Ultrastructural immunolocalization of adenosine deaminase in histaminergic neurons of the tuberomammillary nucleus of rat.

ABSTRACT

Neurons in the tuberomammillary nucleus (TM) of the rat hypothalamus were immunolabelled for the enzyme adenosine deaminase (ADA) and investigated by electron microscopic immunohistochemical techniques. ADA-immunoreactivity was distributed throughout the somal and dendritic cytoplasm of TM neurons and in the karyoplasm of most, but not all of these neurons. Immunoreactive axons were rarely observed within the tightly packed cell clusters of the TM subdivisions examined. Dense deposition of immunoreaction product together with reasonable preservation of morphological detail facilitated identification of immunoreaction product together with reasonable preservation of morphological detail facilitated identification of immunoreactive profiles and allowed characterization of the ultrastructural features of labelled neurons and the relationships of these with each other and with surrounding unlabelled neuronal and glial elements. Immunolocalization of ADA therefore represents a reliable and convenient method for the identification of TM neurons in EM studies of their ultrastructure and synaptic interactions.