Key points are not available for this paper at this time.
Intrapleural injection of cholera toxin B fragment conjugated to saporin (CTB-SAP) selectively kills respiratory motor neurons, and mimics aspects of neurodegenerative diseases including breathing deficits. In this model, phrenic long-term facilitation (pLTF) induced by acute intermittent hypoxia is enhanced following 7 days (d) of CTB-SAP vs. control rats, whereas pLTF in 28d CTB-SAP treated rats is comparable to pLTF in controls suggesting that the underlying mechanisms of plasticity at both time points differ. Inflammation is a hallmark of neurodegenerative diseases and is known to prevent pLTF. Furthermore, ketoprofen (NSAID) delivery attenuates pLTF in 7d CTB-SAP-treated rats, but enhances it in 28d CTB-SAP-treated rats; this suggests that inflammation contributes to pLTF in 7d CTB-SAP-treated rats, but undermines pLTF in 28d CTB-SAP-treated rats. In addition, cervical spinal inflammatory marker gene expression ( e.g., TNF-a) is increased in CTB-SAP rats, and pilot data suggest that soluble TNF receptor 1 (sTNFR1) inhibition differentially affects pLTF (Nichols and Smith , ibid). Thus, the goal of the current study is to investigate TNFR1 as a pharmacological target that can modulate inflammation to maximize pLTF and breathing in CTB-SAP rats. We hypothesized that C4 TNFR1 expression would be increased on phrenic motor neurons and glial cells of CTB-SAP rats vs. controls. To address this, we studied TNFR1 expression on phrenic motor neurons and glial cells using immunohistochemistry, confocal microscopy, and ImageJ analysis in male Sprague Dawley rats 7 and 28 days after intrapleural injection of: CTB-SAP or un-conjugated CTB and SAP (control); n=8/group. Our preliminary data (n=4/group) suggest that phrenic TNFR1 expression is increased in 7d CTB-SAP rats vs. controls (p0.05). Further data analysis is underway for phrenic as well as glial TNFR1 expression in CTB-SAP rats vs. controls. If C4 TNFR1 expression is increased, this would suggest that TNFR1 is a viable target for therapeutic intervention in CTB-SAP rats, and potentially in patients with breathing deficits due to respiratory motor neuron death. NSF Computational Neuroscience grant, MU CVM COR grant, and Spinal Cord Injury & Disease Research Program grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Lewis et al. (Wed,) studied this question.