The GHR -/- mouse has proven to be a useful and unique model to study the role of GH on growth, development, and function of the CNS. GHR-/- mice show a relative increase in the size of the brain and pituitary with concomitant changes in the morphology of these tissues. The disruption of GH signaling alters the feedback mechanisms that control GH expression. This results in changes in expression of several hypothalamic proteins that influence GH expression and also results in structural changes in the pituitary. Several measures of motorneuron development were unaltered in the GHR-/- mouse, indicating this is a GH-independent process. An examination of the brain of GHR-/- animals shows increased neuron cell density and hypoplasia of glial cells compared to controls. The single investigation of cognition in these animals has shown protection from age-related decline in memory in the GHR-/- mice. There is a great opportunity to use these mice to facilitate further research into the role GH plays in neural development and function.