Browsing by Subject "yhteisvaikutus"

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channel receptors which are widely distributed in human brain. nAChRs are often expressed pre-synaptically and they modulate the release of other neurotransmitters. nAChRs consist of five subunits: nine different subunits have been identified so far, forming multiple different nAChR subtypes with different pharmacological properties. nAChRs participate extensively in physiological functions and pathophysiological conditions. nAChRs mediate the effects of endogenous agonist, acetylcholine, as well as commonly used substance of abuse, nicotine. Addictive drugs such as nicotine and opioids cause adaptive changes in central nervous system. In addition to binding site of acetylcholine, various allosteric binding sites have been identified in nAChRs. Allosteric ligands are able to modulate the effect of agonist by binding to allosteric binding site. The aim of the experimental part of the pro gradu was to study in vitro interactions of nicotine and three different opioids, codeine, oxycodone and tramadol in SH-SY5Y cells. SH-SY5Y cells express endogenously α3* and α7-nAChRs. Binding assays were performed with radioactive ligand [3H]-epibatidine. Functional interactions of nicotine and the opioids were studied with 86Rb+- efflux assay. Codeine, oxycodone and tramadol exhibited receptor level interactions with nicotine in SH-SY5Y cells. Observed interactions were mediated by nAChRs. The opioids inhibited nAChR activation caused by nicotine without binding to the [3H]-epibatide binding site. Codeine, oxycodone and tramadol appear to affect as weak non-competitive antagonists of nAChRs. These results give further information of nicotine-opioid interactions at receptor level. There are indications that nicotine and opioids also have interactions in vivo, which may be partly explained with these receptor level interactions.