pitolisant and ciproxifan

Autism spectrum disorders (ASDs) are a group of neurodevelopmental conditions defined by behavioral deficits in social communication and interactions, mental inflexibility and repetitive behaviors. Converging evidence from observational and preclinical studies suggest that excessive repetitive behaviors in people with ASD may be due to elevated histaminergic H3 receptor signaling in the striatum. We hypothesized that systemic administration of pharmacological histamine H3 receptor antagonists would attenuate the expression of repetitive behaviors in the BTBR T+Itpr3tf/J (BTBR) mouse inbred strain, an established mouse model presenting autism-like repetitive behaviors and novelty-induced hyperactivity. We further aimed to investigate whether agonism of the histamine H3 receptor would be sufficient to induce repetitive behaviors in the C57BL/6J control mouse strain.. Different doses of H3 receptor agonists (i.e., (R)-α-methylhistamine and immethridine) and H3 receptor antagonists/inverse agonists (i.e., ciproxifan and pitolisant) were administered via intraperitoneal (i.p.) injection in male mice to characterize the acute effects of these compounds on ASD-related behavioral readouts.. The highly selective H3 receptor agonist immethridine significantly increased the time spent in stereotypic patterns in C57BL/6J mice, but this effect appeared to be driven by general sedative properties of the compound. High doses of pitolisant significantly decreased locomotor hyperactivity in novel environments in BTBR mice, without significant effects on repetitive behaviors.. Based on our findings, we conclude that acute H3 receptor manipulation mainly affected general motor activity levels in novel environments. Small changes in stereotyped behaviors were observed but appeared to be driven by altered general activity levels.

Topics: Animals; Autism Spectrum Disorder; Behavior, Animal; Corpus Striatum; Disease Models, Animal; Grooming; Histamine Agonists; Histamine H3 Antagonists; Humans; Hyperkinesis; Imidazoles; Locomotion; Male; Mice; Mice, Inbred C57BL; Piperidines; Receptors, Histamine H3; Social Behavior; Stereotyped Behavior

A series of 4-pyridylpiperazine derivatives with varying regulatory region substituents proved to be potent histamine H

Topics: Animals; Anti-Obesity Agents; Body Weight; Dose-Response Relationship, Drug; Female; Histamine H3 Antagonists; Humans; Imidazoles; Ligands; Models, Molecular; Piperazine; Piperidines; Protein Binding; Rats, Wistar; Receptors, Histamine H3; Regulatory Sequences, Nucleic Acid; Structure-Activity Relationship

Pitolisant (BF2.649) is a selective inverse agonist for the histamine H(3) receptor and was developed for the treatment of excessive daytime sleepiness in Parkinson disease, narcolepsy, and schizophrenia. Since H(3)-ligands can decrease inflammatory pain, we tested Pitolisant in inflammatory and neuropathic pain models. MATERIALS AND TREATMENTS: Behavioral effects of pitolisant and the structural different H(3) receptor inverse agonists ciproxifan and ST-889 were tested in zymosan-induced inflammation and the spared nerve injury model for neuropathic pain.. Responses to mechanical and thermal stimuli were determined. Calcium imaging was performed with primary neuronal cultures of dorsal root ganglions.. Clinically relevant doses of pitolisant (10 mg/kg) had no relevant effect on mechanical or thermal pain thresholds in all animal models. Higher doses (50 mg/kg) dramatically increased thermal but not mechanical pain thresholds. Neither ciproxifan nor ST-889 altered thermal pain thresholds. In peripheral sensory neurons high concentrations of pitolisant (30-500 μM), but not ciproxifan, partially inhibited calcium increases induced by capsaicin, a selective activator of transient receptor potential vanilloid receptor 1 (TRPV1). High doses of pitolisant induced a strong hypothermia.. The data show a dramatic effect of high dosages of pitolisant on the thermosensory system, which appears to be H(3) receptor-independent.

Topics: Animals; Behavior, Animal; Calcium; Cells, Cultured; Ganglia, Spinal; Histamine Agonists; Histamine H3 Antagonists; Hot Temperature; Hypothermia; Imidazoles; Mice; Pain; Pain Threshold; Piperidines; Psychomotor Performance

H(3)-receptor inverse agonists raise a great interest as innovative therapeutics in several central disorders. Whereas their procognitive properties are well established, their antipsychotic-like properties are still debated.. We further explored the effect of maximal doses (3-10 mg/kg) of ciproxifan, BF2.649, and ABT-239, three selective H(3)-receptor inverse agonists, on deficits of prepulse inhibition (PPI) induced by apomorphine, MK-801, and phencyclidine (PCP). Their effect was also investigated on stereotypies induced by apomorphine and methamphetamine.. Ciproxifan, BF2.649, and ABT-239 did not reverse the PPI impairment produced by apomorphine (0.5 mg/kg, subcutaneous) in rats. Ciproxifan and BF2.649 did not reverse the impairment induced in mice by MK-801 (0.3 mg/kg). Ciproxifan and BF2.649 also failed to reverse the disruption induced in mice by PCP (5-10 mg/kg). Low to moderate doses of haloperidol (0.1-0.4 mg/kg, intraperitoneal), alone or co-administered with BF2.649, did not reverse MK-801-induced PPI disruption. A high dose (1 mg/kg) of haloperidol partially reversed the MK-801-induced deficit and BF2.649 tended to increase this effect, although nonsignificantly. Whereas stereotypies induced in mice by apomorphine and methamphetamine were totally suppressed by haloperidol, the decrease induced by ciproxifan was partial against apomorphine and very low, if any, against methamphetamine.. Their total absence of effect in several validated animal models of the disease does not support antipsychotic properties of H(3)-receptor inverse agonists. However, their positive effects previously reported in behavioral tasks addressing learning, attention, and memory maintain the interest of H(3)-receptor inverse agonists for the treatment of cognitive symptoms of schizophrenia as adjunctive medications.

Topics: Animals; Antipsychotic Agents; Apomorphine; Benzofurans; Dizocilpine Maleate; Drug Inverse Agonism; Haloperidol; Histamine Antagonists; Imidazoles; Inhibition, Psychological; Male; Methamphetamine; Mice; Phencyclidine; Piperidines; Pyrrolidines; Rats; Rats, Sprague-Dawley; Reflex, Startle; Stereotyped Behavior