Drugs online research references
J Pharmacol Exp Ther. 1992 Oct;263(1):395-403.
The role of adrenergic receptors in the initiation of vomiting and its gastrointestinal motor correlates.
Lang IM, Sarna SK.
Department of Surgery, Medical College of Wisconsin, Milwaukee.
We investigated the role of adrenergic receptors in the mechanisms of initiation of vomiting and its gastrointestinal (GI) motor correlates. The effects of clonidine, UK-14304, St-91, naphazoline, phenylephrine and isoproterenol were examined for their ability to initiate vomiting and its GI motor correlates. Only the alpha-2 adrenoceptor agonists UK-14304, clonidine, St-91 and naphazoline activated vomiting and its GI motor correlates. Tolerance of vomiting, but not its GI motor correlates, readily developed to all alpha-2 adrenergic receptor agonists but St-91. The responses to UK-14304 or clonidine were blocked by idazoxan, yohimbine, clonidine tolerance or high doses of phenoxybenzamine, but not by propranolol or prazosin. The responses to UK-14304 or clonidine were also blocked by fentanyl, 1-(1-naphthyl) piperazine, methysergide, SCH 22390 or scopolamine, but not by haloperidol, sulpiride, domperidone or naloxone. Adrenoceptor antagonists, clonidine tolerance or sympathetic blockade did not block vomiting or its GI motor correlates activated by apomorphine, CuSO4 or cholecystokinin-octapeptide. We concluded that alpha-2 adrenergic receptors of the chemoreceptive trigger zone can initiate vomiting and its GI motor correlates, but these receptors do not mediate vomiting induced by another chemoreceptive trigger zone stimulant, apomorphine, or stimulation of the GI tract using CuSO4. However, 5-hydroxytryptamine-2 serotonergic, muscarinic cholinergic and opiate receptors within the central nervous system participate in controlling emesis activated by alpha-2 adrenergic agonists. Peripheral adrenergic receptors do not mediate the GI motor correlates of vomiting.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1357160&dopt=Abstract
Neuroscience. 1991;40(1):159-67.
Muscarinic cholinergic receptors in the rat caudate-putamen and olfactory tubercle belong predominantly to the m4 class: in situ hybridization and receptor autoradiography evidence.
Vilaro MT, Wiederhold KH, Palacios JM, Mengod G.
Preclinical Research, Sandoz Pharma Ltd, Basel, Switzerland.
In order to establish the nature of the muscarinic cholinergic receptors present in the rat caudate-putamen and olfactory tubercle, we have combined in situ hybridization histochemistry with oligonucleotide probes and receptor autoradiography with N-[3H]methyl scopolamine and several subtype-selective antagonists: hexahydro-sila-difenidol, p-fluoro-hexahydro-sila-difenidol, 4-diphenyl-acetoxy-N-methylpiperidine methbromide, AF-DX 116, pirenzepine and methoctramine. In both brain regions, transcripts for the m4 muscarinic receptor subtype were the most abundant, followed by transcripts for the m1 subtype. m2 and m3 transcripts were much less abundant, whereas m5 mRNA was not detected under the present conditions. The binding profiles obtained in these areas were clearly distinct from those obtained in the CA1 layer of the hippocampus and in the pontine nuclei, regions enriched in M1 and M2 sites, respectively. In contrast, they were good agreement with the characteristics of atypical muscarinic receptors present in cell lines such as NG108-15, which contains mRNA for the m4 subtype, and PC12. The profiles displayed by some of the compounds used in the present study for cloned m4 receptors expressed in mammalian cells also agree with our results in rat caudate-putamen and olfactory tubercule. Taken together, these facts support the existence, in rat caudate-putamen and olfactory tubercle, of a major population of muscarinic cholinergic receptors belonging to the M4 type.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2052149&dopt=Abstract
J Comp Neurol. 1990 Aug 22;298(4):431-42.
Muscarinic cholinergic receptors in the songbird and quail brain: a quantitative autoradiographic study.
Ball GF, Nock B, Wingfield JC, McEwen BS, Balthazart J.
Rockefeller University Field Research Center, Millbrook, New York 12545.
In order to clarify the neuroanatomical basis for postulated muscarinic cholinergic control of a wide array of physiological processes in birds, the distribution of muscarinic cholinergic receptors in the brain of three avian species was investigated by quantitative autoradiography. The species consisted of two passerines (songbirds), the European starling (Sturnus vulgaris) and the song sparrow (Melospiza melodia), and one galliform, the Japanese quail (Coturnix coturnix japonica). [3H]N-methyl scopolamine (NMS), a muscarinic cholinergic antagonist was used as the ligand to label the receptors. Initial experiments demonstrated that the binding of this ligand in the three species is saturable in the nanomolar range and has a high affinity (Kd = +/- 0.6 nM). Displacement experiments revealed that three muscarinic ligands competed in an order of potency characteristic of the mammalian muscarinic receptor (i.e., atropine greater than oxotremorine greater than carbachol) for NMS binding in the avian brain. In all three species, portions of the basal ganglia, such as the parolfactory lobe and the paleostriatum augmentatum, exhibited the highest density of binding. On the other hand, the paleostriatum primitivum, the avian homologue of the mammalian globus pallidus, contained very few binding sites. Other telencephalic sites, such as the ventral and dorsal hyperstriatum, also revealed relatively high receptor density. However, the neostriatum and especially the ectostriatum showed much lower levels. In the hypothalamus, in all three species, specific binding could be observed in the ventromedial nucleus and adjacent areas. The paraventricular nucleus also showed moderate levels of binding density, especially in the two songbird taxa. At a more rostral level, the preoptic area showed low levels of binding. In the quail, the sexually dimorphic nucleus of the preoptic area was clearly outlined in the autoradiograms by the low level of binding sites compared to the surrounding areas. In the two passerine species, nuclei of the song system were identified by either high or low levels of NMS binding. High binding defined area X and the mesencephalic nucleus, intercollicularis (ICo). In contrast, the robust nucleus of the archistriatum and the magnocellular nucleus of the anterior neostriatum showed low levels of binding in comparison with the surrounding tissue. None of these nuclei were visible in the quail autoradiograms except for ICo, which appeared as in the passerines as a heavily labelled area surrounding the lightly labelled nucleus mesencephalicus lateralis pars dorsalis. In all three species, the hippocampal complex was devoid of NMS binding except for two lateral dark bands that were present along the entire rostral to caudal extent of the hippocampus.(ABSTRACT TRUNCATED AT 400 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2229474&dopt=Abstract
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