Axon regeneration is one of the many challenges confronting spinal cord researchers. The axon is a critical communication path from the nerve cell, with many sensory axons extending from the spine to the brain. When the spine is severely damaged that connection is lost, and gaps form in the healed spine that fill with fluid, an environment that complicates regeneration efforts since axons can’t grow across the lesion cavity. Therefore, to be successful, regeneration therapy must stimulate growth and provide a scaffold that creates an appropriate environment to support axonal growth.
The most dramatic axonal growth seen in the UCSD study was in rats pre-treated with cyclic AMP (cAMP). The team injected cAMP, an important cellular messenger that regulates various metabolic processes, directly into the nerve cell nucleus before creating the lesions. After surgical severance of the spine, the injury site was implanted with a tissue bridge of bone marrow stromal cells and treated with neurotrophins (growth factor). In these rats, over a three-month period significant growth of axons was noted, extending into and beyond the tissue graft. Pre-treatment with cAMP could be a practical approach for treating patients with established, chronic spinal cord injuries, a possibility that is the subject of current study by the UCSD group.
Co-authors of the paper are Paul Lu, Ph.D., UCSD Department of Neurosciences; Leonard Jones Ph.D., UCSD Department of Neurosciences and Veterans Affairs Medical Center, San Diego; and Marie T. Filbin, Ph.D., Biology Department, Hunter College, New York.
The research was supported by the National Institutes of Health, the Veterans Administration, the Canadian Spinal Research Organization, and the Swiss Institute for Research into Paraplegia.
A severed axon degenerates on the side away from the cell body. Somehow it needs to find its way to make the right synapse. This may work better for sensory neurons as you can access the cell body in the ganglion near the spinal cord, whereas motor neurons may be up in the brain.
The first problem is merely to get the axons to grow in a non-permissive environment. Not only do they need a substrate, and won’t grow across fluid, but they also are surrounded by signalling molecules that inhibit growth cones (the growing bit at the end of the axon).
Most of the regeneration work so far has of necessity concentrated on the first problem. One thought is that once new connections are made, plasticity in the cortex will allow the brain to use whatever connections are there.
This article is full of inaccuracies, by the way. It pretty much dupes the press release and adds in misinformation.
For example, the author states that cAMP was injected into the nuclei of the neurons. Not true. It was injected into the dorsal root ganglia, where the cell bodies of the neurons in question lie.
The real cool thing about this particular publication is that they used a combination of factors to promote axonal outgrowth. It was the use of both cAMP and a peptide growth factor called neurotrophin-3 (NT-3) to promote axon growth into the lesion. Neither factor worked well alone.
Here’s the abstract of the article, Combinatorial Therapy with Neurotrophins and cAMP Promotes Axonal Regeneration beyond Sites of Spinal Cord Injury.
Hey! I resemble that comment! I only added the first two sentences and for the rest copied the press release verbatim. If I dupe what I’m told, where did I add in misinformation? Regardless, corrections are always welcome and I thank you for pointing them out.
I apologize for mistaking your article as being written by you. I started to read the press release after your article, realized it was verbatim and stopped reading. If I had done, I’d have seen that the error was due to the PR person misunderstanding rather than you.
That said, if you copy something verbatim, it might behoove you to tell your reader and give credit to the source. I realize that press releases are meant to be used as such, but in science circles your choice wouldn’t be looked upon favorably.
Especially when it copies an error.
Just before this article went into verbatim mode, immediately after after my paltry two original lead-n sentences, were the words-and-link “From a UCSD press release”. I consider this adequate attribution that “tells your reader and give credit to the source” as you correctly note is appropriate. If you will notice, I follow this exact convention (saying “from an XYZ press release” that is linked to the press release being quoted verbatim) in EVERY SINGLE ONE of my articles based on press releases. The only thing I add is three-to six relevant links on various keywords already in the press release. If anybody considers this some kind of con job or intellectual theft, please speak up. I think it’s fine, and I’m so busy this style of article has unfortunately become the backbone of this site. I’d love to write two long original articles every single day, but I Just Don’t Have Time.
I really want to know how the electrical signals in the third ventricle between the lobes of the thalamus look like. Is there any study on this?