Quantitative Change of Dopamine in the Tuberohypophyseal Tract of the Rat under Some Experimental Conditions

Abstract

Alterations in the content of primary catecholamines, especially dopamine, in the tractus tuberohypophyseus were studied in male albino rats under several experimental conditions by a histochemical fluorescence method for biogenic amines.
1. Dopamine in the tractus tuberohypophyseus completely disappeared after the administration of reserpine, while nialamide and L-dopa administration intensified dopamine specific green fluorescence in all varicose fibers of the infundibulum.
2. The content of dopamine in the tuberohypophyseal tract was altered during the following three experiments. Bilateral adrenalectomy induced an abrupt increase in the amount of dopamine. This increase in dopamine was suppressed by postoperative administrations of dexamethasone (5mg/day for 16 days). The amount of dopamine was also distinctly decreased in the case of the administration of dexamethasone (5mg/day for 16 days) without adrenalectomy.
3. Hypophysectomy resulted in a remarkable increase in the catecholamine content of the infundibulum.
4. Bilateral orchiectomy resulted in a slight increase in catecholamine in the external layer of the infundibulum.
5. The administration of histamine induced a marked decrease of monoamines in the median eminence. On the basis of these results the biological correlation between biogenic amines in the median eminence and regulating factors for the adenohypophysis was discussed.