ISSN:
1432-0878
Keywords:
Key words: Secretory granules – Golgi apparatus – Haloperidol – Ultrastructure – Pituitary gland, pars intermedia – Rat (Sprague Dawley)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract. The formation of secretory granules in chronically hypersecretory melanotrophs in the rat pituitary was studied. Hypersecretion was induced by treatment with the dopamine antagonist haloperidol (1.5 mg/kg daily for 7 days), which releases the normal neural dopaminergic inhibition of secretion from the melanotroph. Morphometric analysis showed a 100% increase in the volume fraction of granular endoplasmic reticulum after haloperidol treatment, while the volume fractions of electron-dense granules, electron-lucent granules and the Golgi apparatus were unaltered. The mean diameter of the mature secretory granules was increased by 10%, indicating a 30% increase in mean granule volume. A similar increase in diameter was observed in condensing granules within the Golgi area. With earlier results on the effect of chronic inhibition the study shows that a main adaptive response of the melanotroph to altered secretory conditions is a change in the volume of the secretory granules, regulated by a mechanism that operates at an early stage of granule formation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00319432
