title: Triiodothyronine increases glutamine synthetase activity in primary cultures of rat cerebellum.
abstract: Dissociated cells from 2-3 day-old rat cerebella were cultured in absence of thyroid hormones using conditions yielding mainly glial cells. After 7, 14 and 21 days in vitro, triiodothyronine (60 nM) was added to a set of dishes and glutamine synthetase activity was measured after 24, 48, and 72 h in both control and triiodothyronine-treated cultures. Basal glutamine synthetase activity increased more than 6 X between 7 and 21 days of culture. Triiodothyronine produced significant increases of glutamine synthetase activity after 72 h in 7-day-old cultures (+ 16%), after 48 h in 14-day-old cultures (+ 45%) and after 24 h in 21-day-old cultures (+ 27%). This effect depends on the initial plating density and is not observed if cells are plated at less than 1 cerebellum equivalent per 60 mm dish. Dose-response experiments indicated that 10(-8) M of triiodothyronine induces maximal response whereas half-maximal response is achieved around 10(-10) M. These results show that physiological amounts of thyroid hormone can influence the maturation of astrocytes in culture.
authors.forename: J
authors.initials: J
authors.lastname: Ruel
authors.forename: J H
authors.initials: JH
authors.lastname: Dussault
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000201:enzymology*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D009457:Neuroglia / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D014284:Triiodothyronine / Q000494:pharmacology*
chemical_list: D014284:Triiodothyronine; D005974:Glutamate-Ammonia Ligase