CALCITONIN GENE-RELATED PEPTIDE (CGRP) IMMUNOREACTIVITY IN THE AFFERENTS TO THE CAUDATE-PUTAMEN AND PERIRHINAL CORTEX OF RATS

The posterior caudate-putamen and perirhinal cortex innervated by fibers immunoreactive to calcitonin gene-related peptide (CGRP). We investigated the origin of these fibers by using immunohistochemically combined with lesion experiments and fluorescent dye tracers. Lesions of the posterior thalamus surrounding the medial geniculate nucleus, in which groups of CGRP-like immunoreactive (CGRP-LI) cells exist, decreased the number of ipsilaterally CGRP-LI fibers in the posterior caudate-putamen and partly in the perirhinal cortex. Some of CGRP-LI neurons in several posterior thalamic nuclei surrounding the medial geniculate nucleus were labeled with both Fast blue injected into the posterior caudate-putamen and fluoro-gold administered into the anterior perirhinal cortex. Our results indicate that CGRP-LI cells in the posterior thalamus, such as posterior intralaminar, lateral subparafascicular and subparafascicular nuclei, project neither separately or simultaneously to innervate the posterior caudate-putamen and perirhinal cortex.