Search results for "Agoni"
showing 10 items of 2493 documents
Ontogenetic and Pharmacological Studies on Metabotropic Glutamate Receptors Coupled to Phospholipase D Activation
1997
The present study was aimed at characterizing the metabotropic receptor subtype which is involved in the activation of phospholipase D (PLD) by glutamate in rat hippocampal slices. We first observed that the ontogenetic profile of glutamate-induced hydrolysis of phosphoinositides and of phosphatidylcholine was strikingly similar. Both pathways were significantly activated by glutamate in tissue taken from 3-, 8- and 15-day old rats, but not in adult rats. PLD activation was strongest in slices taken from 8-day old rats. At this age, quisqualate had a higher potency for PLD activation (EC50: 0.6 microM) than 1S,3R-ACPD (EC50: 16 microM) and DHPG, a specific activator of group I mGluR, was a …
Progesterone increases basal 3',5'-cyclic adenosine monophosphate formation and down-regulates the agonist-induced inositol phosphates generation in …
1992
Whether the placenta is a target tissue for estrogens and progesterone, and their putative mechanism of action, is still a controversial question in the literature. The effect of progesterone and estradiol on 3′,5′-cyclic adenosine monophosphate (cAMP) and inositol phosphates generation in human term placenta was investigated. Placental explants were incubated in vitro for up to 48 h in the absence and in the presence of estradiol, progesterone or both steroids (0.1 μmol/l final concentration in all cases), and were stimulated with terbutaline, a β-adrenergic agonist, (0.1 mmol/l) or angiotensin II(1 μmol/l), The cAMP content was measured by a competitive protein binding assay, and the gene…
Imidazole derivative KK-42 reduces ecdysteroid titers and interferes with reproductive processes in adult females of Tenebrio molitor
2004
0048-3575 doi: DOI: 10.1016/j.pestbp.2004.07.004; KK-42, an imidazole derivative considered as potent inhibitor of ecdysteroid biosynthesis, was tested on adult females of Tenebrio molitor. The compound was applied topically (0.1, 1, 5, and 10 μg/insect) on 0- or 2-day-old adult females or added to the culture medium (1 and 10 μM) of ovaries. To test the effect of KK-42 on the reproduction capacity, ovaries were explanted from 2- and 4-day-old females corresponding, respectively, to follicles at the beginning and the end of vitellogenesis. KK-42 treatment reduced the fecundity and the longevity of females, and in addition, it delayed oviposition and affected growth and development of oocyte…
Methylprednisolone prevents nerve injury-induced hyperalgesia in neprilysin knockout mice.
2013
The pathophysiology of the complex regional pain syndrome involves enhanced neurogenic inflammation mediated by neuropeptides. Neutral endopeptidase (neprilysin, NEP) is a key enzyme in neuropeptide catabolism. Our previous work revealed that NEP knock out (ko) mice develop more severe hypersensitivity to thermal and mechanical stimuli after chronic constriction injury (CCI) of the sciatic nerve than wild-type (wt) mice. Because treatment with glucocorticoids is effective in early complex regional pain syndrome, we investigated whether methylprednisolone (MP) reduces pain and sciatic nerve neuropeptide content in NEP ko and wt mice with nerve injury. After CCI, NEP ko mice developed more se…
Telmisartan as metabolic modulator: a new perspective in sports doping?
2011
The World Antidoping Agency (WADA) has introduced some changes in the 2012 prohibited list. Among the leading innovations to the rules are that both 5-aminoimidazole-4-carboxamide-1-[beta]-D-ribofuranoside (peroxisome proliferator�activated receptor-[delta] [PPAR-[delta]]-5' adenosine monophosphate-activated protein kinase [AMPK] agonist) and GW1516 (PPAR-[delta]-agonist) are no longer categorized as gene doping substances in the new 2012 prohibited list but as metabolic modulators in the class �Hormone and metabolic modulators.� This may also be valid for the angotensin II receptor blocker telmisartan. It has recently been shown that telmisartan might induce similar biochemical, biological…
Ionotrophic 5-hydroxytryptamine type 3 receptor activates the protein kinase C-dependent phospholipase D pathway in human T-cells
1999
The present study was undertaken to investigate the role of the 5-hydroxytryptamine (5-HT) ionotrophic receptor 5-HT3 in the activation of human Jurkat T-cells. 5-HT and 2-methyl-5-HT (2Me-5-HT), an agonist of the 5-HT3 receptor, induced increases in intracellular free Na+ concentrations, [Na+]i, via opening of the ionotrophic receptor in these cells. These two serotonergic (5-hydroxytryptaminergic) agents potentiated phytohaemagglutinin (PHA)-induced T-cell activation. However, they failed to potentiate dioctanoglycerol-plus-ionomycin-stimulated T-cell blastogenesis. Interestingly, an inhibitor of protein kinase C (PKC), GF 109203X, curtailed significantly 5-HT and 2Me-5-HT-potentiated T-c…
Altered atypical coupling of γ-aminobutyrate type A receptor agonist and convulsant binding sites in subunit-deficient mouse lines
2001
We searched for subunit correlations for GABA(A) receptor-associated atypically GABA-insensitive [35S]TBPS binding. The homomeric beta3 subunit receptors could be excluded, as GABA-insensitive [35S]TBPS binding was present in beta3-/- mice. Localization of GABA-insensitive [35S]TBPS binding correlated best with those of delta, alpha4 and alpha6 subunit mRNAs. The amounts of GABA-insensitive [35S]TBPS binding components were increased in delta-/- mice, but dramatically reduced in alpha6-/- mice, suggesting a role for alpha6 but excluding delta subunits.
Influence of hormonal treatment on the response of the rat isolated uterus to histamine and histamine receptor agonists.
1992
The response of the isolated uterus to histamine and histamine agonists was investigated in progesterone- and oestrogen-treated rats. The uterine inhibitory responses to histamine and 4-methylhistamine (a histamine H2 receptor agonist) were similar in KCl-contracted uteri from progesterone- and oestrogen-treated rats. The histamine H1 receptor agonist, 2-pyridyl-ethylamine, produced a relaxant response only in progesterone dominant uterus. This was inhibited by the histamine H1 receptor antagonist. In the rat isolated uterus which was not preconstricted by KCl, neither histamine, 4-methylhistamine, nor 2-pyridyl-ethylamine produced any effect in the presence or absence of ranitidine. Raniti…
Characterization of sensory neurotransmission and its inhibition via alpha 2B-adrenoceptors and via non-alpha 2-receptors in rabbit iris.
1993
To find out whether, and which type of, adrenoceptors mediate prejunctional inhibition of sensory neurotransmitter release from trigeminal fibres, the modulation of twitch response to electrical field stimulation on rabbit isolated iris was investigated. Evoked iris sphincter contractions consisted of a minor fast cholinergic and a large slow component. The latter was unaffected by atropine and guanethidine, hence nonadrenergic noncholinergic in nature (NANC), but nearly completely abolished by capsaicin pretreatment and by the neurokinin receptor antagonist spantide. The response was probably not mediated by NK2 receptors as SR 48,968, an NK2 selective nonpeptide antagonist, failed to redu…
Galantamine is an allosterically potentiating ligand of neuronal nicotinic but not of muscarinic acetylcholine receptors.
2003
Galantamine (Reminyl), an approved treatment for Alzheimer's disease (AD), is a potent allosteric potentiating ligand (APL) of human alpha 3 beta 4, alpha 4 beta 2, and alpha 6 beta 4 nicotinic receptors (nAChRs), and of the chicken/mouse chimeric alpha 7/5-hydroxytryptamine3 receptor, as was shown by whole-cell patch-clamp studies of human embryonic kidney-293 cells stably expressing a single nAChR subtype. Galantamine potentiates agonist responses of the four nAChR subtypes studied in the same window of concentrations (i.e., 0.1-1 microM), which correlates with the cerebrospinal fluid concentration of the drug at the recommended daily dosage of 16 to 24 mg. At concentrations10 microM, gal…