Neurotrophins
Neurotrophins
Neurotrophins are responsible primarily for the regulation of cell proliferation, migration, and survival. They also have a hand in the modulation of axonal and dendritic outgrowth, and synapse formation. They have an abnormal expression patter in autistic patients.
BDNF, a neurotrophin, and its receptor, trkB, are expressed in cortical and hippocampal neurons and influences axonal and dendritic growth in a neuro specific and age-dependent manner. BDNF abnormalities have been implicated in schizophrenia and depression, brain disorders which show altered cortical maturation and plasticity. Some studies have found elevated levels of BDNF and NT4/5 in neonatal blood samples of ASD patients. One study found elevated levels of of BDNF along with auto-antibodies against BDNF. There is some evidence that BDNF regulation abnormalities could be a primary factor in autism development from a study on the gene CADPS2, which controls the exocytosis of BDNF-containing vesicles. It was found that CADPS2 was differently spliced in some autistic patients and that CADPS2 knockout mice have autistic-like phenotypes.1
BDNF trajectories may be altered in those with autism, which may explain why some studies find no difference in BDNF levels between control groups and ASD groups. Healthy individuals have an increase in serum BDNF concentration over the first several years, and then a slight decrease after adulthood is reached. ASD children up to nine years old had mean levels of serum BDNF that were significantly lower than teenagers, adults, or age-matched controls, which indicates a delayed BDNF increase during development.2
References
1. Pardo, CA et. al. The Neurobiology of Autism.Brain Pathol. 2007 Oct;17(4):434-47. PMID 17919129
2. Nickl-Jockschat T et. al. The role of neurotrophic factors in autism.Mol Psychiatry. 2010 Oct 12 PMID 20938434
