Reversible antagonist

The most convincing data indicate that hallucinogens augment spinal reflexes by stimulating spinal, excitatory (postsynaptic antagonist-reversible) 5-HT receptors, which probably exist on or in close proximity to alpha-motoneurons. 

Data gathered using a few hallucinogens indicate that these agents may depress spinal reflexes by interacting with antagonist-reversible receptors that are located in the dorsal horn of the spinal cord. 

Hallucinogens may interact with tonically active descending 5-HT systems to facilitate reflexes by disinhibition or depress reflexes by reducing tonic facilitation both these influences may be mediated through antagonist-reversible postsynaptic receptors. 

Martin P, Gozlan H, Puech AJ. (1992). 5-HT3 receptor antagonists reverse helpless behaviour in rats. Eur J Pharmacol. 212(1) 73-78. 

Fluoxetine and 5HT1A antagonist Reversed withdrawal-induced increased ICSS thresholds Harrison et al. (2001)... 

Harrison AA, Liem YT, Markou A (2001) Fluoxetine combined with a serotonin-lA receptor antagonist reversed reward deficits observed during nicotine and amphetamine withdrawal in rats. Neuropsychopharmacology 25 55-71... 

Hj-receptor antagonists reversibly and competitively inhibit histamine action on H2 receptors. They are pure antagonists since they do not affect Hj receptors, j3-adrenorecep-tors, or muscarinic receptors. 

Mechanism of Action An antidote to folic acid antagonists that may limit methotrexate action on normal cells by competing with methotrexate for the same transport processes into the cells Therapeutic Effect Reverses toxic effects of folic acid antagonists. Reverses folic acid deficiency. 

Since GABA is the most widespread inhibitory neurotransmitter in the brain [71], its role as hypothetical intermediary in the mechanism of H3 receptor-mediated moderation of ACh release was investigated. Bicuculline, a GABAa receptor antagonist, reversed the inhibition of ACh release induced by immepip, an H3 receptor agonist, in a concentration-dependent fashion (Table 1). 

Mammalian y-aminobutyric addB receptors structure and function. Pharmacol Rev 54 247-64 Brakeman PR, Lanahan AA, O Brien R et al (1997) Homer a protein that selectively binds metabotropic glutamate receptors. Nature 386 284—8 Bremner JD, Krystal JH, Southwick SM, Chamey DS (1996) Noradrenergic mechanisms in stress and anxiety II. Preclinical studies. Synapse 23 28-38 Breysse N, Baunez C, Spooren W et al (2002) Chronic but not acute treatment with a metabotropic glutamate 5 receptor antagonist reverses the akinetic deficits in a rat model of parkinsonism. J Neurosd 22 5669-78... 

King MV, Sleight AJ, Woolley ML, Tophan IA, Marsden CA, Fone KCF. 5-HT6 receptor antagonists reverse delay-dependent deficits in novel object discrimination by enhancing consolidation an effect sensitive to NMDA receptor antagonism. Neuropharmacology 2004 47 195-204. 

Mansbach RS, Brooks EW, Sanner MA, Zorn SH (1998) Selective dopamine D4 receptor antagonists reverse apomorphine-induced blockade of prepulse inhibition. Psychopharmacol 735 194-200. 

Consistent with these findings, 5-HT2A antagonists reverse catalepsy induced by typical antipsychotics such as haloperidol (585). 

Breysse N, Baunez C, Spooren W et al (2002) Chronic but not acute treatment with a metabotropic glutamate 5 receptor antagonist reverses the akinetic deficits in a rat model of parkinsonism. J Neurosci 22 5669-5678... 

Dopamine-j8-hydroxylase (Dj H) inhibitors such as diethyldithiocarbamate (DDC) and l-phenyl-3-(2-thiazoyl)-2-thiourea (PTT) are known to remove copper from this copper-dependent enzyme and, in addition, potentiate antagonist-reversible morphine analgesia [202,203]. Watanabe, Matsui and Iwata [202] were the first to report that DDC elevated pain threshold and potentiated morphine analgesia in the tail-clip and hot-plate pain models. Bhargava and Way [203] subsequently reported that PTT also elevated pain threshold and reversed or prevented morphine tolerance by potentiating analgesia in naive and morphine-tolerant mice and prevented symptoms of abrupt morphine withdrawal and symptoms of naloxone-precipitated withdrawal. 

Ipratropium (Atrovent) Muscarinic antagonist. Reverses acetyichoiine -induced bronchoconstriction. Bronchospasm associated with COPD in aduits. Few systemic anticholinergic side effects because it is a quaternery ammonium compound which crosses into systemic circulation poorly. 

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