Serotonergic innervation of respiratory motor nuclei after cervical spinal injury: Impact of intermittent hypoxia

Ciesla, Marissa C.; Seven, Yasin B.; Allen, Latoya L.; Smith, Kristin; Zachary, A.; Simon, Alec K.; Holland, Ashley; Stefan, Kelsey; Ross, Ashley E.; Gonzalez‐Rothi, Elisa J.; Mitchell, Gordon S.

doi:10.1016/j.expneurol.2021.113609

Cited by 17 publications

(4 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As expected, we observed robust innervation of donor tissue from serotonergic host axons (5HT, Extended Data Fig 4e-h), which modulate respiratory networks 19,20 . We also observed bulbospinal axons from the ventral respiratory column (VRC), which have a lower propensity for spontaneous growth, innervating donor cells two months post-transplantation.…”

Section: [Results]supporting

confidence: 82%

Human spinal interneurons repair the injured spinal cord through synaptic integration

Zholudeva,

Fortino,

Agrawal

et al. 2024

Preprint

View full text Add to dashboard Cite

Advances in cell therapy offer promise for some of the most devastating neural injuries, including spinal cord injury (SCI). Endogenous VSX2-expressing spinal V2a interneurons have been implicated as a key component in plasticity and therapeutically driven recovery post-SCI. While transplantation of generic V2a neurons may have therapeutic value, generation of human spinal V2a neurons with rostro-caudal specificity and assessment of their functional synaptic integration with the injured spinal cord has been elusive. Here, we efficiently differentiated optogenetically engineered cervical V2a spinal interneurons (SpINs) from human induced pluripotent stem cells and tested their capacity to form functional synapses with injured diaphragm motor networks in a clinically-relevant sub-acute model of cervical contusion injury. Neuroanatomical tracing and immunohistochemistry demonstrated transplant integration and synaptic connectivity with injured host tissue. Optogenetic activation of transplanted human V2a SpINs revealed functional synaptic connectivity to injured host circuits, culminating in improved diaphragm activity assessed by electromyography. Furthermore, optogenetic activation of host supraspinal pathways revealed functional innervation of transplanted cells by host neurons, which also led to enhanced diaphragm contraction indicative of a functional neuronal relay. Single cell analyses pre- and post-transplantation suggested the in vivo environment resulted in maturation of cervical SpINs that mediate the formation of neuronal relays, as well as differentiation of glial progenitors involved in repair of the damaged spinal cord. This study rigorously demonstrates feasibility of generating human cervical spinal V2a interneurons that develop functional host-transplant and transplant-host connectivity resulting in improved muscle activity post-SCI.

show abstract

Section: [Results]supporting

confidence: 82%

Human spinal interneurons repair the injured spinal cord through synaptic integration

Zholudeva,

Fortino,

Agrawal

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Differences between mRNA (this study) versus protein levels could explain this apparent discrepancy. In studies using other, repetitive AIH protocols (10 (Satriotomo et al, 2012) or 4 weeks of AIH 3x per week (MacFarlane et al, 2018); or 28 days of dAIH (Ciesla et al, 2021), serotonergic innervation within the phrenic motor nucleus is minimally affected. However, our results support observations reported by MacFarlane et al (MacFarlane et al, 2018), who found no changes in Bdnf, Htr2b or Htr7 mRNA in ventral cervical homogenates following 4 weeks of repetitive AIH (3x per week) in male rats (MacFarlane et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Daily Acute Intermittent Hypoxia Elicits Age & Sex-Dependent Changes in Molecules Regulating Phrenic Motor Plasticity

Nair,

Marciante,

Lurk

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

Acute intermittent hypoxia (AIH) elicits a form of respiratory motor plasticity known as phrenic long-term facilitation (LTF). Repetitive daily AIH (dAIH) exposure enhances phrenic LTF, demonstrating a form of metaplasticity. Two additional factors impacting phrenic LTF are age and sex. For example, moderate AIH-induced phrenic LTF decreases with age in males, but increases in middle-aged females. However, little is known concerning cellular mechanisms of dAIH effects or age-dependent sexual dimorphism in phrenic LTF. Moderate AIH elicits distinct signaling cascades within phrenic motor neurons initiated by 5HT2 receptors (Q pathway) versus adenosine 2A or 5HT7 receptors (S pathway), respectively. The Q and S pathways interact via mutual crosstalk inhibition, a powerful regulator of phrenic LTF. To test the hypothesis that dAIH, age and sex effects on phrenic LTF are associated with differential expression of molecules known to regulate the Q and S pathways, we assessed mRNA of key regulatory molecules in ventral cervical homogenates from spinal segments containing the phrenic motor nucleus from young (3 month) and middle-aged (12 month) male and female Sprague-Dawley rats. Since CNS estrogen levels impact molecules regulating the Q and/or S pathways, mRNA was correlated with serum estradiol. Rats (n=8/group) were exposed to sham (21% O2) or dAIH (15, 1 min episodes of 10.5% inspired O2 per day) for 14 days, and sacrificed 24 hours post-dAIH. mRNA for molecules known to regulate phrenic LTF were assessed via RT PCR, including: brain derived neurotrophic factor (Bdnf); serotonin 2A (Htr2a); 2B (Htr2b); and (Htr7) receptors; adenosine 2a (Adora2a) receptors; exchange protein activated by cAMP (Epac1); p38 MAP kinase [Mapk14 (α) & Mapk11 (β)]; PKA catalytic subunit (Prkaa1); PKA regulatory subunit (Prkar1a); fractalkine (Cx3cl1); phosphodiesterase type 4 (Pde4b); NAPDH-gp91 (Cybb) and p47 (ncf1); and the PKCδ isoform (Prkcd). Significantly higher Pde4b, Adora2a, and Prkcd mRNA were found in young and middle-aged females versus age-matched males; Epac1 was elevated, but only in young females (p<0.001). Ncf1 was increased in middle-aged versus young adult rats of both sexes (p<0.01). Ncf1, Cx3cl1, Adora2a and Prkcd mRNA were reduced by dAIH in middle-aged females (p<0.01), but not other groups. Serum estradiol levels positively correlated with Epac1 (r2=0.29, p=0.002), Mapk14 (r2=0.31, p=0.001), Mapk11 (r2=0.20, p=0.014), and Prkar1a (r2=0.20 p=0.013) mRNA. With higher serum estradiol levels, dAIH decreased Mapk14 mRNA (slope difference p=0.001). Thus, age, sex and dAIH preconditioning influence molecules known to regulate the Q and S pathways to phrenic motor facilitation. These novel findings advance our understanding of phrenic LTF, and inform translational research concerning the therapeutic potential of dAIH to treat breathing deficits in individuals of different ages or sex.

show abstract

“…In the present study, cervical spinal cord hemisection was performed at level C2. Spinal hemisection at the second cervical spinal cord (i.e., C2Hx) is widely used to investigate respiratory function following cervical SCI in rodent models [13] ; [14]; [15] ; [16] .…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Diaphragmatic electromyography of cervical spinal cord hemi section in Rat model

Fouad

Rezk

Rizk

et al. 2022

Mansoura Veterinary Medical Journal

View full text Add to dashboard Cite

Estimation the degree of induced hemisection damage of the cervical segments of the two separately diaphragmatic pillars in rat model using Electromyography (EMG). Design: Prospective controlled study. Animals: Sixteen Sprague dawely rats were divided into 2 groups Procedures: Cervical hemi lateral cord section below the cervical dorsal root number 2 was induced with micro scalpel. After 28 days post-injury, EMG record was done at the two diaphragmatic crural regions, followed by histopathological and immunohistochemical examinations. Results: There was significant decrease in mean integrated EMG activity of LT diaphragmatic muscles than RT one in the hemi sectioned group P<0.05. Moreover, there was a significant decrease (P<0.05) in the integrated traces (mv) for peak burst area of LT diaphragmatic muscles activity. On histopathological examination, affected neurons of hemi-sectioned group appeared shrunken with chromatolysis, others were completely lost and replaced by cavities. The neutrophil adjacent to the necrotic neurons lost its homogeneous appearance and appeared vacuolated or edematous with significant decrease in the number of viable motor neurons compared to the control group (P < 0.05). On other hand, the astrocytosis become more evident and the number of astrocytes was significantly increased (P < 0.05). The surrounding white matter exhibited severs degeneration and demyelination. Glial fibrillary acidic protein (GFAP) immune expression for hemi-sectioned group was significantly increased than control group (P < 0.05) Conclusion and clinical relevance: Parallel impairment of the diaphragmatic EMG occurred to the decrease in the number of viable motor neurons of the anterior horn of the cervical segment below the level of the cervical hemisection together with the disintegration of Nissl bodies and the developed astrocytosis.

show abstract

Serotonergic innervation of respiratory motor nuclei after cervical spinal injury: Impact of intermittent hypoxia

Cited by 17 publications

References 54 publications

Human spinal interneurons repair the injured spinal cord through synaptic integration

Human spinal interneurons repair the injured spinal cord through synaptic integration

Daily Acute Intermittent Hypoxia Elicits Age & Sex-Dependent Changes in Molecules Regulating Phrenic Motor Plasticity

Evaluation of Diaphragmatic electromyography of cervical spinal cord hemi section in Rat model

Contact Info

Product

Resources

About