Systemic glutamate induces degeneration of a subpopulation of tyrosine hydroxylase-immunoreactive neurons in the rat area postrema.

Neuronal damage in the area postrema (AP) of 12-14-week-old male rats was induced by subcutaneous administration of monosodium glutamate (MSG). An immunocytochemical method was used to visualize catecholaminergic neurons in the AP after MSG-treatment. Some tyrosine hydroxylase-immunoreactive neurons exhibited marked signs of degeneration, while others appeared undamaged. We conclude that catecholamine-synthesizing neurons in the AP are differentially sensitive to the neuroexcitotoxic effect of systemic glutamate.