DEFINITION of 'Commercial'. Relating to commerce. In the investment field, the term commercial is generally used to refer to a trading entity engaged in business activities that are hedged by positions in the futures or options markets.
The melanocortin 1 receptor controls which type of melanin is produced by melanocytes. When the receptor is activated, it triggers a series of chemical reactions inside melanocytes that stimulate these cells to make eumelanin. If the receptor is not activated or is blocked, melanocytes make pheomelanin instead of eumelanin.
An early recognized function of astrocytes is the control of K + levels in the brain. Neuronal activity leads to an increase in K + concentration from a resting level of about 3 mM to a maximum of 10 - 12 mM under physiological conditions and to even higher values under pathological conditions.strocytes may also limit the number of synapses since astrocyte membranes can ensheath the neuronal processes and thus compete with synapses. Astroglial cells can also be involved in the elimination of synapses in the CNS, the process which underlies the final tuning and plasticity of the neuronal inputs.