Molecular-docking-guided design and synthesis of new IAA-tacrine hybrids as multifunctional AChE/BChE inhibitors.

A series of new indole-3-acetic acid (IAA)-tacrine hybrids as dual acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) inhibitors were designed and prepared based on the molecular docking mode of AChE with an IAA derivative (1a), a moderate AChE inhibitor identified by screening our compound library for anti-Alzheimer's disease (AD) drug leads. The enzyme assay results revealed that some hybrids, e.g. 5d and 5e, displayed potent dual in vitro inhibitory activities against AChE/BChE with IC50 values in low nanomolar range. Molecular modeling studies in tandem with kinetic analysis suggest that these hybrids target both catalytic active site and peripheral anionic site of cholinesterase (ChE). Molecular dynamic simulations and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) calculations indicate that 5e has more potent binding affinity than hit 1a, which may explain the stronger inhibitory effect of 5e on AChE. Furthermore, their predicted pharmacokinetic properties and in vitro influences on mouse brain neural network electrical activity were discussed. Taken together, compound 5e can be highlighted as a lead compound worthy of further optimization for designing new anti-AD drugs.

Design and synthesis of pregnenolone/2-cyanoacryloyl conjugates with dual NF-κB inhibitory and anti-proliferative activities.

Twenty-five novel pregnenolone/2-cyanoacryloyl conjugates (6-30) were designed and prepared, with the aim of developing novel anticancer drugs with dual NF-κB inhibitory and anti-proliferative activities. Compounds 22 and 27-30 showed inhibition against TNF-α-induced NF-κB activation in luciferase assay, which was confirmed by Western blotting. Among them, compound 30 showed potent NF-κB inhibitory activity (IC50=2.5µM) and anti-proliferative against MCF-7, A549, H157, and HL-60 cell lines (IC50=6.5-36.2µM). The present study indicated that pregnenolone/2-cyanoacryloyl conjugate I can server asa novel scaffold for developing NF-κB inhibitors and anti-proliferative agents in cancer chemotherapy.

Functional coupling between the prefrontal cortex and dopamine neurons in the ventral tegmental area.

Stimulation of the prefrontal cortex (PFC) has been shown to have an excitatory influence on dopamine (DA) neurons. We report here that, under nonstimulated conditions, the activity of DA neurons in the ventral tegmental area (VTA) also covaries, on a subsecond timescale, with the activity of PFC cells. Thus, in 67% of VTA DA neurons recorded in chloral hydrate-anesthetized rats, the firing of the cell displayed a slow oscillation (SO) that was highly coherent with the activity of PFC neurons. The SO was suppressed by transections immediately caudal to the PFC or by intra-PFC infusion of tetrodotoxin, suggesting that it depends on inputs derived from the PFC. Unexpectedly, the SO in most VTA DA neurons was reversed in phase relative to PFC cell activity, suggesting that at least part of PFC information is transferred to DA neurons indirectly through inhibitory relay neurons. These results, together with those reported previously, suggest that the PFC can act through multiple pathways to exert both excitatory and inhibitory influences on DA neurons. The observed functional coupling between DA and PFC neurons further suggests that these pathways not only allow a bidirectional control of DA neurons by the PFC, but also enable action potential-dependent DA release to be coordinated, on a subsecond timescale, with glutamate release from PFC terminals. Further understanding of this coordinated activity may provide important new insights into brain functions and disorders thought to involve both VTA DA and PFC neurons.

Cocaine-induced locomotor sensitization associates with slow oscillatory firing of neurons in the ventral tegmental area.

The initiation of psychostimulant sensitization depends on the mesocorticolimbic dopamine (DA) system. Although many cellular adaptations has been reported to be associated with this addictive behavior, the overall influence of these adaptations on the network regulation of DA neurons has not been established. Here, we profile a network-driven slow oscillation (SO) in the firing activity of ventral tegmental area (VTA) putative DA and non-DA neurons and their correlation with locomotor sensitization induced by repeated administration of cocaine. One day after the last cocaine injection, the power of SO (Pso) significantly increased both in DA and non-DA neurons. Interestingly, the Pso in DA neurons was positively correlated, while Pso in non-DA neurons was negatively correlated with the level of locomotor sensitization. On the other hand, the firing rates of DA and non-DA neurons were both elevated, but none exhibited any correlation with the level of sensitization. Fourteen days after the last injection, the Pso of DA neurons dissipated but still positively correlated with the level of sensitization. In contrast, the Pso in non-DA neurons lost correlation with locomotor sensitization. These results suggest that cocaine-induced locomotor sensitization is associated with long-term network adaptation in DA system and that DA and non-DA neurons may corporately facilitate/hamper the initiation of locomotor sensitization.

GABA neurons in the ventral tegmental area responding to peripheral sensory input.

Dopamine (DA) neurons in the ventral tegmental area (VTA) not only participate in reward processing, but also respond to aversive stimuli. Although GABA neurons in this area are actively involved in regulating the firing of DA neurons, few data exist concerning the responses of these neurons to aversive sensory input. In this study, by employing extracellular single-unit recording and spectral analysis techniques in paralyzed and ventilated rats, we found that the firing pattern in 44% (47 of 106) of GABA cells in the VTA was sensitive to the sensory input produced by the ventilation, showing a significant ventilation-associated oscillation in the power spectra. Detailed studies revealed that most ventilation-sensitive GABA neurons (38 of 47) were excited by the stimuli, whereas most ventilation-sensitive DA neurons (11 of 14) were inhibited. When the animals were under anesthesia or the sensory pathways were transected, the ventilation-associated oscillation failed to appear. Systemic administration of non-competitive N-methyl-D-aspartase (NMDA) receptor antagonist MK-801 completely disrupted the association between the firing of GABA neurons and the ventilation. Interestingly, local MK-801 injection into the VTA dramatically enhanced the sensitivity of GABA neurons to the ventilation. Our data demonstrate that both GABA and DA neurons in the VTA can be significantly modulated by sensory input produced by the ventilation, which may indicate potential functional roles of VTA in processing sensation-related input.

Alpha-mangostin suppresses PC-3 human prostate carcinoma cell metastasis by inhibiting matrix metalloproteinase-2/9 and urokinase-plasminogen expression through the JNK signaling pathway.

Alpha-mangostin, a component of Garcinia mangostana Linn, is a xanthone derivative shown to have antioxidant and anticarcinogen properties. In this study, we first report the antimetastatic effect of alpha-mangostin in the human prostate carcinoma cell line PC-3. The results show that alpha-mangostin exhibited an inhibitory effect on the abilities of adhesion, migration, and invasion by cell-matrix adhesion assay, wound healing assay, and Boyden chamber assay. In the cancer cell metastasis process, matrix degrading proteinases are required. Results from zymography showed that alpha-mangostin treatment could decrease the expressions of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and urokinase-plasminogen activator (u-PA) in a concentration-dependent manner. Moreover, alpha-mangostin also exerted an inhibitory effect on phosphorylation of c-Jun N-terminal kinase 1 and 2 (JNK1/2) and inhibition of activation of nuclear factor kappa B (NF-kappaB), c-Fos, and c-Jun. Furthermore, the treatment of inhibitors specific for JNK (SP600125) to PC-3 cells could result in a reduced expression of MMP-2, MMP-9, and u-PA. These results demonstrated that alpha-mangostin could mediate PC-3 cells metastasis by reduction of MMP-2, MMP-9, and u-PA expression through the suppression of the JNK1/2 signaling pathway and inhibition of NF-kappaB and AP-1 binding activity. These findings proved that alpha-mangostin might be offered further application as an antimetastatic agent.

l-Stepholidine increases the frequency of sEPSC via the activation of D1 dopamine signaling pathway in rat prelimbic cortical neurons.

AIM: To investigate the effect of l-stepholidine (SPD) on the frequency of spontaneous excitatory postsynaptic currents (sEPSC) in the pyramidal cells between layers V and VI in the prelimbic cortex (PL). METHODS: A whole-cell patch clamp in rat brain slices was used. RESULTS: SPD significantly increased the frequency of sEPSC in a concentration-dependent manner. A selective D1 dopamine receptor antagonist SCH23390 blocked SPD-mediated effects, whereas the D1 agonist SKF38393, but not the D2/3 antagonist sulpiride, mimicked SPD-mediated increase in the frequency of sEPSC. Moreover, both protein kinase A (PKA) inhibitor N-(2- [p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide hydrochloride and protein kinase C (PKC) inhibitor chelerythrine attenuated the effect of SPD on sEPSC. CONCLUSION: SPD elicits its effect on the frequency of sEPSC on the PL pyramidal cells via presynaptic D1 receptors, and is dependent on PKA and PKC signaling pathways.