Long-term activation of protein kinase C by nicotine in bovine adrenal chromaffin cells

• Published in: Journal of neurochemistry Vol. 58; no. 5; p. 1652
• Main Authors: Tuominen, R K, McMillian, M K, Ye, H, Stachowiak, M K, Hudson, P M, Hong, J S
• Format: Journal Article
• Language: English
• Published: England 01-05-1992
• Subjects: Adrenal Glands - cytology; Adrenal Glands - enzymology; Adrenal Glands - metabolism; Animals; Atropine - pharmacology; Cattle; Cells, Cultured; Chlorisondamine - pharmacology; Chromaffin System - cytology; Chromaffin System - enzymology; Chromaffin System - metabolism; Diglycerides - metabolism; Dimethylphenylpiperazinium Iodide - pharmacology; Enzyme Activation - drug effects; Immunoblotting; Nicotine - pharmacology; Phorbol 12,13-Dibutyrate - pharmacology; Protein Kinase C - metabolism; Time Factors
• ISSN: 0022-3042
• DOI: 10.1111/j.1471-4159.1992.tb10037.x

Previous results from our laboratory suggest that long-term treatment of primary cultured bovine adrenal medullary (BAM) chromaffin cells with nicotine or phorbol 12-myristate 13-acetate, either of which directly activates protein kinase C (PKC), increases the mRNA levels encoding catecholamine-synthesizing enzymes and proenkephalin. In the present study, we have examined the effects of nicotine on BAM cell PKC activity with special emphasis on long-term effects. Nicotine increased particulate PKC activity in a concentration-dependent manner when measured using in vitro enzyme assay with histone as the substrate. This effect is mediated through nicotinic cholinergic receptors, because 1,1-dimethylphenylpiperazinium, a nicotinic agonist, had a similar effect. In addition, chlorisondamine, a specific nicotine-receptor blocking drug, antagonized the effect of nicotine. Nicotine also increased specific [3H]phorbol 12,13-dibutyrate ([3H]PdBu) binding within 1 min, the effect of which was maximal between 3 and 12 min. This effect was reversed by chlorisondamine similarly after 12 min and after 18 h of nicotine treatment, indicating that continual nicotinic-receptor occupancy is required for persistent PKC activation. Compared to PKC activation, the onset of nicotine-stimulated diacylglycerol production was slow, and it was observed after 12 min of incubation with nicotine. The diacylglycerol levels, specific [3H]PdBu binding, and PKC activity remained significantly elevated for at least 18 h with continuous nicotine incubation. Furthermore, nicotine increased the PKC immunoreactivity of a particulate protein with a molecular mass of 82 kDa in the western blot. These results suggest that nicotinic-receptor activation increases PKC activity and immunoreactivity in BAM cells.