Abstract 389: Human Cardiac Sympathetic Nerves Switch the Neurotransmitter Property from Catecholaminergic to Cholinergic in Patients with Severe Heart Failure
[Background] Congestive heart failure (CHF) is characterized by activation of the sympathetic nervous system (SNS) with depletion of norepinephrine (NE) stores, which was initially considered to be the result of excess NE secretion and the loss of noradrenergic nerve terminals. Recent studies however have revealed that it is caused by down regulation of NE synthesis and re-uptake, although the molecular mechanism of down regulation of the sympathetic neuronal function remains unknown. We recently found in an animal model of CHF that the cardiac SNS switches the neurotransmitter property from catecholaminergic to cholinergic, mediated by cytokines LIF and CT-1 secreted from failing myocardium. This study was designed to investigate whether or not this cholinergic transdifferentiation of cardiac SNS occurs in patients with CHF.
[Methods & Results] (1) We analyzed 8 samples from patients who died of non-cardiac causes obtained at autopsy (control group), and 8 samples from patients with CHF (CHF group). Five of them died of CHF, and 3 were obtained from native hearts of transplant recipients. (2) The heart weight was significantly higher in the CHF group. (3) The gross morphology of the cardiac SNS did not differ between the two groups. HE and Masson trichrome staining showed disorganized cardiomyocytes and interstitial fibrosis in CHF. (4) Immunostaining for tyrosine hydroxylase (TH, sympathetic nerve marker) revealed that the epicardial nerve bundles and stellate ganglia of the control group had a predominance of TH+nerves, whereas those of CHF group were significantly decreased. (5) Immunostaining for choline transporter (CHT, cholinergic neuron marker) revealed that CHT+neurons were markedly increased in the epicardial nerve bundles of CHF hearts compared with the control group. Some nerves co-expressed both TH and CHT markers. (6) Immunostaining for choline acetyl transferase (ChAT, a cholinergic neuron marker) revealed that stellate ganglia had a lot of ChAT+neurons compared with the control. (7) Nissl staining showed that there was no difference between the two groups in neuron number in the stellate ganglia.
[Conclusions] These results indicated that in patients with CHF the cardiac sympathetic nerves also had cholinergic nerve properties.