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12. The effects of adrenergic agonists on intraocular pressure and on adenylyl cyclase activity of ciliary processes in pigmented rabbits
- Creator:
- Čepelík, J., Dědina, M., and Hynie, S.
- Type:
- article, model:article, and TEXT
- Subject:
- adenylyl cyclase, adrenergic agonists, ciliary processes, desensitization, and intraocular pressure
- Language:
- English
- Description:
- The effects of /¿-adrenergic agonists isoprenaline, fenoterol and clenbuterol on the activity of adenylyl cyclase from ciliary processes and on intraocular pressure were examined in pigmented rabbits. Isoprenaline, fenoterol and clenbuterol stimulated adenylyl cyclase activity in vitro, but clenbuterol behaved as a partial agonist. Preincubation of ciliary processes with any of these three drugs led to the heterologous desensitization of adenylyl cyclase to the stimulatory effects of beta-adrenergic agonists or vasoactive intestinal peptide (VIP). This desensitization was dose-dependent and was expressed mainly as a decrease of the highest effects of stimulatory drugs. The exact mechanism of this phenomenon is not yet known. After topical administration, all three tested /¿-adrenergic agonists decreased intraocular pressure with approximately the same intensity. The relationship between ocular hypotensive effects of /¿-adrenergic agonists and their effects on adenylyl cyclase of ciliary processes is discussed. It is concluded that ocular hypotensive effects of adrenergic agonists and other drugs stimulating adenylyl cyclase cannot be explained simply by stimulation or desensitization of adenylyl cyclase of ciliary processes.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
13. The galanin and galanin receptor subtypes, its regulatory role in the biological and pathological functions
- Creator:
- Šípková, J., Kramáriková, I., Hynie, S., and Klenerová, V.
- Type:
- article, model:article, and TEXT
- Subject:
- galanin, galanin receptor, neurotransmission, galaninergic system, and regulatory function
- Language:
- English
- Description:
- The multitalented neuropeptide galanin was first discovered 30 years ago but initially no biologic activity was found. Further research studies discovered the presence of galanin in the brain and some peripheral tissues, and galanin was identified as a modulator of neurotransmission in the central and peripheral nervous system. Over the last decade there were performed very intensive studies of the neuronal actions and also of nonneuronal actions of galanin. Other galanin family peptides have been described, namely galanin, galanin-like peptide, galanin-message associated peptide and alarin. The effect of these peptides is mediated through three galanin receptors subtypes, GalR1, GalR2 and GalR3 belonging to G protein coupled receptors, and signaling via multiple transduction pathways, including inhibition of cyclic AMP/protein kinase A (GalR1, GalR3) and stimulation of phospholipase C (GalR2). This also explains why one specific molecule of galanin can be responsible for different roles in different tissues. The present review summarizes the information currently available on the relationship between the galaninergic system and known pathological states. The research of novel galanin receptor specific agonists and antagonists is also very promising for its future role in pharmacological treatment. The galaninergic system is important target for current and future biomedical research.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public