Figure 1.

Schematic illustration of the effects of carbamates on neuronal ACh, and the hypothetical effects on non-neuronal ACh in the male reproductive system. Image right side: (a). ACh vesicles (red dots) are released to the synaptic clef, where they will bind to its receptors, while the excess is converted into acetic acid (green dots) and choline (purple dots), by the AChE. Choline is then taken up by the neuron to be resynthesized into new ACh. (b). Inhibition of AChE, upon exposure to carbamates, increases the levels of ACh on the synaptic cleft, thus producing its toxic effects. Image left side: ACh increases sperm motility through the stimulation of Ca²⁺ influx into the spermatozoa. Abbreviations: ACh—acetylcholine; AChE—acetylcholinesterase enzyme; AChR—acetylcholine receptor; CaCh-Ca²⁺ channels.