Yeah the chart might seem a bit overwhelming at the first glance, but its not that difficult to comprehend once you realize the roles of the receptors and ions involved in the activity of various receptor ligands. So let me break it down for you to as how I see and understand it:
Ca2+ ions are initiators of neural transmissions, Calcium ion influx is generally the first step behind the liberation of neurotransmitters (such as Serotonin, Nor-Adrenaline, Glutamate and many more) from their center of residence (synaptic vesicle in the presynaptic neurone) into the synaptic cleft where they bind to the receptor sites of the post-synaptic neuron which then elicits a corresponding physiological response. Therefore the decrease in Ca2+ (as CBD does according to the chart) will result in less transmission, which can alleviate possible excitotoxicity (too much transmission at excitatory synapses can have neurotoxic effects: e.g excess release of glutamate in depressed patients) thus will serve a neuro-protective role in this case.
5HT1A (+) indicates that CBD is an agonist at the serotonin receptor labeled as 5HT1A. The same action exhibits buspirone, which is an anxiolytic and anti-depressant. (-) Would indicate an antagonist............................................................................................................................................................................................................................................................................................................................
