| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2847398 | Respiratory Physiology & Neurobiology | 2012 | 8 Pages |
Microglia and astrocytes play complex roles following spinal cord injury (SCI), contributing to inflammatory processes that both exacerbate injury and promote functional recovery by supporting neuro-protection and neuroplasticity. The crossed phrenic phenomenon (CPP) is an example of respiratory plasticity in which C2 cervical hemisection (C2HS) strengthens crossed-spinal synaptic pathways to phrenic motor neurons ipsilateral to injury. We hypothesized that microglia and astrocytes are activated in the phrenic motor nucleus caudal and ipsilateral to C2HS, suggesting their potential for involvement in the CPP. To test this hypothesis, an incomplete cervical spinal hemisection (C2 lateral injury; C2LI) was performed, and rats were allowed to recover for 1, 3, 14 or 28 days before collecting perfused spinal tissues. Microglia (via OX42) and astrocytes [via glial fibrillary acidic protein (GFAP)] were visualized with immunofluorescence microscopy in the C4–C5 ventral horn, the region encompassing most of the phrenic motor nucleus. OX42-occupied fractional area ipsilateral to injury increased with C2LI (vs. sham) at 1 (12.5 ± 1.8%, p < 0.001), 3 (29.0 ± 1.9%, p < 0.001), 14 (26.1 ± 3.1%, p < 0.001) and 28 (19.2 ± 2.0%, p < 0.001) days post-C2LI. GFAP-occupied fractional area also increased with C2LI at 3 (24.4 ± 3.2%, p < 0.001) and 14 (16.8 ± 8.3%, p = 0.012) days, but not at 1 (6.2 ± 3.9%, p = 0.262) or 28 (10.6 ± 3.9%, p = 0.059) days post-C2LI. Thus, microglia and astrocytes are activated in the phrenic motor nucleus caudal to C2LI, suggesting that they play a role in functional deficits and/or recovery following spinal injury.
► We examined microglia and astrocyte activation in the phrenic motor nucleus after C2 hemisection. ► Microglia activation was measured by OX42 immunofluorescence. ► Astrocytic activation was measured by GFAP immunofluorescence. ► Microglial activation increased at 1–28 days after injury. ► Astrocytic activation increased at 1–28 days after injury.
