- Ghrelin modulates the activity and synaptic input organization of midbrain dopamine neurons while promoting appetite. Abizaid, A., Liu, Z.W., Andrews, Z.B., Shanabrough, M., Borok, E., Elsworth, J.D., Roth, R.H., Sleeman, M.W., Picciotto, M.R., Tschöp, M.H., Gao, X.B., Horvath, T.L. J. Clin. Invest. (2006)