Microinjection of ritanserin into the CA1 region of hippocampus improves scopolamine-induced amnesia in adult male rats

Extrasynaptic GABAA receptors in central medial thalamus mediate anesthesia in rats

Neuronal depression in the thalamus underlies anesthetic-induced loss of consciousness, while the precise sub-thalamus nuclei and molecular targets involved remain to be elucidated. The present study investigated the role of extrasynaptic GABAA receptors in the central medial thalamic nucleus (CM) in anesthesia induced by gaboxadol (THIP) and diazepam (DZP) in rats. Local lesion of the CM led to a decrease in the duration of loss of righting reflex induced by THIP and DZP. CM microinjection of THIP but not DZP induced anesthesia. The absence of righting reflex in THIP-treated rats was consistent with the increase of low frequency oscillations in the delta band in the medial prefrontal cortex. CM microinjection of GABAA receptor antagonist SR95531 significantly attenuated the anesthesia induced by systemically-administered THIP, but not DZP. Moreover, the rats with declined expression of GABAA receptor δ-subunit in the CM were less responsive to THIP or DZP. These findings explained a novel mechanism of THIP-induced loss of consciousness and highlighted the role of CM extrasynaptic GABAA receptors in mediating anesthesia.

Cognitive-enhancing and ameliorative effects of acanthoside B in a scopolamine-induced amnesic mouse model through regulation of oxidative/inflammatory/cholinergic systems and activation of the TrkB/CREB/BDNF pathway

Recently, our research team reported the anti-amnesic potential of desalted-hydroethanolic extracts of Salicornia europaea L. (SE-EE). In this study, we performed bioactivity-guided isolation and identification of Acanthoside B (Aca.B), from SE-EE, as the potential bioactive candidate and examined anti-amnesic activity with its potential mechanism of action using an in vivo model. S7-L3-3 purified from SE-EE showed enhanced in vitro acetylcholinesterase (AChE) inhibitory activity. The isolated S7-L3-3 was identified and characterized as Aca.B using varied spectral analyses, i.e., Nuclear magnetic resonance (NMR), Ultraviolet-visible (UV-Vis), and Electrospray ionization-mass spectrometry (ESI-MS). In the in vitro studies, Aca.B exhibited negligible toxicity and showed a dose-dependent nitric oxide inhibitory potential in Lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. In the in vivo studies, the oral administration of Aca.B to mice showed enhanced bioavailability and dose-dependent repression of the behavioral/cognitive impairment by regulating the cholinergic function, restoring the antioxidant status, attenuating the inflammatory cytokines/mediators and actively enriching neurotropic proteins in the hippocampal regions of the scopolamine-administered mice.

Triphenyl phosphonium coated nano-quercetin for oral delivery: Neuroprotective effects in attenuating age related global moderate cerebral ischemia reperfusion injury in rats

Cerebral ischemia-reperfusion is a classic example of reactive oxygen species (ROS) mediated acute damage to brain. Post-ischemic reperfusion induced oxygen free radicals production causes damage to brain cell mitochondria. Antioxidants like quercetin (Qc) have potentials to manage oxidative stress related pathophysiology. However low oral bioavailability and poor cell membrane permeability restrict its therapeutic efficacy. To overcome these hurdles mitochondria specific delivery of Qc nanocapsules was designed to efficiently counteract cerebral ischemia-reperfusion induced cell death and neurodegeneration in young and aged rats. The orally deliverable quercetin loaded polymeric nanocapsules (N1QC) were made mitochondria specific by using triphenylphosphonium cation as one of the matrix components. N1QC demonstrated higher brain uptake and remarkable mitochondrial localization post cerebral ischemia-reperfusion. This unique controlled mitochondrial delivery of quercetin ameliorated histopathological severity by preserving mitochondrial structural and functional integrity through sequestering ROS thus modulating mitochondrial ROS mediated apoptotic cell death in young and aged rats.

Bacopa monniera Attenuates Scopolamine-Induced Impairment of Spatial Memory in Mice

Scopolamine, an anticholinergic, is an attractive amnesic agent for discerning the action of candidate antiamnesic drugs. Bacopa monniera Linn (Syn. Brahmi) is one such antiamnesic agent that is frequently used in the ancient Indian medical system. We have earlier reported the reversal of diazepam-induced amnesia with B. monniera. In this study we wanted to test if scopolamine-induced impairment of spatial memory can also be ameliorated by B. monniera using water maze mouse model. The objective of study was to study the effect of B. monniera on scopolamine-induced amnesia. We employed Morris water maze scale to test the amnesic effect of scopolamine and its reversal by B. monniera. Rotarod test was conducted to screen muscle coordination activity of mice. Scopolamine significantly impaired the acquisition and retrieval of memory producing both anterograde and retrograde amnesia. Bacopa monniera extract was able to reverse both anterograde and retrograde amnesia. We propose that B. monniera's effects on cholinergic system may be helpful for developing alternative therapeutic approaches for the treatment of Alzheimer's disease.