Filamentous microtubules in the neuronal spinous process and the role of microtubule regulatory drugs in neuropathic pain.

Structural and regulatory components in the spinous processes neurons are still not fully understood. While the presence, regulation and function of actin cytoskeleton are now well established, involvement of microtubule cytoskeleton is only now being studied. In spite of biochemical, genetic and anatomical evidence, neurobiologists have experienced difficulties to even establish the physical presence and to demonstrate the functional relevance of "filamentous microtubules" in the spines. However, recent studies have demonstrated that filamentous microtubules regularly invade most spines. Moreover, functional aspects like stabilization and maturation of spines can be directly correlated with the presence of these microtubules; low doses of microtubule stabilizers can induce as many as 50% more spines. Clinically, knowledge of microtubule active drugs is extremely important, especially in the area of oncology, where they are commonly used as anti-neoplastic agents. Unfortunately, a major dose-limiting side effect of this class of drugs is a painful peripheral neuropathy. We review the recent concept of microtubules in the spine, and also critically analyze their role in chemotherapy-induced neuropathic pain.