Rhythmicity of luteinizing hormone secretion expressed in vitro

1996 ◽  
Vol 135 (4) ◽  
pp. 455-463 ◽  
Author(s):  
Hadas Lewy ◽  
Zvi Naor ◽  
Israel E Ashkenazi
Keyword(s):  
Luteinizing Hormone ◽  
Human Genetics ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone ◽  
Tel Aviv ◽  
Hypothalamic Control ◽  
Lh Release

Lewy H, Naor Z, Ashkenazi IE. Rhythmicity of luteinizing hormone secretion expressed in vitro. Eur J Endocrinol 1996;135:455–63. ISSN 0804–4643 In the present study we explored the possibility that the pituitary functions as an autonomous clock and is capable of generating rhythms of luteinizing hormone (LH) release independently of hypothalamic control. Pituitaries from estrous or diestrous day 1 female mice were perifused separately with Medium-199. Effluent samples were collected at 10-min intervals and assayed for LH levels. Fourier analysis and curve-fit analysis served to elucidate the presence of prominent periods whose significance was then determined by best-fit cosinor. The latter method was used to determine additional parameters for the significant rhythm. All perifused pituitaries exhibited LH release patterns that were composed of significantly long ultradian rhythms (approximately 16 and 8 h, p < 0.001). Continuous stimulation with gonadotropin-releasing hormone (GnRH) or estradiol did not alter the periods of the observed rhythms but affected other rhythm parameters. Gonadotropin-releasing hormone increased the mesor of the rhythm and estradiol increased the amplitude. The results indicate that pituitary gonadotropes are capable of producing rhythms of LH release for a long duration in vitro, in the absence of hypothalamic control. Both GnRH and estradiol affect different rhythm parameters but do not change the periods of these rhythms. Israel E Ashkenazi, Department of Human Genetics, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel

Influence of folliculo-stellate cells on biphasic luteinizing hormone secretion response to gonadotropin-releasing hormone in rat pituitary cell aggregates

1994 ◽  
Vol 130 (5) ◽  
pp. 530-539 ◽  
Author(s):  
Wilfried Allaerts ◽  
Ans MI Tijssen ◽  
Pieter HM Jeucken ◽  
Hemmo A Drexhage ◽  
Jurrien de Koning
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Stellate Cells ◽  
Gonadotropin Releasing Hormone ◽  
Pituitary Cells ◽  
Cell Aggregates ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone ◽  
Biphasic Pattern ◽  
Lh Release

Allaerts W, Tijssen AMI, Jeucken PHM, Drexhage HA, de Koning J. Influence of folliculo-stellate cells on biphasic luteinizing hormone secretion response to gonadotropin-releasing hormone in rat pituitary cell aggregates. Eur J Endocrinol 1994;130:530–9. ISSN 0804–4643 Anterior pituitary cells cultured as three-dimensional cell aggregates and incubated with gonadotropin-releasing hormone (GnRH) show a biphasic pattern of luteinizing hormone (LH) release when steroid-free bovine follicle fluid is added to the culture medium. Initially, the GnRH-induced LH release is low (lag-phase response), but LH release increases during further incubations with GnRH (primed-state response). Also, in aggregates of dispersed cells from long-term ovariectomized rats cultured for 2 days in the presence of 1% bovine follicle fluid, a low initial LH responsiveness to GnRH could be restored. Cycloheximide was found to block the induction of the primed state, indicating the protein synthesis dependency of GnRH self-priming. In aggregates from gonadotroph-enriched cell populations obtained by velocity sedimentation in a bovine serum albumin gradient, addition of 1% bovine follicle fluid to the culture medium also restored a biphasic pattern of GnRH-induced LH release. However, co-culturing the gonadotroph-enriched cell aggregates with a folliculo-stellate (FS) cell-enriched population resulted in the attenuation of the differences in LH secretion rate between early and late responses to GnRH. The present example of the attenuation by folliculo-stellate cells of pituitary hormone secretion responses demonstrates that the cells regulate the cellular processes leading to a priming of the LH response to GnRH, rather than interfering with the access of GnRH to its receptor in gonadotrophs. Finally, it was found that stimulation of the adenylate cyclase enzyme with maximal effective doses of forskolin counteracted the inhibitory effect of bovine follicle fluid on the initial LH response to GnRH, but did not completely abolish the biphasic pattern of LH release. It is concluded that coupling to the adenylate cyclase enzyme is presumably involved in the LH surge inhibiting feedback action on the pituitary cells, but also other messenger pathways and intercellular interactions between pituitary cells may play a role in establishing a biphasic LH release at the pituitary level following GnRH administration. W Allaerts, Dept. of Immunology, Erasmus University Rotterdam, PO Box 1738, 3000 DR Rotterdam, The Netherlands

Regulation of Gonadotropin-Releasing Hormone and Luteinizing Hormone Secretion by AMPA Receptors

1997 ◽  
Vol 66 (4) ◽  
pp. 246-253 ◽  
Author(s):  
Lin Ping ◽  
Virendra B. Mahesh ◽  
Ganapathy K. Bhat ◽  
Darrell W. Brann
Keyword(s):  
Luteinizing Hormone ◽  
Ampa Receptors ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone

scholarly journals Induction of final oocyte maturation in Cyprinidae fish by hypothalamic factors: a review

2009 ◽  
Vol 54 (No. 3) ◽  
pp. 97-110 ◽  
Author(s):  
P. Podhorec ◽  
J. Kouril
Keyword(s):  
Luteinizing Hormone ◽  
Oocyte Maturation ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Gonadotropin Releasing Hormone ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone ◽  
Final Oocyte Maturation ◽  
In Captivity ◽  
Lh Secretion

Gonadotropin-releasing hormone in Cyprinidae as in other Vertebrates functions as a brain signal which stimulates the secretion of luteinizing hormone from the pituitary gland. Two forms of gonadotropin-releasing hormone have been identified in cyprinids, chicken gonadotropin-releasing hormone II and salmon gonadotropin-releasing hormone. Hypohysiotropic functions are fulfilled mainly by salmon gonadotropin-releasing hormone. The only known factor having an inhibitory effect on LH secretion in the family Cyprinidae is dopamine. Most cyprinids reared under controlled conditions exhibit signs of reproductive dysfunction, which is manifested in the failure to undergo final oocyte maturation and ovulation. In captivity a disruption of endogenous gonadotropin-releasing hormone stimulation occurs and sequentially that of luteinizing hormone, which is indispensible for the final phases of gametogenesis. In addition to methods based on the application of exogenous gonadotropins, the usage of a method functioning on the basis of hypothalamic control of final oocyte maturation and ovulation has become popular recently. The replacement of natural gonadotropin-releasing hormones with chemically synthesized gonadotropin-releasing hormone analogues characterized by amino acid substitutions at positions sensitive to enzymatic degradation has resulted in a centuple increase in the effectiveness of luteinizing hormone secretion induction. Combining gonadotropin-releasing hormone analogues with Dopamine inhibitory factors have made it possible to develop an extremely effective agent, which is necessary for the successful artificial reproduction of cyprinids.

Gonadotropin-Releasing Hormone-Stimulated Luteinizing Hormone Secretion by Perifused Pituitary Cells from Normal, Gonadectomized, and Testicular Feminized Rats*

Endocrinology ◽  
1990 ◽  
Vol 126 (6) ◽  
pp. 3022-3027 ◽  
Author(s):  
RICHARD J. KRIEG ◽  
JUDY M. BATSON ◽  
PAUL M. MARTHA ◽  
DENNIS W. MATT ◽  
RONALD L. SALISBURY ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Pituitary Cells ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone

scholarly journals Galanin Enhancement of Gonadotropin-Releasing Hormone-Stimulated Luteinizing Hormone Secretion in Female Rats Is Estrogen Dependent

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 484-490 ◽  
Author(s):  
Cynthia L. Splett ◽  
Joseph R. Scheffen ◽  
Joshua A. Desotelle ◽  
Vicky Plamann ◽  
Angela C. Bauer-Dantoin
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Luteinizing Hormone Secretion ◽  
Ovx Rats ◽  
Lh Secretion ◽  
Lines Of Evidence

The hypothalamic peptide GnRH is the primary neuroendocrine signal regulating pituitary LH in females. The neuropeptide galanin is cosecreted with GnRH from hypothalamic neurons, and in vitro studies have demonstrated that galanin can act at the level of the pituitary to directly stimulate LH secretion and also augment GnRH-stimulated LH secretion. Several lines of evidence have suggested that the hypophysiotropic effects of galanin are important for the generation of preovulatory LH surges. To determine whether the pituitary actions of galanin are enhanced by the preovulatory steroidal milieu, LH responses to galanin administration (with or without GnRH) were examined in: 1) ovariectomized (OVX); 2) OVX, estrogen (E)-primed; and 3) OVX, E- and progesterone-treated female rats. Results from the study indicate that galanin enhances GnRH-stimulated LH secretion only in the presence of E (in OVX, E-primed, or E- and progesterone-treated rats). Galanin alone does not directly stimulate LH secretion under any of the steroid conditions examined. In the absence of gonadal steroids (OVX rats), galanin inhibits GnRH-stimulated LH secretion. These findings suggest that the primary pituitary effect of galanin is to modulate GnRH-stimulated LH secretion, and that the potentiating effects of galanin occur only in the presence of E.

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