GLUTAMATE AND VASOPRESSIN INTERACT TO CONTROL SCENT MARKING IN SYRIAN-HAMSTERS (MESOCRICETUS-AURATUS)

In Syrian hamsters, vasopressin (AVP) in the medial preoptic-anterior hypothalamus (MPOA-AH) controls a form of scent marking called flank m arking. Another neurochemical signal that may interact with AVP to con trol flank marking is glutamate. We tested the hypothesis that glutama te interacts with AVP in the MPOA-AH to regulate flank marking. On day 1, AVP was microinjected into the MPOA-AH. On day 2, AVP was microinj ected as a cocktail combining either AP-5, a NMDA antagonist, or GAMS, a non-NMDA antagonist or propranolol, a beta norepinephrine antagonis t. On day 3, AVP alone was microinjected. Hamsters engaged in high lev els of marking in response to AVP alone or to a combination of AVP and propranolol. In contrast, the frequency of marking was significantly reduced in response to a combination of either AVP and AP-5 or AVP and GAMS. These data support the hypothesis that stimulation of flank mar king by AVP within the MPOA-AH requires the activity of glutamate.