Morphology and Topographic Distribution of Calbindinergic and Parvalbuminergic Neurons in the Rabbit Cervical Cord

Kim, Young Ju; Moon, Dong Eon; Kim, Oon Sung; Lee, Yun Ki

Abstract

In transmembrane and intracellular sites of neurom, calcium ion(Ca(++)) has been known to have an important role of signalling process. It is naw well accepted that calcium binding proteins, calbindin D-28K (calbindin) and parvalbumin, modulate and mediate above aclcium ionss action as a second messenger. Although it has been reported that calbindinergic and parvalbuminergic neurons comprise different subpopulations in the cat and rat spinal cords, the studies of their morphology, topographical distribution and ultrastructural features have not been done extensively in the mammalian spinal cords until now. This study was conducted to localize calbidinergic and parvalbuminergic neurons and to define their morphology, topographical distribution and ultrastructural features in the rabbit cervical cord by the preembedding immunocytochemical method using anti-calbindin and anti-parvalbumin antisera. In the rabbit cervical cord, calbindin immunoreactive neurons were mainly distributed in the dorsal horn, especially in lamina II, and a smaI1 number of labelled neurons were observed in the intermediate gray matter (IGS), but calbindin immunoreactivities were not observed in the intermediate gray substance(IGS), but calbindin immunoreactiveties were not observed in thr ventral horn. The somata of calbindin immunoreactive neurons received synaptic inputs from non-immunoreactive axon terminals in the dorsal horn and in the IGS. Parvalbumin immunoreactive neurons were mainly observed in the IGS and in the ventral horn, but only a few of parvalbumin immunoreactive neurons were distributed in the dorsal horn. In the ventral horn, two types of parvalbumin immunoreactive neurons were identified according to the sizes of the somata and labelled motor cells received synaptic inputs from labelled and unlabelled axon terminals. These results demonstrate that calbindinergic neurons are a number of neurons located in lamina II of dorsal horn and a few of neurons located in the intermediate gray and parvalbuminergic ne.urons are laocated in the intermediate gray substance and in the ventral horn, and these neurons comprise different subpopulations of neurons. It was suggest that calbindinergic neurons might play an important role in the process of pain modulation and parvalbumiergic neurons in the control of motor activity with their specific synaptic circuitry in the spinal cord.