Dopamine release via protein kinase C activation in the fish retina.

Abstract

Calcium-dependent phospholipid-sensitive protein kinase [protein kinase C (PKC)] was partially purified from the carp (Cyprinus carpio) retina through DE 52 ion exchange and Cellulofine gel filtration chromatography. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) activated PKC in the nanomolar range. A major 38-kDa protein in the retinal supernatants (105,000 g) was phosphorylated in vitro by PKC during a short period (3 min). Other phosphoproteins also appeared during a further prolonged period (greater than 15 min). Rod-bipolar and dopamine (DA) interplexiform cells in the fish retina were immunoreactive to a monoclonal antibody to PKC (alpha/beta-subtype). The PKC antibody recognized a 78-kDa native PKC enzyme by means of an immunoblotting method. Subsequently, the effects of two kinds of PKC activators were investigated on [3H]DA release from retinal cell fractions containing DA cells that had been preloaded with [3H]DA. A phorbol ester (TPA) induced a calcium- and dose-dependent [3H]DA release during a short period (2 min), with the minimal effective dose being approximately 1 nM. Other phorbols having no tumor-promoting activity, such as 4 beta-phorbol and 4 alpha-phorbol 12,13-didecanoate, were ineffective on [3H]DA release. A synthetic diacylglycerol [1-oleoyl-2-acetylglycerol (OAG)], which is an endogenous PKC activator, was also able to induce a significant release of [3H]DA. Furthermore, TPA was found to release endogenous DA from isolated fish retina by a highly sensitive HPLC with electrochemical detection method. The OAG- or TPA-induced [3H]DA or DA release was completely blocked by inhibitors of PKC, such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) and staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

• Authors: S Kato, S Ishita, K Mawatari, T Matsukawa, K Negishi
• Journal: Journal of neurochemistry (J Neurochem) Vol. 54 Issue 6 Pg. 2082-90 (Jun 1990) ISSN: 0022-3042 [Print] England
• PMID: 2338558 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids
• Diglycerides
• Tritium
• 1-oleoyl-2-acetylglycerol
• Protein Kinase C
• Tetradecanoylphorbol Acetate
• Dopamine

Topics

• Amino Acids (metabolism)
• Animals
• Carps
• Chromatography, High Pressure Liquid
• Diglycerides (pharmacology)
• Dopamine (metabolism)
• Electrochemistry (methods)
• Enzyme Activation
• Immunohistochemistry
• Protein Kinase C (metabolism)
• Retina (enzymology, metabolism)
• Tetradecanoylphorbol Acetate (pharmacology)
• Tritium