Activity and Distribution of Five Digestive Enzymes in the Gut of Gryllotalpa Gryllotalpa Curtis (Gryllotalpidae: Orthoptera) After Allatectomy, Brain Cauterization and Juvenoid Treatment

A study was made on the effects of allatectomy, brain cauterization and juvenoid treatment on the activities and distribution of protease, amylase, lipase, trypsin and chymotrypsin in various regions of the gut of the adult mole-cricket, Gryllotalpa gryllotalpa (Curtis). Allatectomy resulted in a significant reduction in the amount of protease, lipase, trypsin and chymotrypsin enzyme activity. Brain cauterization produced the same effect, but amylase and lipase activity also decreased. Juvenoid treatment of allatectomized insects reversed the effect of allatectomy; in addition, the distribution pattern of the enzyme activity was changed in different regions of the gut. The results are discussed in relation to the neuroendocrine control of enzyme secretion and synthesis.

Effect of brain monoamines on the secretion of adrenocorticotrophic hormone

The role of brain monoamines (5-HT, NA and DA) in the secretion of adrenocorticotrophic hormone (ACTH) was studied in view of contradictory reports. Plasma corticosterone levels and the rate of synthesis of corticosterone in vitro by the adrenal gland were estimated in albino rats and have been taken as the index of ACTH activity. These estimations were done in unstressed and stressed, and in untreated and treated rats. Drugs were administered intracerebroventricularly to the rats to cause selective degeneration of tryptaminergic, noradrenergic or dopaminergic neurons. The results show that plasma corticosterone levels and the rate of synthesis of corticosterone were significantly decreased after selective degeneration of tryptaminergic neurons in unstressed rats. After selective degeneration of either tryptaminergic or noradrenergic neurons, the acute increase in the plasma corticosterone levels and rate of synthesis of corticosterone in vitro by adrenal glands in stressed rats were significantly inhibited. These results have been interpreted to suggest that the central tonic control on adrenal glands may be 5-HT mediated and that during stress ACTH secretion may be both 5-HT and NA mediated. DA does not seem to have significant role in the regulation of ACTH secretion.

Succinate dehydrogenase, monoamine oxidase and glutamine synthetase in developing human foetal brain regions

In human foetal brain ontogeny the cerebral activity of succinate oxidoreductase (EC 1.3.99.1), i.e. succinate dehydrogenase (SDH), is higher than the cerebellar activity. With rise in foetal body weight the activity in all the brain regions gradually declines. SDH in all the brain regions shows two high-activity periods, one at 20-35 g and another at 110-220 g body weight. The enzyme exhibits a craniocaudal pattern of development. At all times of gestation, L-glutamate:ammonia ligase (EC 6.3.1.2), i.e. glutamine synthetase, activity in the spinal cord and medulla is higher than in the other three regions. At 190 g body weight glutamine synthetase shows an activity peak in all brain regions. Monoamine:oxygen oxidoreductase (EC 1.4.3.4). i.e. monoamine oxidase (MAO), is present much before the onset of electrical activity. It develops caudocranially and exhibits a biphasic pattern of development in all the regions. It increases considerably in the medulla and the spinal core towards late gestational periods.