GLUTAMINE TRANSAMINASE-K AND OMEGA-AMIDASE ACTIVITIES IN PRIMARY CULTURES OF ASTROCYTES AND NEURONS AND IN EMBRYONIC CHICK FOREBRAIN - MARKED INDUCTION OF BRAIN GLUTAMINE TRANSAMINASE-K AT TIME OF HATCHING
Tk. Makar et al., GLUTAMINE TRANSAMINASE-K AND OMEGA-AMIDASE ACTIVITIES IN PRIMARY CULTURES OF ASTROCYTES AND NEURONS AND IN EMBRYONIC CHICK FOREBRAIN - MARKED INDUCTION OF BRAIN GLUTAMINE TRANSAMINASE-K AT TIME OF HATCHING, Journal of neurochemistry, 62(5), 1994, pp. 1983-1988
Glutamine transaminase K and omega-amidase activities are present in t
he chick brain and in the brains of adult mice, rats, and humans. Howe
ver, the activity of glutamine transaminase K in adult mouse brain is
relatively low. In the chick embryo, cerebral glutamine transaminase K
activity is low between embryonic days 5 and 17, but by day 23 (day o
f hatching) activity rises dramatically (> 15-fold). Cerebral omega-am
idase activity is relatively high at embryonic day 5 but lower between
days 5 and 17; at embryonic day 23 the activity rises to a maximum. B
oth glutamine transaminase K and omega-amidase are present in cultured
chick, rat, and mouse astrocytes and neurons. For each species, the a
ctivity of glutamine transaminase K is higher in the astrocytes than i
n the neurons. The activity of omega-amidase is about the same in the
cultured chick astrocytes and neurons but significantly higher in rat
astrocytes than in rat neurons. The data suggest that the rise in brai
n glutamine transaminase K activity in the chick embryo at hatching co
rrelates with maturation of astrocytes. Glutamine transaminase K may b
e involved in glutamine cycling in astrocytes. Glutamine transaminase
K appears to be a major cysteine S-conjugate beta-lyase of the brain a
nd may play a role in the neurotoxicity associated with exposure to di
chloroacetylene and perhaps to other toxins.