Summary
The morphological effect of chronic synthetic and secretory inhibition of the intermediate lobe of the rat pituitary induced by bromocriptine treatment was studied using morphometric techniques in combination with electron microscopy. On the basis of granule diameters, a heterogeneous cell population was shown in the normal intermediate lobe. Bromocriptine treatment did not induce any change in the volume fraction, number or location of electron-dense secretory granules. Instead, there was a shift toward a more homogeneous cell population containing smaller granules, the mean granule volume being reduced by ∼30%. The volume fraction of electron-lucent granules or vacuoles was markedly reduced, indicating a functional significance of these organelles. The volume of the Golgi apparatus was not significantly altered, but the number of condensing granules within the Golgi area was reduced. The volume of the intermediate lobe was decreased, apparently due to a decrease in the mean cell volume.
Similar content being viewed by others
References
Aherne WA, Dunnill MS (1982) Morphometry. Edward Arnold, London
Autelitano DJ, Smith AI, Lolait SJ, Funder JW (1985) Dopaminergic agents differentially alter β-endorphin processing patterns in the rat pituitary neurointermediate lobe. Neurosci Lett 59:141–146
Baumgarten HG, Björklund A, Holstein AF, Nobin A (1972) Organization and ultrastructural identification of the catecholamine nerve terminals in the neural lobe and pars intermedia of the rat pituitary. Z Zellforsch 126:483–517
Bcaulieu M, Goldman ME, Miyazaki K, Frey EA, Eskay RL, Kebabian JW, Cote TE (1984) Bromocriptine-induced changes in the biochemistry, physiology, and histology of the intermediate lobe of the rat pituitary gland. Endocrinology 114:1871–1884
Beaulieu M, Felder R, Kebabian JW (1986) D-2 dopaminergic agonists and adenosine 3′,5′-monophosphate directly regulate the synthesis of α-melanocyte-stimulating hormone-like peptides by cultured rat melanotrophs. Endocrinology 118:1032–1039
Bendayan M, Bruneau A, Morisset J (1985) Morphometrical and immunocytochemical studies on rat pancreatic acinar cells under control and experimental conditions. Biol Chem 54:227–234
Cannata MA, Morris JF (1973) Changes in the appearance of hypothalamo-neurohypophysial neurosecretory granules associated with their maturation. J Endocrinol 57:531–538
Chen CLC, Dionne FT, Roberts JL (1983) Regulation of the proopiomelanocortin mRNA levels in rat pituitary by dopaminergic compounds. Proc Natl Acad Sci USA 80:2211–2215
Chrétien M, Boileau G, Lazure C, Seidah NG (1984) Processing of peptide hormone and neuropeptide precursors. In: Cantin M (ed) Cell biology of the secretory process. S Karger, Basel New York, pp 214–246
Chronwall BM, Millington WR, Griffin ST, Unnerstall JR, O'Donohue TL (1987) Histological evaluation of the dopaminergic regulation of proopiomelanocortin gene expression in the intermediate lobe of the rat pituitary, involving in situ hybridization and (3H)thymidine uptake measurement. Endocrinology 120:1201–1211
Clivelli O, Douglass J, Herbert E (1984) Pro-opiomelanocortin: A polyprotein at the interface of the endocrine and nervous systems. In: Gross E (ed) The peptides, vol 6. Academic Press, New York, pp 69–94
Cote TE, Eskay RL, Frey EA, Grewe CW, Munemura M, Stoof JC, Tsuruta K, Kebabian JW (1982) Biochemical and physiological studies of the beta-adrenoreceptor and the D-2 dopamine receptor in the intermediate lobe of the rat pituitary gland: A review. Neuroendocrinology 35:217–224
Cote TE, Felder R, Kebabian JW, Sekura RD, Reisine T, Affolter H-U (1986) D-2 dopamine receptor-mediated inhibition of proopiomelanocortin synthesis in rat intermediate lobe. J Biol Chem 261:4555–4561
Douglas WW (1968) Stimulus-secretion coupling: the concept and clues from chromaffin and other cells. Br J Pharmacol 34:451–474
Eipper BA, Mains RE, Herbert E (1986) Peptides in the nervous system. Trends Neurosci 9:463–468
Gainer H, Russell JT, Loh YP (1985) The enzymology and intracellular organization of peptide precursor processing: the secretory vesicle hypothesis. Neuroendocrinology 40:171–184
Hassoun J, Jaquet P, Devictor B, Andonian C, Grisoli F, Gunz G, Toga M (1985) Bromocriptine effects on cultured human prolactin-producing pituitary adenomas: in vitro ultrastructural, morphometric, and immunoelectron microscopic studies. J Clin Endocrinol Metab 61:686–692
Landolt AM, Osterwalder V, Landolt TA (1987) Storage and release of secretory granules in human prolactionomas: modification by bromocriptine. J Endocrinol 113:495–499
Larsson L-I (1986) Histochemistry of gastrin cells. In: Neurohistochemistry: Modern methods and applications. Alan R Liss, New York, pp 527–567
Lederis K (1974) Neurosecretion and the functional structure of the neurohypophysis. In: Greep RO, Astwood EB (eds) Handbook of Physiology, Sect 7, vol. IV: The pituitary gland and its neuroendocrine control, part I. Williams and Wilkins, Baltimore, pp 81–102
Locatelli V, Petraglia F, Penalva A, Panerai AE (1983) Effect of dopaminergic drugs on hypothalamic and pituitary immunoreactive β-endorphin concentrations in the rat. Life Sci 33:1711–1717
Loh YP, Gritsch HA, Chang T-L (1982) Pro-opiocortin processing in the pituitary: a model for neuropeptide biosynthesis. Peptides 3:397–404
Martin R, Weber E, Voigt KH (1979) Localization of corticotropin- and endorphin-related peptides in the intermediate lobe of the rat pituitary. Cell Tissue Res 196:307–319
Millington WR, Maiewski S, O'Donohue TL, Mueller GP (1985) Long-term haloperidol treatment elevates β-endorphin levels in the intermediate pituitary but not in rat brain. Neuropeptides 6:365–372
Moriarty GC (1973) Adenohypophysis: ultrastructural cytochemistry. A review. J Histochem Cytochem 21:855–894
Morris JF, Nordmann JJ (1982) Membrane retrieval by vacuoles after exocytosis in the neural lobe of Brattleboro rats. Neuroscience 7:1631–1639
Morris JF, Nordmann JJ, Dyball REJ (1978) Structure-function correlation in mammalian neurosecretion. Int Rev Exp Pathol 18:1–95
Munemura M, Cote TE, Tsuruta K, Eskay RL, Kebabian JW (1980) The dopamine receptor in the intermediate lobe of the rat pituitary gland: pharmacological characterization. Endocrinology 107:1676–1683
O'Donohue TL, Dorsa DM (1982) The opiomelanotropinergic neuronal and endocrine systems. Peptides 3:353–395
Pelletier G, Leclerc R, Benjannet S, Seidah NG, Chrétien M (1981) Immunohistochemical localization of γ-melanocyte-stimulating hormone in the rat pituitary gland. Regul Pept 2:81–89
Saltykov SA (1967) The determination of the size distribution of particles in an opaque material from a measurement of the size distribution of their sections. Proceedings of the 2nd International Congress for Stereology, Chicago. Springer, Berlin Heidelberg New York
Simson JAV, Spicer SS, Hall BJ (1974) Morphology and cytochemistry of rat salivary gland acinar secretory granules and their alteration by isoproterenol. I. Parotid gland. J Ultrastruct Res 48:465–482
Stachura ME, Tyler JM (1987) Growth hormone-releasing factor-44 specificity for components of somatotroph and lactotroph immediate release pool substructures. Endocrinology 120:1719–1726
Stachura ME, Costoff A, Tyler JM (1986) Structural correlates of stimulated and inhibited secretion: Electron microscopic observations of somatotrophs in perfused rat pituitary. Neuroendocrinology 42:383–391
Stoeckel ME, Schmitt G, Porte A (1981) Fine structure and cytochemistry of the mammalian pars intermedia. In: Evered D, Lawrenson G (eds) Peptides of the pars intermedia. Ciba Foundation Symposium 81. Pitman Medical, London, pp 101–127
Swann RW, Pickering BT (1976) Incorporation of radioactive precursors into the membrane and contents of the neurosecretory granules of the rat neurohypophysis as a method of studying their fate. J Endocrinol 68:95–108
Tilders FJH, Berkenbosch F, Smelik PG (1985) Control of secretion of peptides related to adrenocorticotropin, melanocytestimulating hormone and endorphin. Front Horm Res 14:161–196
Uylings HBM, Eden CG van, Hofman MA (1986) Morphometry of size/volume variables and comparison of their bivariate relations in the nervous system under different conditions. J Neurosci Meth 18:19–37
Weibel ER (1979) Stereological methods. Vol 1. Practical methods for biological morphometry. Academic Press, London
Weibel ER, Gomez DM (1962) A principle for counting tissue structures on random sections. J Appl Physiol 17:343–348
Willingham MC, Pastan I (1980) The receptosome: an intermediate organelle of receptor-mediated endocytosis in cultured fibroblasts. Cell 21:67–77
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bäck, N. The effect of bromocriptine on the intermediate lobe of the rat pituitary: an electron-microscopic, morphometric study. Cell Tissue Res. 255, 405–410 (1989). https://doi.org/10.1007/BF00224124
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00224124