Localization of carbonic anhydrase in identified glial cells of the leech central nervous system: application of histochemical and immunocytochemical methods.

We localized the enzyme carbonic anhydrase (CA) in frozen sections of the leech (Hirudo medicinalis) central nervous system by two histochemical techniques and the indirect immunofluorescence technique. Hansson's cobalt precipitation method and the use of 1-dimethylamino-naphthalene-5-sulfonamide (DNSA) to build a fluorescent enzyme-substrate complex showed that glial cells are the sites of CA activity in the leech. Neuropil and connective glial cells surrounding the axons had strong CA activity, whereas packet glial cells, which surround neuron cell bodies, and neurons themselves remained unstained. Glial cells reacted markedly with FITC-coupled antibodies against CA isoenzyme II, but experiments with antibodies against CA isoenzyme I showed no reaction.