Plasticity occurs in a specific phenotype of neurons in the nucleus tractus solitarius of dystrophin gene‐mutated rats

Abstract

Duchenne muscular dystrophy (DMD) is a severe progressive neuromuscular disorder that causes cardiac and respiratory failure. Patients with DMD have tachycardia and autonomic nervous dysfunction at a young age, which can potentially worsen cardiorespiratory function. Therefore, we hypothesised that plasticity occurs in neurons of the cardiorespiratory brainstem nucleus (nucleus tractus solitarius [NTS]) due to DMD, thus affecting neuronal regulation because afferent information from cardiorespiratory organs changes with disease progression. Patch‐clamp experiments were performed on second‐order NTS neurons from Dmd‐mutated (Dm) rats that showed no functional dystrophin protein expression, as confirmed by immunohistochemistry. NTS neurons are classified into two electrophysiological phenotypes: one showing a delayed onset of spiking from hyperpolarised membrane potentials, namely, delayed‐onset spiking (DS)‐type neurons, and the other showing a rapid onset, namely, rapid‐onset spiking‐type neurons. Neuroplasticity mainly occurs in DS‐type neurons in Dm rats and is characterised by blunted neuronal excitability accompanied by reduced outward currents and a facilitatory effect on synaptic transmission, that is, an increased frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs) without changes in the amplitude and an increased amplitude of tractus solitarius‐evoked EPSCs without changes in the paired‐pulse ratio. Although we cannot rule out the possibility that the neuroplastic changes observed in Dm rats were caused by dystrophin deficiency in the neurons themselves, the plasticity could be caused by cardiorespiratory deterioration and/or adaptation in DMD patients.

Adverse events associated with eteplirsen: A disproportionality analysis using the 2016–2023 FAERS data

“…A prospective study reported an adolescent developing cardiomyopathy while on eteplirsen, consistent with DMD's typical progression [ 27 ]. It has also been shown that DMD is associated with an increased likelihood of cardiac events [ 28 ]and can precipitate respiratory failure [ 29 ]. Whether the causative factors behind these complications are inherent to the disease itself or are triggered or exacerbated by the medication deserves further investigation We call for vigilance in these adverse effects of concern so that appropriate preventive measures can be taken.…”