Capsaicin-Induced Changes in LTP in the Lateral Amygdala Are Mediated by TRPV1

The transient receptor potential vanilloid type 1 (TRPV1) channel is a well recognized polymodal signal detector that is activated by painful stimuli such as capsaicin. Here, we show that TRPV1 is expressed in the lateral nucleus of the amygdala (LA). Despite the fact that the central amygdala displays the highest neuronal density, the highest density of TRPV1 labeled neurons was found within the nuclei of the basolateral complex of the amygdala. Capsaicin specifically changed the magnitude of long-term potentiation (LTP) in the LA in brain slices of mice depending on the anesthetic (ether, isoflurane) used before euthanasia. After ether anesthesia, capsaicin had a suppressive effect on LA-LTP both in patch clamp and in extracellular recordings. The capsaicin-induced reduction of LTP was completely blocked by the nitric oxide synthase (NOS) inhibitor L-NAME and was absent in neuronal NOS as well as in TRPV1 deficient mice. The specific antagonist of cannabinoid receptor type 1 (CB1), AM 251, was also able to reduce the inhibitory effect of capsaicin on LA-LTP, suggesting that stimulation of TRPV1 provokes the generation of anandamide in the brain which seems to inhibit NO synthesis. After isoflurane anesthesia before euthanasia capsaicin caused a TRPV1-mediated increase in the magnitude of LA-LTP. Therefore, our results also indicate that the appropriate choice of the anesthetics used is an important consideration when brain plasticity and the action of endovanilloids will be evaluated. In summary, our results demonstrate that TRPV1 may be involved in the amygdala control of learning mechanisms

Low-frequency volatility and macroeconomic dynamics: conventional versus Islamic stock markets

This study investigates the relationship between macroeconomic risk and low-frequency volatility of conventional and Islamic stock markets from around the world. Using a panel of 36 countries, representing developed, emerging and Islamic countries for the period from 2000 to 2016, the study finds that low-frequency market volatility is lower for Islamic countries and, markets with more number of listed companies, higher market capitalization relative to GDP and larger variability in industrial production. The study also finds that low-frequency component of volatility is greater when the macroeconomic factors of GDP, unemployment, short-term interest rates, inflation, money supply and foreign exchange rates are more volatile. The empirical results are robust to various alternative specifications and split sample analyses. The findings imply that religiosity has an influence on the correction of market volatility and investors may consider the Islamic stocks to diversify their risks