mdl-100907 and Acute-Disease

Ziprasidone, a benzisothiazolyl piperazine-type atypical antipsychotic agent, has a unique receptor-binding profile. A potent antagonist of serotonin 5-HT(2A) and dopamine D(2) receptors, ziprasidone has an affinity for 5-HT(2A) receptors >10-fold higher than its affinity for D(2) receptors. Ziprasidone has been shown to be effective in the treatment of bipolar disorder in patients experiencing manic or mixed episodes. It was significantly more effective than placebo in improving manic symptoms as early as day 2 of treatment in two 3-week placebo-controlled trials as monotherapy. In a 12-week, placebo-controlled trial of patients with acute mania, ziprasidone as monotherapy showed comparable efficacy with, and fewer movement-related adverse events than, haloperidol. It has demonstrated efficacy in two 1-year open-label extension trials, both as monotherapy and in combination with lithium. Ziprasidone has a generally favourable adverse effect profile. In short-term placebo-controlled trials, there were similar discontinuation rates in active treatment and placebo recipients. While twice as many patients treated with ziprasidone compared with placebo discontinued therapy because of adverse events, the number of events was small and adverse effects were generally mild or moderate. The favourable tolerability of ziprasidone has been confirmed in long-term extension studies and its use was not associated with weight gain or dyslipidaemia. Ziprasidone-related movement disorders occurred infrequently.

Topics: Acute Disease; Administration, Oral; Antipsychotic Agents; Bipolar Disorder; Dopamine D2 Receptor Antagonists; Humans; Piperazines; Serotonin 5-HT2 Receptor Antagonists; Thiazoles; Treatment Outcome

Acute intermittent hypoxia (AIH) induces phrenic long-term facilitation (pLTF) by a mechanism that requires spinal serotonin (5-HT) receptor activation and NADPH oxidase (NOX) activity. Here, we investigated whether: (1) spinal nitric oxide synthase (NOS) activity is necessary for AIH-induced pLTF; (2) episodic exogenous nitric oxide (NO) is sufficient to elicit phrenic motor facilitation (pMF) without AIH (i.e. pharmacologically); and (3) NO-induced pMF requires spinal 5-HT2B receptor and NOX activation. In anesthetized, mechanically ventilated adult male rats, AIH (3 × 5-min episodes; 10% O2; 5 min) elicited a progressive increase in the amplitude of integrated phrenic nerve bursts (i.e. pLTF), which lasted 60 min post-AIH (45.1 ± 8.6% baseline). Pre-treatment with intrathecal (i.t.) injections of a neuronal NOS inhibitor (nNOS-inhibitor-1) near the phrenic motor nucleus attenuated pLTF (14.7 ± 2.5%), whereas an inducible NOS (iNOS) inhibitor (1400 W) had no effect (56.3 ± 8.0%). Episodic i.t. injections (3 × 5μl volume; 5 min) of a NO donor (sodium nitroprusside; SNP) elicited pMF similar in time-course and magnitude (40.4 ± 6.0%, 60 min post-injection) to AIH-induced pLTF. SNP-induced pMF was blocked by a 5-HT2B receptor antagonist (SB206553), a superoxide dismutase mimetic (MnTMPyP), and two NOX inhibitors (apocynin and DPI). Neither pLTF nor pMF was affected by pre-treatment with a protein kinase G (PKG) inhibitor (KT-5823). Thus, spinal nNOS activity is necessary for AIH-induced pLTF, and episodic spinal NO is sufficient to elicit pMF by a mechanism that requires 5-HT2B receptor activation and NOX-derived ROS formation, which indicates AIH (and NO) elicits spinal respiratory plasticity by a nitrergic-serotonergic mechanism.

Topics: Acute Disease; Animals; Cyclic GMP-Dependent Protein Kinases; Enzyme Inhibitors; Hypoxia; Male; NADPH Oxidases; Neuronal Plasticity; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type I; Phrenic Nerve; Rats; Reactive Oxygen Species; Receptor, Serotonin, 5-HT2B; Serotonin 5-HT2 Receptor Antagonists; Spinal Cord; Superoxide Dismutase

Acute intermittent hypoxia [AIH; 3, 5-min episodes; 35-45 mmHg arterial PO(2) (Pa(O(2)))] elicits serotonin-dependent phrenic long-term facilitation (pLTF), a form of phrenic motor facilitation (pMF) initiated by G(q) protein-coupled metabotropic 5-HT(2) receptors. An alternate pathway to pMF is induced by G(s) protein-coupled metabotropic receptors, including adenosine A(2A) receptors. AIH-induced pLTF is dominated by the serotonin-dependent pathway and is actually restrained via inhibition from the adenosine-dependent pathway. Here, we hypothesized that severe AIH shifts pLTF from a serotonin-dependent to an adenosine-dependent form of pMF. pLTF induced by severe (25-30 mmHg Pa(O(2))) and moderate (45-55 mmHg Pa(O(2))) AIH were compared in anesthetized rats, with and without intrathecal (C4) spinal A(2A) (MSX-3, 130 ng/kg, 12 μl) or 5-HT receptor antagonist (methysergide, 300 μg/kg, 15 μl) injections. During severe, but not moderate AIH, progressive augmentation of the phrenic response during hypoxic episodes was observed. Severe AIH (78% ± 8% 90 min post-AIH, n = 6) elicited greater pLTF vs. moderate AIH (41% ± 12%, n = 8; P < 0.05). MSX-3 (28% ± 6%; n = 6; P < 0.05) attenuated pLTF following severe AIH, but enhanced pLTF following moderate AIH (86% ± 26%; n = 8; P < 0.05). Methysergide abolished pLTF after moderate AIH (12% ± 5%; n = 6; P = 0.035), but had no effect after severe AIH (66 ± 13%; n = 5; P > 0.05). Thus severe AIH shifts pLTF from a serotonin-dependent to an adenosine-dependent mechanism; the adenosinergic pathway inhibits the serotonergic pathway following moderate AIH. Here we demonstrate a novel adenosine-dependent pathway to pLTF following severe AIH. Shifts in the mechanisms of respiratory plasticity provide the ventilatory control system greater flexibility as challenges that differ in severity are confronted.

Topics: Acute Disease; Adenosine; Adenosine A2 Receptor Antagonists; Animals; Blood Pressure; Carbon Dioxide; Disease Models, Animal; Hypoxia; Injections, Spinal; Lung; Male; Neuronal Plasticity; Oxygen; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Receptor, Adenosine A2A; Receptors, Serotonin, 5-HT2; Respiration; Serotonin; Serotonin 5-HT2 Receptor Antagonists; Severity of Illness Index; Time Factors

Akathisia remains one of the most prevalent and distressful antipsychotic-induced adverse events. Effective and well-tolerated treatment is a major unmet need in akathisia that merits a search for new remedies. Accumulating evidence indicates that agents with marked serotonin-2A receptor antagonism may represent a new class of potential anti-akathisia treatment.

Topics: Acute Disease; Akathisia, Drug-Induced; Antipsychotic Agents; Humans; Mianserin; Mirtazapine; Practice Guidelines as Topic; Serotonin 5-HT2 Receptor Antagonists

The effects of R-102444 ((2R, 4R)-4-lauroyloxy-2-[2-[2-[2-(3-methoxy)phenyl]ethyl]phenoxy]ethyl-1-methylpyrrolidine hydrochloride) and its active metabolite R-96544 ((2R, 4R)-2-[2-[2-[2-(3-methoxy)phenyl]ethyl]phenoxy]ethyl-4-hydroxy-1-methylpyrrolidine hydrochloride), potent and selective 5-hydroxytryptamine 2A (5-HT2A) receptor antagonists, on development of pancreatitis were investigated in experimental models of acute and chronic pancreatitis. Rat acute pancreatitis was induced by caerulein (20 microg/kg) intraperitoneal injection and by pancreatic duct ligation. In both the models, serum amylase and lipase activities were markedly increased. R-102444 dose-dependently reduced these enzyme activities at a dose range of 10 to 100 mg/kg (p.o.) for the caerulein model and 0.3 to 10 mg/kg (p.o.) for the ligation model. In a mouse model of acute pancreatitis induced by a choline-deficient, ethionine (0.5%)-supplemented diet, subcutaneous administration of R-96544 (10-100 mg/kg, bid) reduced serum amylase activity. Histological analysis showed that R-96544 dose-dependently attenuated pancreatic necrosis, inflammation and vacuolization. The effect of R-102444 was further examined in male Wistar Bonn/Kobori rats (4-9 months of age) which spontaneously show pancreatic fibrosis and parenchymal destruction compatible with human chronic pancreatitis. In Wistar Bonn/Kobori rats (from 3 to 9 months of age) fed a diet containing 0.017% and 0.17% of R-102444, pancreatic weight, pancreatic protein and amylase content were higher compared to those in non-treated pancreatitis control rats. Histological analysis showed that R-102444 suppressed parenchymal destruction and replacement with adipose tissue, indicating inhibition of pancreatic atrophy. These results clearly indicate that R-102444 and R-96544 inhibit the progression of acute and chronic pancreatitis and support the contention of possible involvement of 5-HT2A receptors in the progression of experimental pancreatitis.

Topics: Acute Disease; Amylases; Animals; Ceruletide; Choline; Chronic Disease; Dietary Supplements; Ethionine; Injections, Intraperitoneal; Ligation; Lipase; Male; Organ Size; Pancreas; Pancreatic Ducts; Pancreatitis; Pyrrolidines; Rats; Rats, Inbred Strains; Rats, Sprague-Dawley; Rats, Wistar; Receptor, Serotonin, 5-HT2A; Serotonin 5-HT2 Receptor Antagonists; Serotonin Antagonists; Time Factors