Electrophysiological Recordings from Gonadotrophs

Mason, William T.; Waring, D. W.

doi:10.1159/000124186

Cited by 49 publications

(7 citation statements)

References 23 publications

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“…Similar voltage-gated channels have been reported to exist in ovine (Mason & Waring, 1985;Mason & Sikdar, 1988) and rat (Stutzin et at. 1989;Marchetti et al 1990) gonadotrophs.…”

Section: Discussionsupporting

confidence: 77%

“…Since Ca2+ influx through the voltagegated channels is modulated by permeability changes of other ionic channels, it is also important to clarify the effects of activin A on ionic channels other than the voltage-gated Ca2+ channels. Although various voltage-gated channels have been reported in ovine (Mason & Waring, 1985;Mason & Sikdar, 1988) and rat gonadotrophs (Stutzin, Stojilkovic, Catt & Rojas, 1989;Marchetti, Childs & Brown, 1990), voltage-gated channels of human FSH-secreting adenoma cells have not yet been investigated. In this study we have investigated various voltage-gated channels in human FSH-secreting adenoma cells, which are suitable for examining the signal transduction mechanism of activin A.…”

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confidence: 99%

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Effects of activin A on ionic channels in human FSH‐secreting tumour cells.

Takano¹,

Ogata²,

Yamashita³

1994

The Journal of Physiology

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1. Effects of activin A on ionic channels were examined in human FSH-secreting tumour cells using electrophysiological techniques. 2. Under voltage clamp with the conventional whole-cell clamp technique, the voltage-gated Na+ channel, the T-and L-type Ca2`channels, the delayed K+ channel and the A-channel were observed. 3. With the nystatin-perforated whole-cell clamp technique, the same voltage-gated channels were recorded. Activin A (10-v M) increased the amplitude of the L-type Ca2" current, whereas it decreased the amplitude of the delayed K+ current. 4. Under current clamp with the perforated whole-cell clamp technique, more than 80 % of the cells exhibited spontaneous action potentials. Application of 10-M activin A depolarized the membrane with a conductance increase and augmented action potential frequency. The reversal potential of the activin A-induced current was -20 to 0 mV. The activin Ainduced current was abolished in a Na+-free extracellular solution, indicating that the membrane depolarization caused by activin A was due to the conductance increase to Na+ ions through non-selective cation channels.

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“…Similar voltage-gated channels have been reported to exist in ovine (Mason & Waring, 1985;Mason & Sikdar, 1988) and rat (Stutzin et at. 1989;Marchetti et al 1990) gonadotrophs.…”

Section: Discussionsupporting

confidence: 77%

mentioning

confidence: 99%

Effects of activin A on ionic channels in human FSH‐secreting tumour cells.

Takano¹,

Ogata²,

Yamashita³

1994

The Journal of Physiology

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“…It (21,22). This channel can be blocked by nifedipine (21,22). Activation of these Ca2"-permeable channels requires the intervention of a diffusible second messenger (22 ester, suggest the possibility that the diffusible second messenger could be diacylglycerol.…”

Section: Methodsmentioning

confidence: 99%

Gonadotropin-releasing hormone-induced Ca2+ transients in single identified gonadotropes require both intracellular Ca2+ mobilization and Ca2+ influx.

Shangold

Murphy

Miller

1988

Proc. Natl. Acad. Sci. U.S.A.

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We examIned the effects of gonadotropinreleasing hormone (GnRH) (10). We now report the use of these techniques to show that GnRH produces Ca2" transients in identified gonadotropes with a very characteristic and complex time course. The role of these transients in the control of gonadotropin release is discussed. MATERIALS AND METHODSCell Culture. Female 35-day-old Sprague-Dawley rats were decapitated, their pituitaries were removed, and adenohypophyses were dissected from neurohypophyses. Anterior pituitaries were then enzymatically dispersed for 20 min with 0.25% trypsin (bovine, type XII-S, Sigma) in a metabolic shaker at 370C. Cells were then filtered through organza cloth (Tetko, Elmsford, NY), diluted to 50 ml in medium 199 with Hanks' salts and L-glutamine (GIBCO), and centrifuged at 350 x g for 10 min. The supernatant was removed, and cells were resuspended by trituration through a Pasteur pipette in 5 ml ofmedium and then were plated on sterile, poly(L-lysine)-coated (10 ,ug/ml, Sigma) etched-grid coverslips (Bellco). The cell density was z'2.5 x 105 cells per coverslip. The cell yield was z4 x 105 cells per rat. Cells were incubated for 2 days in 60-mm Falcon culture dishes, with medium 199 containing 10% (vol/vol) heat-inactivated horse serum (GIBCO) and 2.5% (vol/vol) fetal bovine serum (GIBCO) and supplemented with penicillin (5 units/ml) and streptomycin (50 pg/ml), in a 5% C02/95% air atmosphere in a water-jacketed incubator at 370C.Identification of Isolated Gonadotropes. Sheep erythrocytes (Colorado Serum, Denver) were washed four times in 0.9o NaCl and conjugated to protein A (0.5 mg/ml, Sigma) with CrCl2 (0.2 mg/ml). After further washing, cells were then mixed with LH antiserum (1:5), guinea pig complement (1:10, GIBCO), and GnRH (100 nM, Peninsula Laboratories, San Carlos, CA).

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“…1.8 mM CaCl2, 0.5 mM N; H P04-2H20 , 2.38 g/1 HEPES, 1.8 g/1 glucose, 1 g/1 BSA, pH 7.4) used previously in this laboratory [11] or Medium 199 with Earl's balanced salt solution (Gibco Ltd.. Paisley, UK) which has been used in other perifusion studies [14], The second solution was used in Experiment 3 due to filter-blocking problems encountered with the first solution. Both solutions had I g/1 BSA added and their pH set to 7.4 immediately prior to use.…”

Section: Preparation O F Perifusion Solutionsmentioning

confidence: 99%

Luteinising Hormone Secretion from the Perif used Ovine Pars tuberalis and Pars distalis: Effects of Gonadotropin-Releasing Hormone and Melatonin

Skinner¹,

Robinson²

1997

Neuroendocrinology

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It is not known where melatonin acts to influence the neuroendocrine axis of seasonally breeding mammals. However, since the pars tuberalis (PT) contains the highest density of melatonin receptors, this adenohypophyseal subdivision is a potential target. Gonadotropes are the only immunocytochemically detectable adenohypophyseal cell type of abundance in the PT. This study investigated whether melatonin could modulate basal and/or gonadotropin-releasing hormone (GnRH)-stimulated luteinising hormone (LH) secretion from the ovine PT and pars distalis (PD) in vitro. Tissue fragments from both pituitary areas were placed in separate chambers in a constant-environment perifusion system (37°C; 100 µl/min) and 10-min effluent fractions were collected, frozen and later assayed for LH. Sixty minutes prior to a GnRH challenge (10 min; 10 nM), melatonin (1 µM or 100 nM) was added to the perifusate of half the tissue fragments. GnRH increased (p < 0.01) LH output from both pituitary subdivisions. Melatonin attenuated (p < 0.05) the GnRH-induced increase in LH output from the PT but not from the PD. The physiological importance of this melatonin-attenuated PT LH is unknown but it may play a role in modulating the neuroendocrine reproductive axis.

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Electrophysiological Recordings from Gonadotrophs

Cited by 49 publications

References 23 publications

Effects of activin A on ionic channels in human FSH‐secreting tumour cells.

Effects of activin A on ionic channels in human FSH‐secreting tumour cells.

Gonadotropin-releasing hormone-induced Ca2+ transients in single identified gonadotropes require both intracellular Ca2+ mobilization and Ca2+ influx.

Luteinising Hormone Secretion from the Perif used Ovine Pars tuberalis and Pars distalis: Effects of Gonadotropin-Releasing Hormone and Melatonin

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