[The effect of central administration of the neurotrophic factors BDNF and GDNF on the functional activity and expression of the serotonin 5-HT2A receptors in mice genetically predisposed to depressive-like behavior]

Brain serotonin (5-HT) system plays an important role in the control of normal and pathological behavior. 5-HT2A receptors are widely implicated in the regulation both normal functions and psychopathologies, especially schizophrenia and depression. Here, we investigated implication of 5-HT2A receptor in mechanisms of neurotrophic factors BDNF and GDNF action. We found that the acute intracerebroventricular injection of BDNF produced considerable increase in 5-HT2A receptor functional activity in ASC mice. Moreover, BDNF injection led to the increasing of 5-HT2A receptor gene expression in the hippocampus and its decrease in the frontal cortex without any effects in the midbrain. On the contrary, GDNF injection failed to alter 5-HT2A receptor functional activity, but increased the 5-HT2A receptor gene expression in the frontal cortex without any effects in the hippocampus and midbrain. Thus, an effect of the central administration of the neurotrophic factors BDNF and GDNF on the 5-HT2A receptor functional activity and gene expression was shown. The results indicate the implication of 5-HT2A receptor in the mechanisms of BDNF and GDNF action.

Effect of glial cell line-derived neurotrophic factor on behavior and key members of the brain serotonin system in mouse strains genetically predisposed to behavioral disorders

The effect of glial cell line-derived neurotrophic factor (GDNF) on behavior and on the serotonin (5-HT) system of a mouse strain predisposed to depressive-like behavior, ASC/Icg (Antidepressant Sensitive Cataleptics), in comparison with the parental "nondepressive" CBA/Lac mice was studied. Within 7 days after acute administration, GDNF (800 ng, i.c.v.) decreased cataleptic immobility but increased depressive-like behavioral traits in both investigated mouse strains and produced anxiolytic effects in ASC mice. The expression of the gene encoding the key enzyme for 5-HT biosynthesis in the brain, tryptophan hydroxylase-2 (Tph-2), and 5-HT1A receptor gene in the midbrain as well as 5-HT2A receptor gene in the frontal cortex were increased in GDNF-treated ASC mice. At the same time, GDNF decreased 5-HT1A and 5-HT2A receptor gene expression in the hippocampus of ASC mice. GDNF failed to change Tph2, 5-HT1A , or 5-HT2A receptor mRNA levels in CBA mice as well as 5-HT transporter gene expression and 5-HT1A and 5-HT2A receptor functional activity in both investigated mouse strains. The results show 1) a GDNF-induced increase in the expression of key genes of the brain 5-HT system, Tph2, 5-HT1A , and 5-HT2A receptors, and 2) significant genotype-dependent differences in the 5-HT system response to GDNF treatment. The data suggest that genetically defined cross-talk between neurotrophic factors and the brain 5-HT system underlies the variability in behavioral response to GDNF.