Figure 7: i.c.v injection of ghrelin increases dopamine release and turnover rate in the striatum.
From: Peptide hormone ghrelin enhances neuronal excitability by inhibition of Kv7/KCNQ channels
(a–d) Contents of dopamine and its metabolites in rat striatum were measured using HPLC. (a) Striatal dopamine levels of groups before and after i.c.v. injections of ghrelin (10–1,000 nM, in 5 μl). n=6. Each bar represents the mean±s.e.m. (b) Striatal DOPAC levels were increased after treatment with 100 and 1,000 nM ghrelin (n=6. Each bar represents the mean±s.e.m. *P<0.05, Ghrelin versus Control). (c) Striatal HVA levels were increased after treatment with 100 and 1,000 nM ghrelin (n=6. Each bar represents the mean±s.e.m. *P<0.05, Ghrelin versus Control). (d) i.c.v. injection of ghrelin (100 and 1,000 nM) increased the dopamine turnover rate (n=6. Each bar represents the mean±s.e.m. *P<0.05, Ghrelin versus Control). (e) Dopamine release in vivo evoked by stimulation of the medial forebrain bundles was recorded with carbon fibre electrodes in the striatum using fast cyclic voltammetry. Ghrelin (i.c.v. 1,000 nM, 5 μl) significantly increased the dopamine release from 1.3 ±0.2 μM to 3.9±0.5 μM (n=6. Each bar represents the mean±s.e.m. **P<0.01, Ghrelin versus Control).
