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Preoptic catecholamine, GABA, and glutamate release in ovariectomized and ovariectomized estrogen-primed rats utilizing a push-pull cannula technique.
- Source :
-
Neuroendocrinology [Neuroendocrinology] 1985 Sep; Vol. 41 (3), pp. 212-8. - Publication Year :
- 1985
-
Abstract
- The push-pull cannula technique was used to evaluate the role of the medial preoptic/anterior hypothalamic area (MPO) in regulating pituitary luteinizing hormone (LH) and prolactin release. The concentrations of the three catecholamines--dopamine, norepinephrine (NE), epinephrine (E)--and gamma-aminobutyric acid (GABA) and glutamate could be measured in 15-min fractions at which interval blood samples for LH and prolactin determination were also collected. Comparison of neurotransmitter release rates into the MPO were made between ovariectomized and ovariectomized estradiol benzoate treated rats. Release of the neurotransmitters occurred in a pulsatile manner, the release episodes for each transmitter appeared to be independent of the others. No direct correlation between neurotransmitter release episodes and blood LH or prolactin levels could be established. The release of GABA was significantly lower and that of NE and E higher in ovariectomized animals in comparison to estrogen-primed ovariectomized animals under negative feedback conditions. In the afternoon, however, when the estrogen stimulated LH and prolactin release, preoptic GABA release was low, whereas preoptic NE and particularly E release rates were high. Conspicuously high dopamine and NE release episodes were observed in estrogen-primed animals at noon, i.e., prior to the expression of the positive feedback signal. This may reflect a biochemical correlate to the so-called critical period. No consistent differences between ovariectomized and ovariectomized estradiol-17 beta benzoate treated animals were observed for preoptic glutamate release rates. The data show that preoptic GABA release rates show generally an inverse pattern to NE and E release and therefore also to blood LH and prolactin levels. No direct mathematical correlation between any of the neurotransmitter release rates and blood hormone levels could be established.
- Subjects :
- Animals
Brain Chemistry drug effects
Catecholamines metabolism
Catheterization methods
Female
Glutamates metabolism
Glutamic Acid
Injections, Intraventricular
Jugular Veins
Luteinizing Hormone blood
Ovariectomy
Prolactin blood
Rats
Time Factors
gamma-Aminobutyric Acid metabolism
Estradiol administration & dosage
Neurotransmitter Agents metabolism
Preoptic Area metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0028-3835
- Volume :
- 41
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Neuroendocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 2864651
- Full Text :
- https://doi.org/10.1159/000124180