Dynamic changes in dopamine neuron function after DNSP-11 treatment: Effects in vivo and increased ERK 1/2 phosphorylation in vitro

• A peptide (DNSP-11), derived from the proregion of GDNF, was investigated.
• DNSP-11 was delivered to the substantia nigra to investigate in vivo effects.
• DNSP-11 caused increased dopamine release in the dorsal, but not ventral, striatum.
• The release effects occurred 2 weeks after treatment but not at 1- or 4-weeks.
• DNSP-11 increased ERK1/2 phosphorylation in neuronal cells.

Glial cell-line derived neurotrophic factor (GDNF) has demonstrated robust effects on dopamine (DA) neuron function and survival. A post-translational processing model of the human GDNF proprotein theorizes the formation of smaller, amidated peptide(s) from the proregion that exhibit neurobiological function, including an 11-amino-acid peptide named dopamine neuron stimulating peptide-11 (DNSP-11). A single treatment of DNSP-11 was delivered to the substantia nigra in the rat to investigate effects on DA-neuron function. Four weeks after treatment, potassium (K+) and d-amphetamine evoked DA release were studied in the striatum using microdialysis. There were no significant changes in DA-release after DNSP-11 treatment determined by microdialysis. Dopamine release was further examined in discrete regions of the striatum using high-speed chronoamperometry at 1-, 2-, and 4-weeks after DNSP-11 treatment. Two weeks after DNSP-11 treatment, potassium-evoked DA release was increased in specific subregions of the striatum. However, spontaneous locomotor activity was unchanged by DNSP-11 treatment. In addition, we show that a single treatment of DNSP-11 in the MN9D dopaminergic neuronal cell line results in phosphorylation of ERK1/2, which suggests a novel cellular mechanism responsible for increases in DA function.