-PAI did not alter the spontaneous activity observed in control experiments (control OF: 0.48 ± 0.037 Hz; 100 nM cis-PAI OF: 0.52 ± 0.07 Hz; 300 nM cis-PAI OF: 0.87 ± 0.2 Hz), in contrast to the strong alterations in oscillatory activity obtained with 100 nM and 300 nM trans-PAI (Fig. 2).…”

“…Since the cholinergic system is key to modulate various CNS functions, 22 the use of selective and photoswitchable cholinergic drugs to spatiotemporally control cortical activity would have relevant scientific and clinical implications. Herein, we report that the cholinergicdependent brain state transitions in the neocortex can be directly controlled using Phthalimide-Azo-Iper (PAI) 23 a photoswitchable agonist that targets M2 muscarinic acetylcholine receptors (mAChRs) without requiring electric or genetic manipulation. In particular, PAI enables modulating spontaneous emerging slow oscillations (SO) in neuronal circuits.…”