The Effects of Guanethidine, Pre‐ and Postganglionic Nerve Division on the Rat Superior Cervical Ganglion: Cholinesterases and Catecholamines (Histochemistry), and Histology

Guanethidine administered intraperitoneally in a dose of 20 mg/kg for 5 to 14 days induced a considerable reduction of histochemically demonstrable specific and non‐specific cholinesterases. The loss initially involved the cytoplasm of the ganglion cells, but following prolonged administration there was a complete loss which also involved the nerve fibres. After guanethidine 1–25 mg/kg an increasing degree of chromatolysis of the sympathetic ganglion cells was observed accompanied by infiltration of small cells. The increased number of small cells caused an increase in ganglionic size of approximately 50 % (guanethidine 20 mg/kg for 14 days). The increased number of small cells mainly consisted of small lymphocyte — like cells, some of which showed pyroninophilia, and of macrophages. Mitoses were not observed, and the number of Schwann cells appeared unchanged. The possibility of an immunological process is discussed. The changes appeared to be specific, as only sympathetic ganglion cells were involved. These changes were partly reversible, though a number of ganglion cells had undergone complete degeneration. The ganglionic noradrenaline was partially depleted by guanethidine. The alterations induced by guanethidine resembled those resulting from postganglionic axotomy, but they developed independently of previously performed pre‐ or postganglionic nerve division. It is suggested that guanethidine has a direct effect on the ganglion cells.