CONTRIBUTION OF GLIAL-CELLS TO HISTAMINE INACTIVATION

dl-α-aminoadipic acid (dl-αAA), a selective gliotoxic agent produced significant reductions in histamine-N-methyl-transferase (HNMT) and monoamine oxidase-B (MAO-B) activities and an enhancement in histamine (HA) level in the hypothalamus of rats 2 and 4 h after single intracerebroventricular (i.c.v.) or subcutaneous (s.c.) injections of the compound. Histidine decarboxylase (HD) and monoamine oxidase-A (MAO-A) were unaffected after these treatments. Following a single i.c.v. injection of dl-αAA of 200 μg/rat, or a single s.c. injection of 5 mg/rat, marked diminutions in the astrocytic marker glutamine synthetase (GS) activity occured suggesting marked glial damage in the hypothalamus. In total, these studies indicate an important role for glial cells in HA metabolism (inactivation). © 1990 Birkhäuser Verlag.