The mother rat's vomeronasal organ is involved in detection of dodecyl propionate, the pup's preputial gland pheromone

The aim of the present study was to analyze the respective roles of main and accessory olfactory systems in a particular pattern of Wistar rat maternal behavior: specific licking of pup's anogenital areas, a behavioral pattern crucial to pup survival-nonlicked pups cannot defecate, and die. Dodecyl propionate (DP), a chemical agent from rat pup's preputial glands was found to direct and regulate pup's anogenital licking. Primiparous dams underwent one of the following treatments: surgical removal of the vomeronasal organ (hereafter VNX), irrigation of nasal cavities with 5% ZnSO4 solution (ZN), both these treatments (VNX + ZN), surgical control (SC), saline irrigation control (SA), both these treatments (SC + SA), and normal control (N). Fewer pups (only 75%) of VNX dams survived to 15 days of age compared to controls or to females rendered anosmic by zinc-sulfate irrigation of the nasal cavity (>95% survival). Furthermore, pup growth (mass increase over time) was impaired by VNX and/or ZN treatment. Greater than normal amounts of time were spent licking pups' anogenital area by VNX females, although these darns did not spend as much time as normal females in close contact with either pups heads or filter papers anointed with dodecyl propionate. The experiments reported herein suggest that the chemosensory receptors in the vomeronasal organ of darns mediate MAGL responses to pup pheromone, dodecyl propionate, a pheromone from pups' preputial glands secretion, sustaining pups' anogenital licking by darns. (C) 1999 Elsevier Science Inc.