Primary cultures from defined brain areas; effects of seeding time on cell growth, astroglial content and protein synthesis.

The influence of seeding time on cell growth, astroglial content and on protein synthesis during cultivation was determined in primary cultures from 3 phylogenetically different brain areas from rat cerebral cortex, striatum and brainstem. Brainstem cultivated from 17-day-old embryos and all the cultures studied from the 3 brain areas of newborn and 7-day-old rat showed a similar increase in total and water-soluble protein during cultivation. Glial fibrillary acidic protein (GFAp, alpha-albumin) levels increased with age in all cultures studied. There was a rapid increase in GFAp (alpha-albumin) between 1 and 2 weeks in cultures from newborn and between 2 and 3 weeks in brainstem cultures from 17-day-old embryos, these increases being slower thereafter. Incorporation of [3H]valine into soluble protein was lower in 3-week-old cultures than in 1- and 2-week-old cultures derived from newborn and 7-day-old rat brain. The incorporation rates were similar in comparisons of the various cultures. Similar results were obtained from embryonic cultures, although the decrease in incorporation rate was between 3 and 4 weeks. The efficiency of incorporation (% TCA-precipitated material/total [3H]activity) was higher in 2- and 3-week-old than in 1-week-old cultures from newborn and 7-day-old rats and in 3- and 4-week-old cultures of brainstem from 17-day-old rat embryos. These findings suggest a cell differentiation during cultivation. The results show that seeding time has a variable influence on cultures from the different brain areas studied concerning cell growth, astroglial content and probably differentiation during cultivation. Embryonic cell cultures seem, in general, to develop one week later than neonatal and postnatal ones. Cultures of newborn rat cells from cerebral cortex, striatum and brainstem show many similarities in the above parameters during cultivation. This is also the case for brainstem cultures from embryonic rat.