Nonclassical mechanisms of progesterone action in the brain: I. Protein kinase C activation in the hypothalamus of female rats.
The modulation of gene regulation by progesterone (P) and its classical intracellular regulation by progestin receptors in the brain, resulting in alterations in physiology and behavior has been well studied. The mechanisms mediating the short latency effects of P are less well understood. Recent studies have revealed rapid nonclassical signaling action of P involving the activation of intracellular signaling pathways. We explored the involvement of protein kinase C (PKC) in P-induced rapid signaling in the ventromedial nucleus of the hypothalamus (VMN) and preoptic area (POA) of the rat brain. Both the Ca2+-independent (basal) PKC activity representing the activation of PKC by the in vivo treatments and the Ca+2-dependent (total) PKC activity assayed in the presence of exogenous cofactors in vitro were determined. A comparison of the two activities demonstrated the strength and temporal status of PKC regulation by steroid hormones in vivo. P treatment resulted in a rapid increase in basal PKC activity in the VMN but not the POA. Estradiol benzoate priming augmented P-initiated increase in PKC basal activity in both the VMN and POA. These increases were inhibited by intracerebroventricular administration of a PKC inhibitor administered 30 min prior to P. The total PKC activity remained unchanged demonstrating maximal PKC activation within 30 min in the VMN. In contrast, P regulation in the POA significantly attenuated total PKC activity +/- estradiol benzoate priming. These rapid changes in P-initiated PKC activity were not due to changes in PKC protein levels or phosphorylation status.
Balasubramanian
Bhuvana
B
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.
Portillo
Wendy
W
Reyna
Andrea
A
Chen
Jian Zhong
JZ
Moore
Anthony N
AN
Dash
Pramod K
PK
Mani
Shaila K
SK
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D007031:Hypothalamus / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D010052:Ovariectomy; D010766:Phosphorylation / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects / Q000201:enzymology; D011374:Progesterone / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
D007211:Indoles; D008301:Maleimides; D047428:Protein Kinase Inhibitors; D011374:Progesterone; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; C070515:bisindolylmaleimide I; D002118:Calcium