Genetic deletion of β-arrestin 2 modulates LSD-stimulated behaviors in mice

Recent evidence suggests that psychedelic drugs can exert beneficial effects on anxiety, depression, and ethanol and nicotine abuse in humans. However, their hallucinogenic side-effects often preclude their clinical use. Lysergic acid diethylamide (LSD) is a prototypical hallucinogen and its psychedelic actions are exerted through the 5-HT2A serotonin receptor (5-HT2AR). 5-HT2AR activation stimulates Gq- and β-arrestin- (βArr) mediated signaling. To separate these signaling modalities, we have used βArr1 and βArr2 mice. We find that LSD stimulates motor activities to similar extents in WT and βArr1-KO mice, with non-significant effects in βArr2-KOs. LSD robustly stimulates many surrogates of psychedelic drug actions including head twitches, grooming, retrograde walking, and nose-poking in WT and βArr1-KO animals. By contrast, LSD slightly stimulates head twitches in βArr2-KO mice, without effects on other surrogates. The 5-HT2AR antagonist MDL100907 (MDL) blocks these LSD effects. LSD also disrupts prepulse inhibition (PPI) in WT and βArr1-KOs; PPI is unaffected in βArr2-KOs. MDL restores PPI in WT mice, but this antagonist is without effect and haloperidol is required in βArr1-KOs. Collectively, these results reveal that LSD’s psychedelic drug-like actions appear to require βArr2.

LSD’s effects are differentially modulated in arrestin knockout mice

ABSTRACTRecent evidence suggests that psychedelic drugs can exert beneficial effects on anxiety, depression, and ethanol and nicotine abuse in humans. However, the hallucinogenic side-effects of psychedelics often preclude their clinical use. Lysergic acid diethylamide (LSD) is a prototypical hallucinogen and its psychedelic actions are exerted through the 5-HT2A serotonin receptor (5-HT2AR). 5-HT2AR activation stimulates Gq- and β-arrestin-(βArr) mediated signaling. To separate effects of these signaling modes, we have used βArr1 and βArr2 mice. We find that LSD stimulates motor activities to similar extents in WT and βArr1-KO mice, with non-significant effects in βArr2-KOs. LSD robustly stimulates many surrogates of psychedelic drug actions including head twitches, grooming, retrograde walking, and nose poking in WT and βArr1-KO animals. In contrast, LSD only slightly stimulates head twitches in βArr2-KO mice, without effects on retrograde walking or nose poking. The 5-HT2AR antagonist MDL100907 (MDL) blocks these LSD effects. LSD also disrupts prepulse inhibition (PPI) in WT and βArr1-KOs; PPI is unaffected in βArr2-KOs. MDL restores PPI in WT mice, but this antagonist is without effect and haloperidol is required in βArr1-KOs. LSD produces a biphasic body-temperature response in WT mice, a monophasic response in βArr1-KOs, and is without effect in βArr2 mutants. Both MDL and the 5-HT1AR antagonist, WAY 100635 (WAY), block the effects of LSD on body temperatures in WT mice, whereas WAY is effective in βArr1-KOs. Collectively, these results reveal that LSD produces diverse behavioral effects through βArr1 and βArr2, and that LSD’s psychedelic drug-like actions appear to require βArr2.

The effect of short-term lithium treatment on head twitches induced by 5-hydroxytryptophan in mice

The effectiveness of lithium in the treatment of affective disorders is well documented. However, the mechanism of this effect is still unknown. The purpose of this study was to investigate the effect of lithium on serotonergic neurons. The evaluation of the serotoninergic system activity was performed on the basis of an experimental model of head twitch response triggered by direct or indirect stimulation of serotonin 5-HT2 receptors in the brain. The obtained results indicated that the lithium chloride co-applied with a direct precursor of serotonin - 5-hydroxytryptophan used in a threshold dose and with carbidopa, generated head twitch response in mice. What is more, an enhancement of head twitch response in mice was observed after repeated 5-hydroxytryptophan application in head twitch-evoking doses. Moreover, inhibition of the serotonine storage in nerve endings in mice was evoked by reserpine administration. Furthermore, lithium increased the effect of 5-hydroxytryptophan given in a threshold dose and a head twitchevoking dose, respectively. In addition, when P-chlorphenylalanine (pCPA), an inhibitor of the serotonin synthesis within the serotonergic neurons, was given simultaneously with the lithium chloride, carbidopa and 5-hydroxytryptophan in the threshold dose, as well as with the lithium chloride and 5-hydroxytryptophan given at head twitchevoking dosage, pCPA administration decreased the number of head twitches responses in both experimental models, as well as in the reserpinized mice subjected to the lithium chloride and 5-hydroxytryptophan application. Finally, 5,7-dihydroxytryptamineevoked serotoninergic nerve endings destruction led to absolute inhibition of headtwitch response when observed after the lithium and 5-hydroxytryptophan application. Moreover, the increase by lithium 5-hydroxytryptophan-evoke head twitch response was inhibited by administration of the ritanserine - a 5-HT2 serotonin receptor blocking agent. In summary, our data show that lithium induced an enhancement of serotonergic neurotransmission due to its action on presynaptic serotonergic terminals.

NEW 7-(2-(BENZOL[d]THIAZOL-2-YLAMINO)ETHOXY)-4-METHYL-2HCHROMEN-2-0NE DERIVATIES WITH ATYPICAL ANTIPSYCHOTIC ACTIVITY

A new series of 7-(2-(benzo[d]thiazol-2-ylamino)ethoxy)-4-methyl-2H-chromen-2-one derivatives(4a4k) was synthesized and evaluated for their D2 and 51HT2 antagonistic activity as a measure of atypical antipsychotic properly. Compounds 7-(2-(benzo[d]thiazo/-2-ylamino)ethoxy)-4-methyl-2H-chromen-2- one derivatives (4a-4k) was synthesized by refluxing 2-amino benzothiazoles substituted derivatives (3a3k) and 7-(2-Chloroethoxy)-4-melhyl-2H-chromen-2-one (2) in dry pyridine. The synthesized compounds were characterized with the help of spectral and analytical data. Most of these compounds showed dopamine D2 receptor antagonistic activity from moderate to high potency along with serotonin 5-HT2 receptor blockage activity: a property that has been suggested to be necessary for the atypical nature of antipsychotic agents. The D2 and 5-HT2 receptor blockage activity was evaluated by inhibition of apomorphine-induced climbing behavior and 5HTP induced head twitches in mice respectively.

Synthesis, Computational Studies and Preliminary Pharmacological Evaluation of New Arylpiperazines

A series of novel arylpiperazines were synthesized and the target compounds evaluated for atypical antipsychotic activity in apomorphine induced climbing behavior (D2antagonism), 5-HTP induced head twitches (5-HT2Aantagonism) and catalepsy studies in albino mice. The physicochemical similarity of the target compounds with respect to standard drugs clozapine, ketanserine and risperidone was assessed by calculating from a set of physiochemical properties using software programs. The test compounds(3a-j)demonstrated good similarity values with respect to the standard drugs. Among them, compound3dhas emerged as an important lead compound showing potential atypical antipsychotic like profile.