Abstract
The priming effect of Luteinizing Hormone Releasing Hormone (LHRH), ie. the capacity of LHRH to increase the responsiveness of pituitary gonadotrophs to itself, is an important component of the mechanism by which changes in output of gonadotrophins during the oestrous cycle, in particular the preovulatory luteinizing hormone (LH) surge are controlled (Fink, 1979). LHRH priming can be elicited both in vivo (rat: Aiyer et al., 1974a; Fink et al.,1976; mouse: Fink et al., 1982) and in vitro (Pickering and Fink, 1976a; Waring and Turgeon, 1980). It is specific to LHRH and not elicited by secretagogues such as 40 mM K+ (Pickering and Fink, 1976b) and is not dependent on the initial release of LH (which normally occurs during the same 1h period as LHRH priming), since it occurs when LH release is blocked by removing calcium from the incubation medium (Pickering and Fink 1979). The priming effect of LHRH requires the synthesis of new protein (Pickering and Fink, 1979; Curtis et al., 1985) which is not LH (de Koning et al., 1976; Pickering and Fink, 1976a, 1979), and is dependent on the functional integrity of microfilaments (Pickering and Fink, 1979; Lewis et al., 1985). However, the subcellular mechanisms whereby the readily releasable pool of gonadotrophin is increased are still poorly understood. Previous ultrastructural analyses of LHRH stimulated gonadotrophs in vivo (Rommler et al., 1978) and in vitro (Tixier-Vidal et al., 1975; Childs, 1985) have reported changes in the position of granules but this has not been systematically or quantitatively analysed with respect to the priming effect of LHRH. The purpose of this report is to describe a series of quantitative ultrastructural analyses of gonadotrophs in different experimental and physiological states related to the augmented responsiveness of gonadotrophs produced by LHRH priming. The experiments have used normal mice, hypogonadal (hpg) mutants which do not produce detectable hypothalamic LHRH (Cattanach et al., 1977) and testicular feminised (tfm) mutants which do not respond to androgenic negative feedback (Naik et al., 1984). In addition, rats at different stages of the oestrous cycle have been studied to correlate changes in the morphology of gonadotrophs with changes in pituitary responsivness to LHRH. Our results indicate that augmentation of gonadotroph responsiveness to LHRH, such as that which occurs during the priming effect of LHRH involves a reversible migration of secretory granules to the surface of the gonadotrophs and a change in granule dimension indicative of increased intra-granular processing, associated with changes in the length and orientation of cytoskeletal microfilaments.
Keywords
- Luteinizing Hormone
- Marginal Zone
- Luteinizing Hormone Release Hormone
- Luteinizing Hormone Surge
- Oestrous Cycle
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References
Aiyer, M. S., Chiappa, S. A., and Fink, G., 1974a, A priming effect of luteinizing hormone releasing factor on the anterior pituitary-gland of the female rat, J. Endocrinol., 62: 573.
Aiyer, M. S., Fink, G., and Greig, F., 1974b, Changes in the sensitivity of the pituitary gland to luteinizing hormone releasing factor (LRF) during the oestrous cycle of the rat. J. Endocrinol., 60:47
Cattanach, B. M., Iddon, C. A., Charlton, H. M., Chiappa, S. A., and Fink, G., 1977, Gonadotrophin releasing hormone deficiency in a mutant mouse with hypogonadism, Nature, 260:338.
Charlton, H. M., Halpin, D. M. G., Iddon, C., Rosie, R., Levy, G., McDowell, I. F. W., Megson, A., Morris, J. F., Bramwell, A., Speight, A., Ward, B. J., Broadhead, J., Davey-Smith, G., and Fink, G., 1983, The effects of daily administration of single or multiple injections of gonadotropin-releasing hormone on pituitary and gonadal function in the hypogonadal (hpg) mouse, Endocrinology, 113:535.
Childs, G. V., 1985, Shifts in gonadotropin storage following GnRH stimulation in vitro, Peptides, 6:103.
Curtis, A., Lyons, V., and Fink, G., 1985, The priming effect of LH-releasing hormone; effects of cold and involvement of new protein synthesis, J. Endocrinol., 105:163.
Fink, G., 1979, Neuroendocrine regulation of gonadotrophin secretion, Brit. Med. Bull., 35:155.
Fink, G., Chiappa, S. A., and Aiyer, M. S., 1976, Priming effect of luteinizing hormone releasing factor elicited by preoptic stimulation and by intravenous infusion and multiple injections of the synthetic decapeptide, J. Endocrinol., 69:359.
Fink, G., Sheward, W. J., and Charlton, H. M., 1982, Priming effect of luteinizing hormone releasing hormone in the hypogonadal mouse, J. Endocrinol., 94: 283.
Knobil, E., 1980, The neuroendocrine control of the menstrual cycle, Rec. Prog. Horm. Res., 36:53.
deKoning, J., van Dietan, O. A. M. J., and van Rees, G. P., 1976, LHRH dependent release of protein synthesis necessary for LH release from rat pituitary glands in vitro, Mol. Cell Endocrinol., 5:151.
Lewis, C. E., Morris, J. F., and Fink, G., 1985, The role of microfilaments in the priming effect of LH-releasing hormone: an ultrastructural study using cytochalasin B, J. Endocrinol., 106:211.
Lewis, C. E., Morris, J. F., Fink, G., and Johnson, M., 1986, Changes in the granule population of gonadotrophs of hypogonadal (hpg) and normal female mice associated with the priming effect of LH-releasing hormone in vitro. J. Endocrinol., 109: In Press.
Naik, S. I., Young, L. S., Charlton, H. M., and Clayton, R. N., 1984, Pituitary gonadotrophin-releasing hormone receptor regulation in mice II: Females, Endocrinology, 115:114.
Niswender, G. D., Midgley, A. R. Jr., Monroe, S. E., and Reichert, L. E. Jr., 1968, Radioimmunoassay for rat luteinizing hormone with antiovine LH serum and ovine LH-131 I, Proc. Soc. Exp. Biol. Med., 128:807.
Pickering, A. J. M. C., and Fink, G., 1976a, Priming effect of luteinizing hormone releasing factor: in vitro and in vivo evidence consistent with its dependence upon protein and RNA synthesis, J. Endocrinol., 69:373.
Pickering, A. J. M. C., and Fink, G., 1976b, Priming effect of luteinizing hormone releasing factor: in vitro studies with raised potassium concentrations, J. Endocrinol., 69:453.
Pickering, A. J. M. C., and Fink, G., 1979, Priming effect of luteinizing hormone releasing factor in vitro: role of protein synthesis, contractile elements, Ca2+ and cyclic AMP, J. Endocrinol., 81:223.
Polak, J. M., Bloom, S. R., McCrossan, M., Timson, C. M., Arimura, A., and Pearse, A. G. E., 1976, Studies on G cell pathology, Gut 17:400.
Rommler, A., Seinsch, V., Hasan, A. S., and Haase, F., 1978, Ultrastructure of rat pituitary gonadotrophs in relation to serum and pituitary LH levels following repeated LHRH stimulation, Cell Tiss. Res., 190:135.
Tixier-Vidal, A., Gourdji, A. D., and Tougard, C., 1975, A cell culture approach to the study of anterior pituitary cells, Int. Rev. Cytol., 41:173.
Waring, D. W., and Turgeon, J. L., 1980, Luteinizing hormone releasing hormone secretion in vitro: cyclic changes in the responsiveness and self-priming, Endocrinology, 106:1430.
Waring, D. W., and Turgeon, J. L., 1983, Self-priming effect of luteinizing hormone releasing hormone on gonadotrophin secretion, Am. J. Physiol., 244:C410.
Weibel, E. R., 1973, Stereological techniques for electron microscopic morphometry, In: Principles and techniques of electron microscopy. Ed. M. A. Hayat. New York. Van Nostrand Reinhold.
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© 1986 Plenum Press, New York
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Morris, J.F., Lewis, C.E., Fink, G. (1986). LHRH Priming in Gonadotrophs: A Model System for the Analysis of Neuroendocrine Mechanisms at the Cellular Level. In: Fink, G., Harmar, A.J., McKerns, K.W. (eds) Neuroendocrine Molecular Biology. Biochemical Endocrinology. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-5131-3_29
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DOI: https://doi.org/10.1007/978-1-4684-5131-3_29
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