Laminin and growth factor receptor activation stimulates differential growth responses in subpopulations of adult DRG neurons

Here they show laminin-induced neurite outgrowth and its relation to three known DRG neuronal types. They also show PI3K pathway is responsible. They also discuss this in the light of possible therapeutic targets. The study is limited in that that they only use invitrogen laminin (purified laminin-111) and isoform-specific effects cannot be seen, but they come to a number of highly interesting conclusions: 1) The current findings provide strong support for the use of the ECM molecule laminin in conjunction with NGF and GDNF in order to stimulate optimal levels of axon growth from all populations of regenerating sensory neurons. 2) identified intracellular signaling components that provide potential therapeutic targets when attempting to stimulate the regeneration of peripheral axons. Pharmacological alterations of the PI 3-K/Akt pathway resulting in activation of either PI 3-K or Akt could be beneficial. 3) Laminin-induced neurite growth occurs in the absence of added trophic factors only in heavy-chain neurofilament-positive and calcitonin gene-related peptide-positive DRG neurons [nerve growth factor (NGF)-responsive population]. In contrast, laminin alone is not sufficient to stimulate significant neurite growth from lectin Griffonia simplicifolia IB4-positive neurons (IB4+ve), although it is still required to elicit a growth response from these cells in the presence of glial-derived neurotrophic factor.