[Intracerebral picibanil injection in the rat neurogenic tumor--its histopathological changes]

Penicillin-free-Picibanil was injected into the brain of Wistar/Fibiger strain rat to investigate the histological changes. Its effect on the growth of rat schwannoma inoculated in the brain was also examined histologically. Picibanil caused the most prominent but focal lymphoreticular cell reaction around the injected site in the brain 24 to 48 hours after injection. The cells infiltrating from the blood vessels were neutrophils, monocytes, lymphocyte-like cells, histiocyte-like cells and unidentified cells. This lympho-reticular cell reaction gradually subsided in the next 4 to 5 days. Neutrophils and monocytes (macrophages)stayed till the later phase. Two weeks later, the lesion was minimal with only mild glial changes. Picibanil was however, considered to exert at the site of injection neurotoxic and glia-toxic activity at a concentration of 0.1 KE/10 microliters. The rat schwannoma (T1) cells, when inoculated without any treatment, showed vivid growth in the brain and no lympho-reticular cell reaction was observed. When the T1 tumor cells, suspended in the Picibanil solution, were inoculated into the brain, no lymph-reticular cell reaction was observed 7 and 14 days after inoculation. However, when the rat was pretreated with Picibanil into the brain 7 days before inoculation, only a mild lymphoreticular cell reaction was observed around the T1 cells till 7 days after inoculation. Accordingly, Picibanil was considered to induce nonspecific immunological in the rat brain even around the glioma.