is a potent, selective, brain penetrant, orally active serotonin 5-HT(6) receptor antagonist with cognitive enhancing, anxiolytic and antidepressant properties. It is able to regulate sleep and wakefulness in rodents. In addition it demostrates antinociceptive and antiepileptic potentials.

WAY 267464 dihydrochloride is a potent and selective agonist at the oxytocin receptor (OTR). WAY 267464 has been shown to cross the blood-brain-barrier to a significantly greater extent than exogenously applied oxytocin. WAY 267464 dose-dependently reduced anxiety on the four-plate test and prevented the deficits in prepulse inhibition induced by MK-801 or amphetamine. The ability of WAY 267464 to function as a V1AR antagonist may limit its potential therapeutic use in humans, as it would conceivably prevent the improvements in social behavior and social cognition that may be assumed to arise from a primary OTR agonist action.

MFZ 10-7 is a high affinity negative allosteric modulator at the mGlu5 receptor (Ki = 0.67 nM). MFZ 10-7 demonstrates anxyolitic properties in mouse models. Intraperitoneal administration of MFZ 10-7 inhibited intravenous cocaine self-administration, cocaine-induced reinstatement of drug-seeking behavior and cocaine-associated cue-induced cocaine-seeking behavior in rats.

ANA-12 is a low-molecular weight antagonist of tropomyosin-related kinase B (TrkB), which is the main receptor of neurotrophin brain-derived neurotrophic factor (BDNF). TrkB and BDNF are both the key mediators in the pathophysiology of several mood disorders, including anxiety and depression. ANA-12 showed direct and selective binding to TrkB and inhibited processes downstream of TrkB without altering TrkA and TrkC functions. It was shown, that mice administered ANA-12 demonstrated reduced anxiety- and depression-related behaviors on a variety of tests predictive of anxiolytic and antidepressant properties in humans.

SB-699551 is the first selective serotonin 5A receptor antagonist. SB-699551 showed an anxiolytic-like property in animal model. It demostrated efficacy against schizophrenia-like cognitive deficits and negative symptoms in rats. Blockade of 5-HT5A receptor with SB-699551 appear to be able to impair the consolidation of memory in rodents. In addition, 5-HT-induced spinal antinociception in the capsaicin and acetic acid tests was blocked by SB-699551.

MCOPPB trihydrochloride (MCOPPB) is a nonpeptide agonist of the NOP receptor, an anxiolytic agent. MCOPPB has a high affinity for the human NOP receptor (pKi = 10.07 +/- 0.01) and selectivity for the NOP receptor over other members of the opioid receptor family: 12-, 270- and >1000-fold more selective for the NOP receptor than for the micro-, kappa-, and delta-receptor, respectively. In an ex vivo binding study, MCOPPB (10 mg/kg, p.o.) inhibited signaling through the NOP receptor in the mouse brain, suggesting that it penetrated into the brain after it was orally administered. MCOPPB - a compound with few adverse effects on the central nervous system - is a potential therapeutic agent for the treatment of anxiety.

CTEP is a compound chemically derived from basimglurant and optimized for utility in rodent studies. CTEP is the first reported mGlu5 inhibitor with both, very long half-life and high oral bioavailability in rodents, classifying as useful pharmacological tool for long-term treatment. CTEP is significantly active in treatment of anxiety in rat and mouse. Chronic treatment with CTEP in a mouse model of Fragile X rescued learning and memory deficits, elevated locomotor activity and increased spine density, suggesting that this treatment may be effective in correcting multiple neurological symptoms. CTEP was able to improve various behavioral alterations induced by chronic social defeat stress.

Sazetidine-A (6-[5-(azetidin-2-ylmethoxy)pyridin-3-yl]hex-5-yn-1-ol or AMOP-H-OH) is a "silent desensitizer" of neuronal nicotinic acetylcholine receptors (nAChRs), meaning that it desensitizes the receptor without first activating it. Later it was shown that Sazetidine-A is an agonist of native and recombinant alpha4beta2 nAChRs but shows differential efficacy on alpha4beta2 nAChRs subtypes. In animal models it is able to regulate the gain in body weight, alcohol and nicotine dependence. Sazetidine-A exerts analgesic, antidepressant and anxiolytic properties.

The investigational psychopharmacologic drug candidate CP 615003 (NGD 91-3) is a potent subtype-selective partial agonist at the GABA-A receptor complex. It was designed to be fast acting without causing the sedation, memory impairment, addiction or potentiation of effects of alcohol associated with conventional anti-anxiety medication. Tissue distribution studies conducted during early clinical development of CP 615003 suggested limited brain penetration. In the Phase II clinical study, subjects tested at the high dose of NGD 91-3 showed a trend toward efficacy that did not achieve statistical significance.

Mitragynine is the main active alkaloid constituent of the plant Mitragyna speciosa Korth. Mitragyna speciosa Korth. (M. speciosa), from the Rubiaceae family, is a tropical medicinal plant native to Southeast Asia. In Malaysia, M. speciosa leaves are known as Ketum or Biak, and in Thailand as Kratom. M. speciosa has been historically used in Southeast Asia as a stimulant drug and in its traditional context as a remedy for various symptoms. Pharmacological activities are mainly mediated via opioid receptors as well as neuronal Ca2+ channels, expression of cAMP and CREB protein and via descending monoaminergic system. Mitragynine acted as a partial agonist at mu-opioid receptors, in contrast, at kappa-opioid receptors, mitragynine was a competitive antagonist, similarly, mitragynine acted as an antagonist at delta-mu-opioid receptors, but with very low potency. Experimental studies in animals have now shown that mitragynine has an addictive potential, however, only at higher doses. Human users in countries of frequent use with a traditional context report a rather low daily consumption with only mild side effects. Kratom and mitragynine can be instrumentalized to enhance physical work power and endurance. A major reason for Kratom consumption is its reported efficacy to replace opiates in chronic users. This makes the Kratom plant preparation and also the isolated compound mitragynine interesting options to treat opiate addiction. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule 1 controlled substances.