Abstract
BackgroundMinocycline, a second-generation tetracycline antibiotic, exhibits anti-inflammatory and neuroprotective effects in various experimental models of neurological diseases, such as stroke, Alzheimer’s disease, amyotrophic lateral sclerosis and spinal cord injury. However, conflicting results have prompted a debate regarding the beneficial effects of minocycline.MethodsIn this study, we analyzed minocycline treatment in organotypic spinal cord cultures of neonatal rats as a model of motor neuron survival and regeneration after injury. Minocycline was administered in 2 different concentrations (10 and 100 µM) at various time points in culture and fixed after 1 week.ResultsProlonged minocycline administration decreased the survival of motor neurons in the organotypic cultures. This effect was strongly enhanced with higher concentrations of minocycline. High concentrations of minocycline reduced the number of DAPI-positive cell nuclei in organotypic cultures and simultaneously inhibited microglial activation. Astrocytes, which covered the surface of the control organotypic cultures, revealed a peripheral distribution after early minocycline treatment. Thus, we further analyzed the effects of 100 µM minocycline on the viability and migration ability of dispersed primary glial cell cultures. We found that minocycline reduced cell viability, delayed wound closure in a scratch migration assay and increased connexin 43 protein levels in these cultures.ConclusionsThe administration of high doses of minocycline was deleterious for motor neuron survival. In addition, it inhibited microglial activation and impaired glial viability and migration. These data suggest that especially high doses of minocycline might have undesired affects in treatment of spinal cord injury. Further experiments are required to determine the conditions for the safe clinical administration of minocycline in spinal cord injured patients.
Highlights
The repair and regeneration of motor neurons in the injured spinal cord is clinically relevant
We compared the number of surviving motor neurons and the percentage stained area of anti-pan neuronal neurofilament (pan-NF), anti-ionized calcium binding adaptor molecule 1 (IBA-1), anti-glial fibrillary acid protein (GFAP) and DAPI between the control cultures receiving no minocycline and minocyclinetreated cultures (+Minocycline supplement (Mino))
Fluorescence intensities were measured for astroglial and microglial stainings
Summary
The repair and regeneration of motor neurons in the injured spinal cord is clinically relevant. Several strategies have been used to enhance axonal regeneration and functional recovery after spinal cord injury, including the reduction of inflammation, inhibiting the formation of a glial scar, degradation/blockade of inhibitory molecules to the delivery of growth factors and transplantation of cells [12,13,14]. Results: Prolonged minocycline administration decreased the survival of motor neurons in the organotypic cultures This effect was strongly enhanced with higher concentrations of minocycline. Conclusions: The administration of high doses of minocycline was deleterious for motor neuron survival It inhibited microglial activation and impaired glial viability and migration. These data suggest that especially high doses of minocycline might have undesired affects in treatment of spinal cord injury. Further experiments are required to determine the conditions for the safe clinical administration of minocycline in spinal cord injured patients
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call