Control of attractivity and receptivity in female red-sided garter snakes

Female red-sided garter snakes emerge from their hibernacula in the spring attractive and receptive to males. Attractivity is communicated by a pheromone released through the female's skin and is a consequence of ovarian recrudescence the previous summer. Receptivity, on the other hand, is stimulated by ovarian estrogen secretion during emergence itself. Mating renders females both unattractive and unreceptive. Another "mating" pheromone of male origin is important in making females unattractive after mating. To investigate the role of cloacal stimulation in the loss of attractivity and receptivity we injected a local anesthetic (lidocaine or tetracaine) in the cloacal region of females before mating. This does not prevent mating, although it blocks neural transmission of copulatory sensory stimuli. The time course of transition from attractive and receptive states was then observed. Females treated with local anesthetic as well as control females were unattractive within 15 min of mating. However, when retested 2-3 and 24 h after mating, a significantly higher proportion of treated females regained their attractivity, while mated control females remained unattractive. This restorative effect was transient, though, as treated females retested 48 h after mating were as unattractive as the controls. Both anesthetized and control females were unreceptive when tested following mating and did not regain receptivity with time. Last, the mating-induced surge in circulating concentrations of prostaglandin was diminished in females that received a local anesthetic prior to mating. Taken together these results indicate that the loss of attractivity and receptivity following mating in the red-sided garter snake is due to combined effects of a mating pheromone and a physiological, neurally mediated response to the sensation of stimuli associated with the act of mating.