Depletion of biogenic amines and enhancement of cholinergic activity in the olfactory bulb and central olfactory connections with chronic methedrine intoxication

Abstract

Macrosmatic animals under the influence of chronic doses of ampheta mine develop stereotyped patterns of sniffing, looking, gnawing and grooming. The most prominent stereotopy in cast is repetitive sniffing. The purpose of this report is to present evidence of histochemical changes in the olfactory system of cats, which had developed a marked sniffing stereotopy with pro longed methedrine treatment. MATERIAL AND METHODSA group of 12 cats weighing 2 to 3 kg. was studied. The animals were injected twice daily with increasing doses of methedrine 7.5-40 mg/kg for 10 days. The whole brain was dissected from the animal under a light pentobarbital anesthesia. Selected blocks of fresh tissue were immediately frozen in liquid nitrogen. The tissue was then processed histochemically to develop biogenic amine fluorescence and the cholinergic reaction, using procedures of Falck and Hillarp 6 and Karnovsky and Roots 1 as well as our modification of both histochemical techniques (Duarte-Escalante et al. 3 , 4 ). RESULTSIn the normal adult cat, the cytoarchitectony of the olfactory bulb resembles the pattern of other mammals such as the rabbit and guinea pig. A few differences are observed in the increased number of afferent fibers ending at the olfactory glomeruli and in the fibers connecting the mitral, tufted and granular cells which appear to be multibranched in the cat. Using the fluorescent technique, adrenergic varicosities of medium to large size (1-2 microns) are observed around