Trace amine-associated receptor 1 (TAAR1)

The selective TAAR1 agonist RO5256390 was used in combination with common damage associated molecular patterns (ATP and ADP) to observe the effect of TAAR1 agonism on modulating cytokine secretion and metabolic profiles. In mouse bone-marrow derived macrophages, TAAR1 agonism inhibited TNF secretion following ATP stimulation, which appeared to be downstream of an associated pro-inflammatory shift in metabolic profile and transcriptional regulation of TNF synthesis. In contrast, TAAR1 agonism had no effect on ADP-induced TNF and IL-6 secretion in mouse microglia in either the presence or absence of astrocytes. In summary, we report a novel interaction between TAAR1 and purinergic signaling in peripherally-derived, but not CNS-resident, macrophages. These findings provide the first evidence of trace aminergic and purinergic crosstalk, and support the potential for TAAR1 as a novel therapeutic target in inflammatory disorders. [1]

Compulsive, binge eating of highly palatable food constitutes a core feature of some forms of obesity and eating disorders, as well as of the recently proposed disorder of food addiction. Trace amine-associated receptor 1 (TAAR1) is a highly conserved G-protein-coupled receptor bound by endogenous trace amines. TAAR1 agonists have been shown to reduce multiple behavioral effects of drugs of abuse through their actions on the mesocorticolimbic system. In this study, we hypothesized that TAAR1 may have a role in compulsive, binge-like eating; we tested this hypothesis by assessing the effects of a TAAR1 agonist, RO5256390, in multiple excessive feeding-related behaviors induced by limiting access to a highly palatable diet in rats. Our results show that RO5256390 blocked binge-like eating in rats responding 1 h per day for a highly palatable sugary diet. Consistent with a palatability-selective effect, drug treatment selectively reduced the rate and regularity of palatable food responding, but it did not affect either baseline intake or food restriction-induced overeating of the standard chow diet. Furthermore, RO5256390 fully blocked compulsive-like eating when the palatable diet was offered in an aversive compartment of a light/dark conflict box, and blocked the conditioned rewarding properties of palatable food, as well as palatable food-seeking behavior in a second-order schedule of reinforcement. Drug treatment had no effect on either anxiety-like or depressive-like behavior, and it did not affect control performance in any of the tests. Importantly, rats exposed to palatable food showed decreased TAAR1 levels in the medial prefrontal cortex (mPFC), and RO5256390 microinfused into the infralimbic, but not prelimbic, subregion of the mPFC-reduced binge-like eating. Altogether, these results provide evidence for TAAR1 agonism as a novel pharmacological treatment for compulsive, binge eating.[2]

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In rodents, activation of TAAR1 by two novel and pharmacologically distinct compounds, the full agonist RO5256390 and the partial agonist RO5263397, blocks psychostimulant-induced hyperactivity and produces a brain activation pattern reminiscent of the antipsychotic drug olanzapine, suggesting antipsychotic-like properties. TAAR1 agonists do not induce catalepsy or weight gain; RO5263397 even reduced haloperidol-induced catalepsy and prevented olanzapine from increasing body weight and fat accumulation. Finally, TAAR1 activation promotes vigilance in rats and shows pro-cognitive and antidepressant-like properties in rodent and primate models. These data suggest that TAAR1 agonists may provide a novel and differentiated treatment of schizophrenia as compared with current medication standards: TAAR1 agonists may improve not only the positive symptoms but also the negative symptoms and cognitive deficits, without causing adverse effects such as motor impairments or weight gain. [3]

The highly selective TAAR1 full agonist RO5256390 (Revel et al, 2012) was synthesized. Doses for Experiment 1 (0, 1, 3, 10 mg/kg) were based on a previously published report (Pei et al, 2014). In the other experiments, the most effective dose from Experiment 1 was used. For intracranial administration, RO5256390 was administered at the doses of 0, 1.5, 5 and 15 μg per side; these doses were chosen based on preliminary observations obtained in our laboratory. For intraperitoneal (i.p.) administration, RO5256390 was freshly dissolved in 0.3% Tween 80 and 0.9% saline; for intracranial administration, RO5256390 was freshly dissolved in a mixture of ethanol:cremophor:saline (2 : 2 : 18 ratio). For within-subject drug testing, 2–4 intervening days were allowed, until subjects' performance returned to baseline conditions. All drug treatments were counterbalanced, unless otherwise specified.[1]

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Experiment 1: effects of the TAAR1 agonist RO5256390 on operant binge-like eating [1]
Rats in the Chow and Palatable food groups (n=12 per group) were administered the TAAR1 agonist RO5256390 (0, 1, 3, 10 mg/kg, i.p.) 30 min prior to the operant sessions.

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High Rate of Responding for Standard Chow Induced by Food Restriction [1]
To reach a higher rate of responding for chow during the operant sessions, rats were food restricted in their home cages for 12 days (to reach a total daily intake equal to 70% of a rat's daily intake; Cottone et al, 2012).

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Experiment 2: effects of the TAAR1 agonist RO5256390 on high rate of responding for standard chow induced by food restriction [1]
Food-restricted rats (n=9 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the operant sessions.

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Experiment 3: effects of the TAAR1 agonist RO5256390 on rate and regularity of sustained eating [1]
Rats in the Chow, food-restricted Chow, and Palatable food groups (n=7–10 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the operant sessions.

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Experiment 4: effects of the TAAR1 agonist RO5256390 on compulsive-like eating [1]
Rats in the Chow and Palatable food groups (n=21–23 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the testing session, using a between-subjects design.
Conditioned Food Reward: Conditioned Place Preference Test [1]
The conditioned place preference (CPP) procedure was performed as previously described (Velazquez-Sanchez et al, 2015).

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Experiment 5: effects of the TAAR1 agonist RO5256390 on conditioned food reward [1]
Rats in the Chow and Palatable food groups (n=16–22 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the post-conditioning phase, using a between-subjects design.

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Experiment 6: effects of the TAAR1 agonist RO5256390 on food-seeking [1]
Rats in the Chow and Palatable food groups (n=6–10 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the second-order sessions.
Anxiety-like Behavior: Defensive Withdrawal Test [1]
For this 10-min test (Cottone et al, 2009; Parylak et al, 2012), rats were placed into a withdrawal chamber (2 l Pyrex beaker wrapped in black tape) within an open field facing the rear. Latency to first emerge (all four paws in the open field) and withdrawal time were used as indices of anxiety-like behavior, although the number of entries into the chamber was used as an index of locomotor activity (Cottone et al, 2009; Parylak et al, 2012).

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Experiment 7: effects of the TAAR1 agonist RO5256390 on anxiety-like behavior [1]
Rats in the Chow and Palatable food groups (n=10–12 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) 30 min prior to the testing session, using a between-subjects design.

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Experiment 8: effects of the TAAR1 agonist RO5256390 on depressive-like behavior [1]
Rats in the Chow and Palatable food groups (n=9–12 per group) were administered the TAAR1 agonist RO5256390 (0, 10 mg/kg, i.p.) at the end of the 15-min pre-test session, and again, 30 min prior to the test, using a between-subjects design.

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Experiments 10–11: effects of microinfusion of the TAAR1 agonist RO5256390 into the IL cortex and PrL cortex on operant binge-like eating [1]
Rats in the Chow and Palatable food groups were microinfused with the TAAR1 agonist RO5256390 (0, 1.5, 5, 15 μg per side) into either the IL (n=8–10 per group) or the PrL (n=11–12 per group) cortex 10 min prior to the operant sessions.

[1]. TAAR1 Regulates Purinergic-induced TNF Secretion from Peripheral, But Not CNS-resident, Macrophages. J Neuroimmune Pharmacol. 2023 Jun;18(1-2):100-111.
[2]. The Trace Amine-Associated Receptor 1 Agonist RO5256390 Blocks Compulsive, Binge-like Eating in Rats. Neuropsychopharmacology. 2017 Jun;42(7):1458-1470.
[3]. A new perspective for schizophrenia: TAAR1 agonists reveal antipsychotic- and antidepressant-like activity, improve cognition and control body weight. Mol Psychiatry. 2013 May;18(5):543-56.

Therefore, here it can be speculated that the effects of TAAR1 agonism on food reward may occur through modulation of the dopaminergic terminals in the mPFC. Palatable food consumption activates the reward circuitry and releases dopamine in the mPFC (Babbs et al, 2013; Volkow et al, 2008). In addition, limited access to palatable food results in neuroadaptations in the reward circuitries, which contribute to compulsive overeating (Volkow et al, 2013). Moreover, obese and binge eating individuals display sensitized responses to conditioned food cues, such as increased prefrontal activation as well as higher dopamine release when exposed to food cues (Dimitropoulos et al, 2012). Hence, the observed effects of TAAR1 activation on food reward may be due to the ability of RO5256390 treatment to restore an impaired prefrontocortical dopaminergic transmission induced by excessive consumption of highly palatable food, although additional studies will be needed to confirm this hypothesis. In summary, our results substantiate the potential for RO5256390 as a pharmacological treatment for disorders characterized by compulsive, binge eating. [2]

C13H20CL2N2O

291.216

218.141

C, 71.53; H, 8.31; N, 12.83; O, 7.33

1043495-96-0

1043495-96-0

24963286

White to off-white solid powder

1.1±0.1 g/cm3

330.9±25.0 °C at 760 mmHg

153.9±23.2 °C

0.0±0.7 mmHg at 25°C

1.576

2.85

1

2

4

16

246

2

CC[C@@H](C[C@H]1COC(=N1)N)C2=CC=CC=C2

NCOOUUDYVQYIDE-HFXMYSAISA-N

InChI=1S/C13H18N2O.2ClH/c1-2-10(11-6-4-3-5-7-11)8-12-9-16-13(14)15-12/h3-7,10,12H,2,8-9H2,1H3,(H2,14,15)2*1H/t10-,12-/m0../s1

(S)-4-((S)-2-phenylbutyl)-4,5-dihydrooxazol-2-amine dihydrochloride

RO5256390; 1043495-96-0; RO5256390; (S)-4-((S)-2-Phenyl-butyl)-4,5-dihydro-oxazol-2-ylamine; TRACE AMINE RECEPTOR 1; (4S)-4-[(2S)-2-phenylbutyl]-4,5-dihydro-1,3-oxazol-2-amine; (S)-4-((S)-2-Phenylbutyl)-4,5-dihydrooxazol-2-amine; IXDKFUBXESWHSL-JQWIXIFHSA-N; SCHEMBL503518; RO-5256390; RO 5256390.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~50 mg/mL (~229.05 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (11.45 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.5 mg/mL (11.45 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (11.45 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)