The acetylcholinesterase activity, RNA levels, total free amino acids and magnesium content in fore-, mid- and hind-brain were determined in the normal and hypophysectomised frogs (Rana cyanophlyctus). Hypophysectomy results in a marked decrease in the freea−a and in Mg. RNA also decreases significantly, but not to the same degree as thea−a and Mg. But AchE levels do not change significantly although there is a general decrease. It is suggested that the decrease in Mg is a reflection of the ionic imbalance resulting from hormonal imbalance. Hypophysectomy also results in reduced protein synthesis (and/or turnover) in the CNS as indicated by reduced RNA anda−a
