Ontogenesis of serotonergic systems in rat brain

It was shown that the concentration of brain 5-HT rises slowly, reaching mature values by 80 days of age, while the catabolic product of 5-HT, i.e., 5-HIAA, drops from a high perinatal value to lower values by adulthood. This is indicated of poorly developed storage mechanisms at this early period in life. It was also shown that MAO develops at a rapid rate, acquiring mature values by 20 days. The activity of MAO towards substrates develops at different rates, although the general pattern of development is the same.

Diurnal rhythm in endoplasmic reticulum of rat liver: electron microscopic study

Electron microscopy of rat hepatocytes revealed a diurnal variation in the relative amounts of endoplasmic reticulum structures and regional differences in their distribution within the hepatic lobule. The diurnal changes in smooth and rough endoplasmic reticulum structures were compared with the diurnal changes in the hepatic microsomal enzyme hexobarbital oxidase. In the control group, at the time when enzyme activity was maximum, the amount of smooth endoplasmic reticulum was also maximum and vice versa. When the enzyme rhythm was abolished, as in blinded rats, the diurnal rhythm in the endoplasmic reticulum was also abolished.