Neurotrophic factor for serotonergic neurons prevents degeneration of grafted raphe neurons in the cerebellum.

³H]SCH 23390 binds stereospecifically and with high affinity to D₁ dopaminergic receptors in the developing chick retina. Autoradiographic experiments revealed that in retinas from 3-day-old chicken and embryos with 12, 14 and 16 days of development, specific labeling of ³H]SCH 23390 was mainly observed over the plexiform layers of the tissue, showing that dopaminergic D₁ receptors are localized in retina cell neurites since the initial stages of neurite formation. The total number of ³H]SCH 23390 binding sites increased 5-fold during the differentiation of the retina, while the dopamine-dependent cyclic adenosine monophosphate (AMP) accumulation was significantly decreased. Consequently, the ratio between dopamine-dependent cyclic AMP accumulation and ³H]SCH 23390 binding sites decreased 10-fold as retina differentiated, indicating that a significant portion of D₁ receptors in retinas from adult chicken are not effectively coupled to adenylate cyclase molecules.