Fig. 3.

Ratio of D1 to D3 receptor expression with age in striatum and lumbar spinal cord. In the striatum, D1-to-D3 ratio increases gradually with age (solid line) but is only significantly increased at 2 yr of age over 2-mo-old controls (asterisk). In contrast, in the lumbar spinal cord, D1-to-D3 ratios grow faster (dashed line) and are significantly increased over 2-mo-old animals at both 1 yr and 2 yr of age (octothorpes).