I guess it is known that microtubules are directly involved in the direction of neurotransmitters through physiological synapses. What is still under potential debate is to what extent they are utilised as effectors for neurotransmitter signalling. You may find the link useful.

http://www.ncbi.nlm.nih.gov/pubmed/20687109

I'm not sure if I'm understanding your question correctly, but this article may be of interest: 

Gardiner, J., Overall, R., & Marc, J. (2011). The microtubule cytoskeleton acts as a key downstream effector of neurotransmitter signaling. Synapse, 65(3), 249-256.

Another interesting article: 

Tien, N. W., Wu, G. H., Hsu, C. C., Chang, C. Y., & Wagner, O. I. (2011). Tau/PTL-1 associates with kinesin-3 KIF1A/UNC-104 and affects the motor's motility characteristics in C. elegans neurons. Neurobiology of disease, 43(2), 495-506.

Dear Abolfazi,

Indeed microtubules are important in function of ion channels and neurotransmission. I think most importantly the microtubules are involved in transport of proteins (including ion channels), neurotransmitters/modulators, organelles (including mitochondria) from soma to the periphery. This microtubular role is very critical for axonal transport of neurotransmitters to the pre-synaptic terminal, without it the terminal will not have enough neurotransmitter and energy required for synaptic transmission. Anything that disturbs or reduces microtubular function results in significant neuronal dysfunction.

best wishes,

Refik

Dear Abolfazi, both tubulin and microtubules can alter the gene expression of proteins that are of the highest importance for the functioning of some cell type. It has been shown long time ago in lactocytes, the specific cell type of the mammary gland . Here are two examples considering the casein(s) gene(s) expression (try to find analogous findings considering brain or neuron functioning if there is any) :

(1) Reprod Nutr Dev. 1990;30(3):431-8.

The possible involvement of tubulin in transduction of the prolactin signal.

Houdebine LM1.

Author information

1INRA, Unité de Différenciation Cellulaire, Jouy-en-Josas, France.

Abstract

Prolactin has many different biological functions. It stimulates Nb2 cell multiplication through the kinase C transduction mechanism, casein secretion through the phospholipase A2-arachidonic acid-leukotrienes cascade and milk protein gene expression through an unknown mechanism. Colchicine and other tubulin binding drugs inhibit casein gene expression and DNA synthesis stimulated by prolactin whereas chemical compound which alter microtubule without binding tubulin exert no inhibitory effect. Myo-inositol which suppresses some of the colchicine actions in several biological systems does not restore prolactin action after an inhibition by the drug. These data suggest that a tubulin molecule in the vicinity of the prolactin receptor, rather than actual microtubules, is involved in the transduction of the prolactin message from its receptor to milk protein genes.

PMID: 2397036 [PubMed - indexed for MEDLINE]

(2) Mol Cell Endocrinol. 1980 Jan;17(1):1-15.

Effects of lysomotropic agents, and of microfilament- and microtubule-disrupting drugs on the activation of casein-gene expression by prolactin in the mammary gland.

Houdebine LM, Djiane J.

Abstract

The organ-culture technique was used to investigate the effects of lysomotropic agents (NH4Cl and chloroquine) and of modifiers of microfilaments (cytochalasin B) and microtubules (colchicine) on the induction of casein synthesis and the accumulation of casein mRNA by prolactin in the rabbit mammary gland. Neither chloroquine nor NH4Cl altered the lactogenic action of prolactin. Cytochalasin B attenuated the response to prolactin in terms of casein synthesis. However, this drug did not hamper the accumulation of casein mRNA. Colchicine exhibited a marked specific inhibitory effect on the induction of casein synthesis. It also prevented the accumulation of casein mRNA. These results suggest that a putative degradation of the internalized prolactin--receptor complex by lysosomes is not strictly involved in prolactin action. In addition, the integrity of the microfilaments seems unnecessary in the process of casein-gene activation by prolactin. By contrast, the integrity of the microtubule network seems absolutely necessary to ensure the transmission of prolactin information to the nucleus.

PMID: 6244204 [PubMed - indexed for MEDLINE]

Good luck!