The abuse of inhaled chemical vapors is a growing problem especially among adolescent populations. This is partly driven by the fact that inhaled products are cheap, accessible, and provide a rapid ‘high’. In the brain inhalants have multiple effects. They are neurotoxic, targeting primarily white matter pathways, which is believed to underlie the long-term neurological consequences associated with repeated use. Inhalants are also addictive, resulting in adaptive responses in pathways mediating reward and reinforcement. This includes an ability to alter dopaminergic cell firing and result in long-term mesocorticolimbic dopaminergic dysfunction. However, growing evidence suggests that the reinforcing properties of inhalants may also be driven by their ability to affect neurotransmitter systems other than the dopaminergic system. Both glutamatergic and g-aminobutyric acid (GABA)ergic systems are emerging as key targets of inhalants with differential responses observed following either acute or chronic exposures. These responses appear particularly important in circuits which appear vulnerable to inhalants and which can also modulate dopaminergic function such as the corticostriatal pathway. Thus in combination with the effects of inhalants on dopaminergic systems, our increased understanding of the role(s) of glutamatergic and GABAergic systems provide new and exciting targets to consider for intervention strategies to limit inhalant use.

View full abstract

Low-voltage-activated T-type Ca²⁺ channels (T-channels), especially Ca_v3.2 among the three isoforms (Ca_v3.1, Ca_v3.2, and Ca_v3.3), are now considered to play pivotal roles in processing of pain signals. Ca_v3.2 T-channels are functionally modulated by extracellular substances such as hydrogen sulfide and ascorbic acid, by intracellular signaling molecules including protein kinases, and by glycosylation. Ca_v3.2 T-channels are abundantly expressed in both peripheral and central endings of the primary afferent neurons, regulating neuronal excitability and release of excitatory neurotransmitters such as substance P and glutamate, respectively. Functional upregulation of Ca_v3.2 T-channels is involved in the pathophysiology of inflammatory, neuropathic, and visceral pain. Thus, Ca_v3.2 T-channels are considered to serve as novel targets for development of drugs for treatment of intractable pain resistant to currently available analgesics.

View full abstract

Mithramycin A (MTM) has been shown to inhibit cancer growth by blocking the binding of Sp-family transcription factors to gene regulatory elements and is used for the treatment of leukemia and testicular cancer in the United States. In contrast, MTM has also been shown to exert neuroprotective effects in normal cells. An earlier study showed that MTM protected primary cortical neurons against oxidative stress–induced cell death. Recently, we demonstrated that MTM suppressed endoplasmic reticulum (ER) stress–induced neuronal death in organotypic hippocampal slice cultures and cultured hippocampal cells through attenuation of ER stress–associated signal proteins. We also found that MTM decreased neuronal death in area CA1 of the hippocampus after transient global ischemia/reperfusion in mice and restored the ischemia/reperfusion-induced impairment of long-term potentiation in this area. MTM has been shown to prolong the survival of Huntington’s disease model mice and to attenuate dopaminergic neurotoxicity in mice after repeated administration of methamphetamine. In this review, we provide an up to date overview of neuroprotective effects of MTM and less toxic MTM analogs, MTM SK and MTM SDK, on some of the neurodegenerative diseases and discuss the promise of MTM as an agent for developing new therapeutic drugs for such diseases.

View full abstract

Cognitive deficits and behavioral and psychological symptoms of dementia (BPSD) are typical features of patients with dementia such as Alzheimer’s disease (AD), vascular dementia (VD), and other forms of senile dementia. Clinical evidence has demonstrated the potential usefulness of chotosan (CTS) and yokukansan (YKS), traditional herbal formulations called Kampo medicines, in the treatment of cognitive disturbance and BPSD in dementia patients, although the indications targeted by CTS and YKS in Kampo medicine differ. The availability of CTS and YKS for treating dementia patients is supported by preclinical studies using animal models of dementia that include cognitive/emotional deficits caused by aging and diabetes, dementia risk factors. These studies have led not only to the concept of a neuronal basis for the CTS- and YKS-induced amelioration of cognitive function and emotional/psychiatric symptom–related behavior in animal models, but also to a proposal that ingredient(s) of Uncariae Uncis cum Ramulus, a medicinal herb included in CTS and YKS, may play an important role in the actions of these formulae in dementia patients. Further studies are needed to clarify the active ingredients of these formulae and their target endogenous molecules implicated in the anti-dementia drug-like actions.

View full abstract

The aim of this study was to characterize pharmacological effects of gosha-jinki-gan (GJG) and green tea extract (GTE), on urodynamic parameters, bladder receptors, and urinary cytokines in rats with cyclophosphamide (CYP)-induced cystitis. Urodynamic parameters in CYP-treated rats were measured using the cystometric method. Muscarinic and purinergic receptors in rat tissues were measured by radioreceptor assays. Urinary cytokine levels were measured with ELISA kits. GJG and GTE were orally administered to rats once a day for 7 days. The GJG treatment significantly ameliorated changes in urodynamic parameters in CYP-treated rats. Similar treatment with GTE slightly attenuated changes in urodynamic parameters. The maximal number of binding sites for [³H]NMS and [³H]αβ-MeATP in the bladder was significantly lower in CYP-treated rats than in sham rats. Such a reduction in receptor density was significantly attenuated by the GJG treatment. GTE treatment also significantly attenuated the down-regulation of muscarinic receptors, but not P2X receptors in bladders of rats with CYP-induced cystitis. The elevation in urinary cytokine levels in CYP-treated rats was effectively attenuated by GJG treatment. The elevation in cytokine levels in CYP-treated rats was alleviated by GTE treatment. In conclusion, GJG may be a pharmacologically useful plant extract for cystitis.

View full abstract

To examine the effects of the Akt/mammalian target of rapamycin (mTOR) pathway on masseter muscle hypertrophy and myosin heavy chain (MHC) transition in response to mechanical overload, we analyzed the effects of bite-opening (BO) on the hypertrophy and MHC composition of masseter muscle of BO-rats treated or not treated with rapamycin (RAPA), a selective mTOR inhibitor. The masseter muscle weight in BO-rats was significantly greater than that in controls, and this increase was attenuated by RAPA treatment. Expression of slow-twitch MHC isoforms was significantly increased in BO-rats with/without RAPA treatment, compared with controls, but the magnitude of the increase was much smaller in RAPA-treated BO-rats. Phosphorylation of p44/42 MAPK (ERK1/2), which preserves fast-twitch MHC isoforms in skeletal muscle, was significantly decreased in BO-rats, but the decrease was abrogated by RAPA treatment. Calcineurin signaling is known to be important for masseter muscle hypertrophy and fast-to-slow MHC isoform transition, but expression of known calcineurin activity modulators was unaffected by RAPA treatment. Taken together, these results indicate that the Akt/mTOR pathway is involved in both development of masseter muscle hypertrophy and fast-to-slow MHC isoform transition in response to mechanical overload with inhibition of the ERK1/2 pathway and operates independently of the calcineurin pathway.

View full abstract

The present study investigated the effect of acamprosate on ethanol (EtOH)-induced place preference in mice with EtOH physical dependence. The expression of EtOH (2 g/kg, intraperitoneally)-induced place preference in mice without EtOH treatment before the experiment was dose-dependently suppressed by acamprosate. The levels of protein kinase A (PKA) and phospho-cAMP response element binding protein (p-CREB) in the limbic forebrain after EtOH-conditioning in naïve mice was unchanged. Furthermore, mice on the 4th day of withdrawal from continuous EtOH vapor inhalation for 9 days showed transient and significant enhancement of EtOH (1 g/kg, intraperitoneally)-induced place preference, which was significantly suppressed by acamprosate (300 mg/kg, oral administration; p.o., once a day) administered daily for 3 days after withdrawal from EtOH inhalation and during EtOH-conditioning. PKA and p-CREB proteins in the limbic forebrain of EtOH-conditioned mice on 4th day of withdrawal from continuous EtOH inhalation for 9 days significantly increased, which were completely abolished by acamprosate. These findings suggest that the signal transduction pathway via the PKA–p-CREB pathway in the limbic forebrain may be functionally related to the development of sensitization of EtOH-induced place preference and provide a possible molecular basis for the pharmacological effect of acamprosate to prevent or reduce the relapse of alcohol dependence.

View full abstract

Multiple drug resistance (MDR) occurring during chemotherapy is a major obstacle for treatment of cancers using chemotherapeutic drugs; thus, the mechanisms underlying MDR have attracted intensive attention. Many studies have shown that tumor-initiating cells exhibit a chemotherapeutic tolerance characteristic. However, whether the MDR cells possess tumor-initiating cells properties and its underlying mechanisms remain to be fully elucidated. In this study, we utilized a well-established MDR cell line K562/A02 enriched by doxorubicin from K562 cells to determine if the K562/A02 cells possess tumor-initiating properties and investigated its potential molecular mechanisms. We observed that the expressions of Oct4, Sox2, and Nanog, all of which are well-characterized stem cell markers, in K562/A02 cells were elevated in comparison to parental K562 cells; in addition, we found that K562/A02 cells exhibited more potent in vitro and in vivo tumor-initiating properties, as revealed by sphere assay, self-renewal assay, soft agar assay, and animal studies. Furthermore, our data suggest that snail and twist1, two well known transcriptional factors for the epithelial-mesenchymal transition (EMT) program, may be potentially involved in the acquisition of tumor-initiating properties of K562/A02 cells. Thus, our study demonstrates that MDR K562/A02 cells possess tumor-initiating properties, most likely due to the elevated expressions of snail and twist1.

View full abstract

An accumulating body of evidence suggests that Alzheimer’s disease (AD) is associated with microglia-mediated neuroinflammation and pro-inflammatory cytokine expression. Therefore, the suppression of neuroinflammation and pro-inflammatory cytokine might theoretically slow down the progression of AD. Xanthoceraside, a novel triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge, has potent antiinflammatory and neuroprotective effects. However, the molecular mechanism underlying its anti-inflammatory action remains unclear. In the present study, we attempted to determine the effects of xanthoceraside on the production of pro-inflammatory mediators in amyloid β_25–35 (Aβ_25–35) / interferon-γ (IFN-γ)-stimulated microglia. Our results indicated that xanthoceraside (0.01 and 0.1 μM) significantly inhibited the release of nitric oxide (NO) and pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α in a concentration-dependent manner. Reverse transcriptase–polymerase chain reaction and western blotting analyses showed that xanthoceraside decreased the Aβ_25–35/IFN-γ–induced production of cyclooxygenase-2 and inducible NO synthase. These effects were accompanied by inhibited activities of nuclear factor-κB and mitogen-activated protein kinase through Toll-like receptor 2 in a myeloid differentiation protein 88–dependent manner. Our results provide support for the therapeutic potential of xanthoceraside in AD.

View full abstract

Pre-chondrocytes undergo cellular differentiation stages during chondrogenesis under the influence by different transcription factors such as sry-type high mobility group box-9 (Sox9) and runt-related transcription factor-2 (Runx2). We have shown upregulation by parathyroid hormone (PTH) of the clock gene Period-1 (Per1) through the cAMP/protein kinase A signaling pathway in pre-chondrocytic ATDC5 cells. Here, we investigated the role of Per1 in the suppression of chondrogenic differentiation by PTH. In ATDC5 cells exposed to 10 nM PTH, a drastic but transient increase in Per1 expression was seen only 1 h after addition together with a prolonged decrease in Sox6 levels. However, no significant changes were induced in Sox5 and Runx2 levels in cells exposed to PTH. In stable Per1 transfectants, a significant decrease in Sox6 levels was seen, with no significant changes in Sox5 and Sox9 levels, in addition to the inhibition of gene transactivation by Sox9 allies. Knockdown of Per1 by siRNA significantly increased the Sox6 and type II collagen levels in cells cultured for 24 – 60 h. These results suggest that Per1 plays a role in the suppressed chondrocytic differentiation by PTH through a mechanism relevant to negative regulation of transactivation of the Sox6 gene during chondrogenesis.

View full abstract