Vomeronasal activation by urine in the primate Microcebus murinus: a 2 DG study

The vomeronasal system (VNS) seems to be functional in some primates and involved in the detection of urinary signals. Anterograde tracing (WGA-HRP) and evoked metabolic activity (2-DG method) were used in order to clarify the conditions under which the VNS is activated in the prosimian mouse lemur. After WGA-HRP deposition at one of the oral entries of the nasopalatine duct, reaction product was observed within the accessory bulb (AOB). 2-DG experiments show that urine in the volatile phase stimulates the main but not the accessory bulb (AOB). Liquid urine produced bilateral or unilateral activation of AOB depending on whether the stimulation was exclusively unilateral or not; under the same conditions distilled water could not produce 2-DG labelling. It is concluded that VNS is activated by urine in the liquid but not the volatile phase. The biological implications of these results are discussed.