Involvement of adrenoceptors, dopamine receptors and AMPA receptors in antidepressant-like action of 7-O-ethylfangchinoline in mice

Involvement of dopamine D2 and glutamate NMDA receptors in the antidepressant-like effect of amantadine in mice

The present study investigated the pharmacological mechanisms of the antidepressant-like effects of amantadine in mice and their influence on hippocampal neurogenesis. To improve the translational validity of preclinical results, reproducibility across laboratories and replication in other animal models and species are crucial. Single amantadine administration at doses of 50 and 75 mg/kg resulted in antidepressant-like effects in mice in the tail suspension test (TST), reflected by an increase in immobility time. The effects of amantadine were seen at doses that did not alter locomotor activity. The tyrosine hydroxylase inhibitor α-methyl-ρ-tyrosine did not influence the anti-immobility effect of amantadine in the TST. Pretreatment with the α₁ adrenergic receptor antagonist prazosin, β adrenergic receptor antagonist propranolol, α₂ adrenergic receptor antagonist yohimbine, and α₂ adrenergic receptor agonist clonidine did not alter the antidepressant-like effect of amantadine. However, amantadine's effect was blocked by the dopamine D₂ receptor antagonist haloperidol and glutamate receptor agonist N-methyl-D-aspartate (NMDA). Repeated amantadine administration (50 mg/kg) also exerted an antidepressant-like effect, paralleled by an increase in hippocampal neurogenesis. The present results demonstrate that the antidepressant-like effects of amantadine may be mediated by its actions on D₂ and NMDA receptors and likely involve hippocampal neurogenesis.

Molecular Targets Modulated by Fangchinoline in Tumor Cells and Preclinical Models

Despite tremendous progress made during the last few decades in the treatment options for cancer, compounds isolated from Mother Nature remain the mainstay for therapy of various malignancies. Fangchinoline, initially isolated from the dried root of Stephaniae tetrandrine, has been found to exhibit diverse pharmacological effects including significant anticancer activities both in tumor cell lines and selected preclinical models. This alkaloid appears to act by modulating the activation of various important oncogenic molecules involved in tumorigenesis leading to a significant decrease in aberrant proliferation, survival and metastasis of tumor cells. This mini-review briefly describes the potential effects of fangchinoline on important hallmarks of cancer and highlights the molecular targets modulated by this alkaloid in various tumor cell lines and preclinical models.

Tenuifolin, a saponin derived from Radix Polygalae, exhibits sleep-enhancing effects in mice

BACKGROUND

Radix Polygalae, the dried root of Polygala tenuifolia, has been extensively used as a traditional Chinese medicine for promoting intelligence and tranquilization. Polygalasaponins extracted from the root of P. tenuifolia possess evident anxiolytic and sedative-hypnotic activities. Previous studies have reported that tenuifolin was a major constituent of polygalasaponins.

PURPOSE

The currently study aims to investigate the hypnotic effect and possible mechanism of tenuifolin in freely moving mice.

DESIGN/METHODS

The hypnotic effects of tenuifolin (20, 40 and 80mg/kg, p.o.) were assessed by electroencephalographic (EEG) and electromyographic (EMG) analysis. Double-staining immunohistochemistry test was performed to evaluate the neuronal activity of sleep-wake regulating brain areas. High performance liquid chromatograph- electrochemical detection (HPLC-ECD) and ultrafast liquid chromatography-mass spectrometry (UFLC-MS) were used for the detection of neurotransmitters. Locomotor activity was measured by Open-field Test.

RESULTS

Tenuifolin at doses of 40 and 80mg/kg (p.o.) significantly prolonged the total sleep time by increasing the amount of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, associated with the significant increase in the bouts of episodes respectively. After administration of tenuifolin, the cortical EEG power spectral densities during NREM and REM sleep were similar to that of natural sleep (vehicle) and thus compatible with physiological sleep. Double-immunohistochemistry staining test showed that tenuifolin increased the c-Fos positive ratios of GABAergic NREM sleep-promoting neurons in ventrolateral preoptic area (VLPO), cholinergic REM sleep-promoting neurons in laterodorsal tegmental area (LDT) and pontomesencephalic tegmental area (PPT) and decreased the c-Fos positive ratios in wake-promoting neurons (locus coeruleus (LC) and perifornical area (Pef)). Neurotransmitter detections revealed that tenuifolin significantly reduced the noradrenaline (NA) levels in LC, VLPO, PPT and LDT, elevated the GABA levels in VLPO, LC and Pef and increased the acetylcholine (Ach) levels in LDT and PPT. In addition, tenuifolin did not cause any change to locomotor activity.

CONCLUSION

Taken together, these results provide the first experimental evidence of the significant sleep-enhancing effect of tenuifolin in mice. This effect appears to be mediated, at least in part, by the activation of GABAergic systems and/or by the inhibition of noradrenergic systems. Moreover, this study adds new scientific evidence and highlights the therapeutic potential of the medicinal plant P. tenuifolia in the development of phytomedicines with hypnotic properties.

Dopamine D1 and D3 Receptors Modulate Heroin-Induced Cognitive Impairment through Opponent Actions in Mice

BACKGROUND

Chronic abuse of heroin leads to long-lasting and complicated cognitive impairment. Dopamine receptors are critically involved in the impulsive drug-driven behavior and the altered attention, processing speed, and mental flexibility that are associated with higher relapse rates. However, the effects of the different dopamine receptors and their possible involvement in heroin-induced cognitive impairment remain unclear.

METHODS

The 5-choice serial reaction time task was used to investigate the profiles of heroin-induced cognitive impairment in mice. The expression levels of dopamine D1- and D2-like receptors in the prefrontal cortex, nucleus accumbens, and caudate-putamen were determined. The effects of dopamine receptors on heroin-induced impulsivity in the 5-choice serial reaction time task were examined by agonist/antagonist treatment on D1 or D3 receptor mutant mice.

RESULTS

Systemic heroin administration influences several variables in the 5-choice serial reaction time task, most notably premature responses, a measure of motor impulsivity. These behavioral impairments are associated with increased D1 receptor and decreased D3 receptor mRNA and protein levels in 3 observed brain areas. The heroin-evoked increase in premature responses is mimicked by a D1 agonist and prevented by a D1 antagonist or genetic ablation of the D1 receptor gene. In contrast, a D3 agonist decreases both basal and heroin-evoked premature responses, while genetic ablation of the D3 receptor gene results in increased basal and heroin-evoked premature responses.

CONCLUSIONS

Heroin-induced impulsive behavior in the 5-choice serial reaction time task is oppositely modulated by D1 and D3 receptor activation. The D1 receptors in the cortical-mesolimbic region play an indispensable role in modulating such behaviors.