The inferior colliculus: calbindin and parvalbumin immunoreactivity in neural grafts

The inferior colliculus was selected as a brain stem site for study of neural grafting and identification of calcium binding proteins. Unilateral ablation sites of eight midbrain inferior colliculus in adult Long-Evans rats were implanted with E17-18 caudal tectum. After 2 to 9 months animals were sacrificed and sections reacted using antibodies for calbindin and parvalbumin. The central nucleus of normal inferior colliculus shows high density of neuronal and fiber staining for parvalbumin. Typical graft cores had similar staining distributions including discoid and stellate neuron populations. Graft cores showed low densities of reactivity for calbindin comparable to central nucleus. In surrounding graft regions there was substantive-neuronal and fiber labeling for calbindin and parvalbumin including stellate neuron populations normally found in the dorsal and lateral nuclei of inferior colliculus. These results demonstrate that the expression of calcium binding proteins in tectal grafts resembles that of inferior colliculus.