Hypothalamic and limbic GABA concentrations and turnover rates and glutamate concentrations following induction of hyperprolactinemia in ovariectomized rats.
Hyperprolactinemia was induced by transplantation of pituitaries of donor rats under the kidney capsule of ovariectomized recipient rats. This results in a permanently increased serum prolactin and temporarily suppressed luteinizing hormone (LH) levels. Concentrations of gamma-aminobutyric acid (GABA) and glutamate as well as turnover rates of GABA were determined in micropunches of the nucleus accumbens (ACB), medial preoptic area (MPO), anterior and posterior part of the mediobasal hypothalamus (AMBH and PMBH) and in the mediocortical amygdala (AMY). GABA concentration in the ACB and MPO were reduced in hyperprolactinemic rats. This was significant at day 8. At days 4 to 21 following pituitary transplantation glutamate concentrations were also significantly reduced in the AMY. The most conspicuous changes in GABA turnover rates were observed in the ACB and MPO. In the former structure hyperprolactinemia reduced GABA turnover, while in the latter high prolactin levels increased GABA turnover at day 4. It is concluded that the suppressive effect of hyperprolactinemia on blood LH levels may involve a preoptic GABAergic component and possibly a glutamatergic mechanism in the AMY. Alternatively, the AMY and the ACB may be involved in eliciting the many behavioral effects associated with hyperprolactinemia.
D000818:Animals; D002369:Castration; D005260:Female; D005971:Glutamates / Q000032:analysis*; D007031:Hypothalamus / Q000032:analysis* / Q000378:metabolism; D008032:Limbic System / Q000032:analysis* / Q000378:metabolism; D011301:Preoptic Area / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000032:analysis* / Q000378:metabolism
D005971:Glutamates; D005680:gamma-Aminobutyric Acid; D011388:Prolactin