The secretion of prolactin, a hormone that acts on the reproductive and immune systems, is regulated synergistically by dopamine and thyrotropin- releasing hormone (TRH). TRH and dopamine are known to affect tyrosine- and/or serine-threonine kinases, release of intracellular Ca2+, and electrical activity. However, the contribution of each of these actions to the control of prolactin secretion is unclear. Therefore, we have been using membrane capacitance measurements to follow exocytosis from single perforated patch clamped lactotrophs. Our results indicate that secretion is steeply dependent on Ca2+ influx. In addition, we have detected novel effects of TRH and dopamine on action potential activity. Furthermore, we have obtained evidence that protein phosphorylation might affect basal as well as stimulated secretion by maintaining and modulating voltage-gated Ca2+ channel activity. Finally, we have found that TRH acts in three phases to promote secretion under voltage clamp conditions. The multiple temporally distinct effects of TRH may be crucial for producing complex patterns of secretion that can be interactively controlled by dopamine. By combining membrane capacitance recordings with microfluorimetric detection of intracellular Ca2+, we propose to determine the roles of regulating action potential activity, voltage-gated Ca2+ channels, intracellular Ca2+ release and buffering, and the secretory apparatus in TRH-induced secretion. We will then determine if protein kinases and phosphatases are essential for TRH action. These studies will form the basis of further investigations on the mechanisms employed by dopamine to control basal and TRH-induced secretion. The proposed experiments will reveal how multiple modulators that activate distinct signal transduction mechanisms interact to control lactotroph secretory activity. It is likely that similar mechanisms will be utilized for coordinated regulation of peptide secretion by other endocrine cells and neurons.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS032385-03
Application #
2445805
Study Section
Endocrinology Study Section (END)
Program Officer
Kitt, Cheryl A
Project Start
1995-08-04
Project End
1999-06-30
Budget Start
1997-07-01
Budget End
1999-06-30
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Pharmacology
Type
Schools of Medicine
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Bulgari, Dinara; Jha, Anupma; Deitcher, David L et al. (2018) Myopic (HD-PTP, PTPN23) selectively regulates synaptic neuropeptide release. Proc Natl Acad Sci U S A 115:1617-1622
Bulgari, Dinara; Deitcher, David L; Levitan, Edwin S (2017) Loss of Huntingtin stimulates capture of retrograde dense-core vesicles to increase synaptic neuropeptide stores. Eur J Cell Biol 96:402-406
Tao, Juan; Bulgari, Dinara; Deitcher, David L et al. (2017) Limited distal organelles and synaptic function in extensive monoaminergic innervation. J Cell Sci 130:2520-2529
Rao, Kavitha; Stone, Michelle C; Weiner, Alexis T et al. (2016) Spastin, atlastin, and ER relocalization are involved in axon but not dendrite regeneration. Mol Biol Cell 27:3245-3256
Cavolo, Samantha L; Bulgari, Dinara; Deitcher, David L et al. (2016) Activity Induces Fmr1-Sensitive Synaptic Capture of Anterograde Circulating Neuropeptide Vesicles. J Neurosci 36:11781-11787
Roland, Bartholomew P; Zeccola, Alison M; Larsen, Samantha B et al. (2016) Structural and Genetic Studies Demonstrate Neurologic Dysfunction in Triosephosphate Isomerase Deficiency Is Associated with Impaired Synaptic Vesicle Dynamics. PLoS Genet 12:e1005941
Cavolo, Samantha L; Zhou, Chaoming; Ketcham, Stephanie A et al. (2015) Mycalolide B dissociates dynactin and abolishes retrograde axonal transport of dense-core vesicles. Mol Biol Cell 26:2664-72
Wong, Man Yan; Cavolo, Samantha L; Levitan, Edwin S (2015) Synaptic neuropeptide release by dynamin-dependent partial release from circulating vesicles. Mol Biol Cell 26:2466-74
Li, Long; Tian, Xiaolin; Zhu, Mingwei et al. (2014) Drosophila Syd-1, liprin-?, and protein phosphatase 2A B' subunit Wrd function in a linear pathway to prevent ectopic accumulation of synaptic materials in distal axons. J Neurosci 34:8474-87
James, Rebecca E; Hoover, Kendall M; Bulgari, Dinara et al. (2014) Crimpy enables discrimination of presynaptic and postsynaptic pools of a BMP at the Drosophila neuromuscular junction. Dev Cell 31:586-98

Showing the most recent 10 out of 52 publications