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Comparative Characterization of Glutamate Decarboxylase in Crude Homogenates of Oviduct, Ovary, and Hypothalamus
Author(s) -
Erdő Sándor L.,
Kiss Béla,
Szporny László
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb06074.x
Subject(s) - oviduct , glutamate decarboxylase , hypothalamus , endocrinology , medicine , glutamate receptor , ovary , gabaergic , biology , ovulation , chemistry , enzyme , biochemistry , inhibitory postsynaptic potential , hormone , receptor
Some biochemical characteristics of l ‐glutamate decarboxylase (GAD) were compared using crude homogenates of the rat oviduct, ovary, and hypothalamus. As estimated by the measurement of CO 2 production, the specific activities of oviductal and ovarian GAD were about 10 and 3% of the hypothalamic value, respectively. Stoichiometric formation of γ‐aminobutyric acid (GABA) and CO 2 from l ‐glutamate could be observed in oviduct and hypothalamus, while in ovarian homogenates the production of C0 2 was more than nine times that of GABA. Hypothalamic and tubal GAD showed similar time course, temperature dependence, and pH dependence. The dependence on protein concentration and on exogenous cofactor supply was also similar in these two tissues. The kinetic constant for l ‐glutamate as a substrate was nearly the same in oviduct (1.30 m M ) and hypothalamus (1.64 m M ). The responsiveness of tubal and hypothalamic GAD to various inhibitors was also similar. The present findings indicate that the oviductal and the hypothalamic GAD may be identical, and they suggest a possible GABAergic innervation of the Fallopian tube.