GABAergic biochemical parameters of the tuberoinfundibular neurons following chronic hyperprolactinemia.
The effect of chronic hyperprolactinemia was studied on (a) GABA concentration in the pituitary anterior lobe; (b) GABA biosynthesis enzyme, glutamate decarboxylase (GAD) activity in the hypothalamic median eminence, and (c) GABA degradation enzyme GABA-transaminase (GABA-T) activity at both levels. In male rats bearing the prolactin-secreting tumor MtTF4 for 1 month or treated for 5 days with estradiol benzoate, the plasma prolactin concentration was markedly increased (between 4- and 10-fold basal values). In both cases, GABA concentration was significantly increased (40-60%) in the anterior pituitary lobe. A slight reduction (20-30%) in GABA-T activity was observed in the anterior lobe while no change in GAD or GABA-T activity was measured in the median eminence. These results are discussed in relationship to a possible feedback input of prolactin on the tuberoinfundibular GABAergic system.
Felman
K
K
INSERM U 171, CNRS UA 1195, Centre Hospitalier Lyon-Sud, Pierre Bénite, France.
Tappaz
M
M
D000612:4-Aminobutyrate Transaminase / Q000378:metabolism; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006966:Hyperprolactinemia / Q000201:enzymology / Q000378:metabolism*; D007031:Hypothalamus / Q000201:enzymology / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D015175:Prolactinoma / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011919:Rats, Inbred Strains; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; D005968:Glutamate Decarboxylase