DISTRIBUTION OF PARVALBUMIN-EXPRESSING NEURONAL POPULATIONS IN THE CAT CERVICAL AND LUMBAR SPINAL CORD GRAY MATTER

Abstract

Parvalbumin is a classical marker of interneuronal populations in the central nervous system. Analyzing the cervical and lumbar spinal cord segments of cats (Felis catus), both individual cells and entire populations of neurons expressing parvalbumin were identified in most of the gray matter laminae. These populations have strict laminar and nuclear localization. Numerous neuronal clusters are located in the medial part of lamina V–VI and in laminae VII of cervical and lumbar enlargements. We believe that the first one located in segments C4–C8 and L4–L7 may participate in the modulatory mechanisms of locomotor activity via the convergence of cutaneous and proprioceptive afferentation from the limbs. Neuronal populations in lamina VII consist of Ia interneurons and Renshaw interneurons that participate in the motoneuron inhibition. Less numerous populations of parvalbumin-immunopositive cells found in laminae III possibly participated in the regulation of cutaneous sensitivity. Another population located in lamina VIII possibly forms commissural and propriospinal connections and participates in modulating the activity of motoneurons. Immunopositive interneurons also revealed in the precerebellar nuclei: central cervical nucleus and Clarke’s nucleus; unlike the general population of these nuclei, neurons revealed are interneurons. Scarce immunopositive cells are found in lamina I of L6–L7 segments, as well as in laminae II, IV, and X of all segments investigated.