scholarly journals GnRH Pulse Frequency-Dependent Stimulation of FSHβ Transcription Is Mediated via Activation of PKA and CREB

2013 ◽  
Vol 27 (4) ◽  
pp. 606-618 ◽  
Author(s):  
Iain R. Thompson ◽  
Nick A. Ciccone ◽  
Shuyun Xu ◽  
Sofiya Zaytseva ◽  
Rona S. Carroll ◽  
...  
Keyword(s):  
Pulse Frequency ◽  
Frequency Dependent ◽  
Stimulation Of

scholarly journals Gonadotropin-Releasing Hormone Pulse Frequency-Dependent Activation of Extracellular Signal-Regulated Kinase Pathways in Perifused LβT2 Cells

Endocrinology ◽  
2005 ◽  
Vol 146 (12) ◽  
pp. 5503-5513 ◽  
Author(s):  
Haruhiko Kanasaki ◽  
Gregoy Y. Bedecarrats ◽  
Kyung-Yoon Kam ◽  
Shuyun Xu ◽  
Ursula B. Kaiser
Keyword(s):  
Pulse Frequency ◽  
Frequency Dependent ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Gnrh Release ◽  
The Difference ◽  
Stimulation Of

The pattern of GnRH release is associated with differential synthesis and release of LH and FSH. Using a perifusion system, we previously reported that stimulation of the LβT2 cell line with varying GnRH pulse frequencies resulted in differential stimulation of LHβ and FSHβ gene transcription, analogous to previous observations in primary gonadotropes. In the present study, we investigated the patterns of MAPK activation by GnRH and the role of MAPK in mediating the frequency-dependent effects. In static culture, ERK activation in LβT2 cells stimulated with continuous GnRH (10 nm) was maximal by 10 min and persisted for up to 6 h, with a return to basal levels by 20 h. In contrast, stimulation with continuous GnRH (10 nm) in perifused cells resulted in a more sustained activation of ERK. To investigate the effects of GnRH pulse frequency on ERK activation, perifused LβT2 cells were stimulated with pulsatile GnRH at a frequency of one pulse every 30 min or one pulse every 2 h for 20 h (10 nm, 5 min/pulse). After the final GnRH pulse, cells were lysed at frequent intervals and levels of ERK phosphorylation were measured. Under high-frequency conditions, ERK activation was maximal 10 min after the GnRH pulse and returned to baseline levels by 20 min. In contrast, under lower GnRH pulse frequency conditions, ERK activation occurred more rapidly and activation was more sustained, with a slower rate of ERK dephosphorylation. These changes resulted in different levels of nuclear phosphorylated ERK. Blockade of ERK activation abolished GnRH-dependent activation of LHβ and FSHβ transcription at both high and low pulse frequencies. These results demonstrate that in perifused LβT2 cells, distinct patterns of ERK activation/inactivation are regulated by GnRH pulse frequency, and the difference in ERK activation may be important for GnRH pulse frequency-dependent differential stimulation of LHβ and FSHβ gene expression.

Frequency dependent myocardial potassium fluxes during   adrenergic stimulation of intact pig hearts

1991 ◽  
Vol 25 (5) ◽  
pp. 364-370 ◽  
Author(s):  
O. Ellingsen ◽  
O. M Sejersted ◽  
O. A Vengen ◽  
A. Ilebekk
Keyword(s):  
Adrenergic Stimulation ◽  
Frequency Dependent ◽  
Stimulation Of

Control of mouth opening and pharynx protrusion during feeding in the sea anemone Calliactis parasitica

1975 ◽  
Vol 63 (3) ◽  
pp. 615-626
Author(s):  
I. D. McFarlane
Keyword(s):  
Amino Acids ◽  
Electrical Stimulation ◽  
Reduced Glutathione ◽  
Mouth Opening ◽  
Pulse Frequency ◽  
Sea Anemone ◽  
Conducting System ◽  
Nerve Net ◽  
Calliactis Parasitica ◽  
Stimulation Of

1. Activity in all three known conducting systems (the nerve net, SS1, and SS2) may accompany feeding in Calliactis. The most marked response is an increase in pulse frequency in the SS2 (the endodermal slow conducting system) during mouth opening and pharynx protrusion. 2. Electrical stimulation of the SS2 at a frequency of one shock every 5 s elicits mouth opening and pharynx protrusion in the absence of food. 3. A rise in SS2 pulse frequency is also evoked by food extracts, some amino acids, and in particular by the tripeptide reduced glutathione, which produces a response at a concentration of 10(−5) M. 4. Although the SS2 is an endodermal system, the receptors involved in the response to food appear to be ectodermal. 5. The epithelium that lines the pharynx conducts SS1 pulses, but there is some evidence for polarization of conduction.

Responses of medullary raphe neurons to electrical and chemical activation of vagal afferent nerve fibers

1993 ◽  
Vol 70 (5) ◽  
pp. 1950-1961 ◽  
Author(s):  
A. R. Evans ◽  
R. W. Blair
Keyword(s):  
Electrical Stimulation ◽  
Chemical Activation ◽  
Vagal Afferents ◽  
Frequency Dependent ◽  
Afferent Fibers ◽  
Vagal Afferent ◽  
Mixed Responses ◽  
Excitatory Responses ◽  
Dose Dependent ◽  
Stimulation Of

1. Various intensities, frequencies, and pulse widths of electrical stimulation of vagal afferent fibers were used to assess the responses of 87 medullary raphe neurons to vagal afferent fiber input in pentobarbital sodium-anesthetized, barodenervated paralyzed cats. Thirty-seven neurons were antidromically activated from the T2-T3 segments of the thoracic spinal cord, and 40 neurons could not be antidromically activated. Neurons were located in the nucleus raphe magnus (79%) and the nucleus raphe obscurus (15%). The remaining 6% of the neurons were not found; however, their locations were comparable in depth and position on the midline with other neurons in the same animals whose locations were identified. 2. The responses of 60 neurons to electrical stimulation of vagal afferent fibers were classified as excitatory (38%), inhibitory (24%), or mixed, (7%). The mixed responses were characterized by excitation at one frequency or intensity and inhibition at another frequency or intensity. The remaining 27 neurons did not clearly respond. 3. The excitatory responses to electrical stimulation of the cervical vagus nerve were intensity and frequency dependent. Inhibitory responses were frequency dependent at lower frequencies of stimulation and both frequency and intensity dependent at higher frequencies. The mixed responses were frequency dependent. Overall, longer pulse widths produced significantly greater responses than shorter pulse widths. 4. Thirty-three neurons were tested for responses to chemical stimulation of vagal afferents with intra-atrial injections of three doses of veratridine. Twenty-one percent were excited, 55% were inhibited, and 6% had mixed responses. For the mixed responses, excitation occurred at one dose and inhibition at another. The remaining 18% of the neurons were unresponsive to veratridine. The excitatory responses were dose dependent, but the inhibitory responses were not. Three doses of phenybiguanide (PBG) were also used to chemically activate vagal afferents in 27 neurons. Eleven percent were excited, 44% were inhibited, and 4% had mixed responses. The remaining 41% were unresponsive to PBG. The excitatory and inhibitory responses were dose dependent. 5. When comparing responses in projection and nonprojection neurons, inhibition was seen significantly more often in projection neurons and excitation in nonprojection neurons. Sixty-three percent of the neurons inhibited by electrical stimulation were raphespinal neurons, and 78% of the neurons excited by vagal stimulation were nonprojection neurons. Similar observations were made with the responses to chemical activation of the vagus. 6. Neurons with lower spontaneous discharge rates were more often excited by vagal stimulation and neurons with higher rates were more often inhibited.(ABSTRACT TRUNCATED AT 400 WORDS)

Premature responding following bilateral stimulation of the rat subthalamic nucleus is amplitude and frequency dependent

2004 ◽  
Vol 1008 (2) ◽  
pp. 198-204 ◽  
Author(s):  
Lieve Desbonnet ◽  
Yasin Temel ◽  
Veerle Visser-Vandewalle ◽  
Arjan Blokland ◽  
Veronique Hornikx ◽  
...  
Keyword(s):  
Subthalamic Nucleus ◽  
Bilateral Stimulation ◽  
Frequency Dependent ◽  
Stimulation Of

scholarly journals Frequency-Dependent Electrical Stimulation of the Visual Cortex

2008 ◽  
Vol 18 (23) ◽  
pp. 1839-1843 ◽  
Author(s):  
Ryota Kanai ◽  
Leila Chaieb ◽  
Andrea Antal ◽  
Vincent Walsh ◽  
Walter Paulus
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Frequency Dependent ◽  
Stimulation Of
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