Neuropharmacology
-
Multiple sclerosis (MS) is an autoimmune disease that affects the CNS and it is characterized by inflammation, demyelination, remyelination, gliosis and axonal damage that occur mainly in the spinal cord. Cannabinoids have been proposed as promising therapeutic agents in MS given their capability to alleviate specific MS symptoms (e.g., spasticity, pain). Although MS has been considered mainly an inflammatory disorder, recent evidence, however, revealed the importance of neurodegenerative events, opening the possibility that cannabinoid agonists, given their cytoprotective properties, may also serve to reduce oligodendrocyte death and axonal damage in MS. ⋯ This was concordant with the lack of positive effects on neurological decline observed in EAE mice when they received HU-308, a selective CB(2) receptor agonist, instead WIN55,212-2. In summary, the treatment of EAE mice with the cannabinoid agonist WIN55,512-2 reduced their neurological disability and the progression of the disease. This effect was exerted through the activation of CB(1) receptors, which would exert a positive influence in the reduction of inflammatory events linked to the pathogenesis of this disease.
-
Comparative Study
Enriched experience and recovery from amblyopia in adult rats: impact of motor, social and sensory components.
Amblyopia is one of the most common forms of visual impairment, arising from an early functional imbalance between the two eyes. It is currently accepted that, due to a lack of neural plasticity,amblyopia is an untreatable pathology in adults. Environmental enrichment (EE) emerged as a strategy highly effective in restoring plasticity in adult animals, eliciting recovery from amblyopia through a reduction of intracortical inhibition. ⋯ These effects were accompanied by a reduced inhibition/excitation balance in the visual cortex. In contrast, we did not detect any sign of recovery in socially enriched rats or in animals practicing a purely associative visual task. These findings could have a bearing in orienting clinical research in the field of amblyopia therapy.
-
A functional interaction between serotonergic and noradrenergic systems has been shown in the locus coeruleus (LC). Noradrenaline (NA) levels in the prefrontal cortex (PFC) are dependent on the firing rate of LC neurons, which is controlled by α(2) adrenoceptors (α2ADR). The aim of the present study was to investigate the role of 5-HT(3) receptors (5HT3R) in the modulation of central noradrenergic activity. ⋯ Administration of RS79948 (1 μM) reversed the inhibition induced by mCPBG. Competition radioligand assays against [(3)H]UK14304 and [(3)H]RX821002 (α2ADR selective drugs) in the rat brain cortex showed a very weak affinity of SR57227 for α2ADR, whereas the affinity of mCPBG for α2ADR was 17-fold higher than that of SR57227 for α2ADR. The present results suggest that 5HT3R stimulate NA release in the LC, which promotes simultaneously a decrease in the firing rate of LC neurons through α2ADR and then a decrease of NA release in terminal areas such as the PFC.
-
Comparative Study
Block of Na+ currents and suppression of action potentials in embryonic rat dorsal root ganglion neurons by ranolazine.
Ranolazine, an anti-anginal drug, reduces neuropathic and inflammatory-induced allodynia in rats. However, the mechanism of ranolazin's anti-allodynic effect is not known. We hypothesized that ranolazine would reduce dorsal root ganglion (DRG) Na(+) current (I(Na)) and neuronal firing by stabilizing Na(+) channels in inactivated states to cause voltage- and frequency-dependent block. ⋯ Ranolazine blocked TTXs and TTXr in a voltage- and frequency-dependent manner. Furthermore, ranolazine (10 μM) blocked hNa(v)1.3 (expressed in HEK293 cells) and caused a hyperpolarizing shift in the voltage dependence of steady-state intermediate and slow inactivation Na(v)1.3 current. Taken together, the results suggest that ranolazine suppresses the hyperexcitability of DRG neurons by interacting with the inactivated states of Na(+) channels and these actions may contribute to its anti-allodynic effect in animal models of neuropathic pain.