The α7 nAChR allosteric modulator PNU-120596 amends neuroinflammatory and motor consequences of parkinsonism in rats: Role of JAK2/NF-κB/GSk3β/ TNF-α pathway

The neuroprotective effects of alpha lipoic acid in rotenone-induced Parkinson's disease in mice via activating PI3K/AKT pathway and antagonizing related inflammatory cascades

Parkinson's disease (PD) is an idiopathic disease caused by the loss or degeneration of the dopaminergic (dopamine-producing) neurons in the brain and characterized by various inflammatory and apoptotic responses in the neuronal cells. Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) axis is responsible for neuronal survival by providing a number of anti-inflammatory and anti-apoptotic milieu that prevent the progression of PD. Alpha-lipoic acid (ALA) is a natural cofactor that has antioxidant capacity and contributes to various metabolic processes. ALA can penetrate the blood-brain barrier and contribute to numerous neuroprotective effects. It can activate PI3K/AKT pathway with consequent reduction of different inflammatory and oxidative biomarkers. Our work aims to unfold the neuroprotective effects of ALA via targeting PI3k/AKT pathway. Forty male mice were divided into four groups: control, ALA (100 mg/kg/day; i.p.), rotenone (ROT) (1.5 mg/kg/2 days, i.p.) and rotenone + ALA for 21 days. ALA showed obvious neuroprotective effects via significant activation of PI3K/AKT pathway with subsequent decreasing level of Caspase-3. ALA resulted in prominent anti-inflammatory actions by decreasing interlukin-1β (IL-1β), tumor necrosis factor (TNF)-α and nuclear factor kabba (NFk)-B. ALA remarkably induced antioxidant activities via increasing reduced glutathione (GSH) and superoxide dismutase (SOD) levels as well as decreasing malondialdehyde (MDA) level. The substantial behavioral improvement reflected in these results was noticed in the ALA-treated mice as a reflection of the neuroprotective activities of ALA. In conclusion, ALA showed promising neuroprotective effects in rotenone-induced PD via activating the PI3K/AKT pathway and consequent inhibition of apoptotic and inflammatory biomarkers.

Activation of alpha-7 nicotinic acetylcholine receptor by tropisetron mitigates 3-nitropropionic acid-induced Huntington's disease in rats: Role of PI3K/Akt and JAK2/NF-κB signaling pathways

Huntington's disease (HD) is an inheritable autosomal-dominant disorder that targets mainly the striatum. 3-Nitropropionic acid (3-NP) induces obvious deleterious behavioral, neurochemical, and histological effects similar to the symptoms of HD. Our study aimed to examine the neuroprotective activity of tropisetron, an alpha-7 neuronal nicotinic acetylcholine receptor (α-7nAChR) agonist, against neurotoxic events associated with 3-NP-induced HD in rats. Forty-eight rats were randomly allocated into four groups. Group I received normal saline, while Groups II, III and IV received 3-NP for 2 weeks. In addition, Group III and IV were treated with tropisetron 1 h after 3-NP administration. Meanwhile, Group IV received methyllycaconitine (MLA), an α-7nAChR antagonist, 30 min before tropisetron administration. Treatment with tropisetron improved motor deficits as confirmed by the behavioral tests and restored normal histopathological features of the striatum. Moreover, tropisetron showed an anti-oxidant activity via increasing the activities of SDH and HO-1 as well as Nrf2 expression along with reducing MDA level. Tropisetron also markedly upregulated the protein expression of p-PI3K and p-Akt which in turn hampered JAK2/NF-κB inflammatory cascade. In addition, tropisetron showed an anti-apoptotic activity through boosting the expression of Bcl-2 and reducing Bax expression and caspase-3 level. Interestingly, all the aforementioned effects of tropisetron were blocked by pre-administration of MLA, which confirms that such neuroprotective effects are mediated via activating of α-7nAChR. In conclusion, tropisetron showed a neuroprotective activity against 3-NP-induced HD via activating PI3K/Akt signaling and suppressing JAK2/NF-κB inflammatory axis. Thus, repositioning of tropisetron could represent a promising therapeutic strategy in management of HD.

Hydroxyurea interaction with α7 nicotinic acetylcholine receptor can underlie its therapeutic efficacy upon COVID-19

In this paper the authors provide evidence that hydroxyurea (hydroxycarbamide) interacts with α7 nicotinic acetylcholine receptor, exerts anti-inflammatory and pro-survival effect, prevents α7 nicotinic receptor interaction with angiotensin-converting enzyme-2 and stimulates IgM to IgG class switch upon immunization with SARS spike protein fragment 674-685. Hydroxyurea shifts immunoglobulin glycosylation profile to anti-inflammatory phenotype and prevents the appearance of anti-idiotypic α7(179-190)-specific antibodies, as well as memory impairment. According to these results, interaction with α7 nicotinic acetylcholine receptor may underlie positive therapeutic effects of hydroxyurea upon SARS-Cov-2 infection by interfering with virus penetration into the cell and providing anti-inflammatory and immunomodulatory effects.

Exposure to short-chain chlorinated paraffins induces astrocyte activation via JAK2/STAT3 signaling pathway

In the last few decades, short-chain chlorinated paraffins (SCCPs) have become the most heavily produced monomeric organohalogen compounds, and have been reported to induce multiple organ toxicity. However, the effects of SCCPs on the central nervous system are unknown. In the present study, we show that SCCP exposure induced astrocyte proliferation and increased the expression of two critical markers of astrocyte activation, glial fibrillary acidic protein and inducible nitric oxide synthase, in vivo and in vitro. SCCP exposure also increased inflammatory factory gene expression. Moreover, SCCP treatment triggered Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signalling, as shown by increased phosphorylation and STAT3 translocation to the nucleus. Both JAK2 and STAT3 inhibition effectively attenuated SCCP-induced astrocyte activation. Finally, JAK2 inhibition significantly rescued STAT3 phosphorylation and nuclear translocation. Taken together, JAK2/STAT3 pathway activation contributed to SCCP-induced astrocyte activation. These data will help elucidate the molecular mechanism underlying SCCP-induced neurotoxicity.