Abstract
These experiments were designed to determine whether the parity difference in robustness of a maternal experience reflects a parity difference in the reinforcing value of pups and factors affecting pup reinforcement. Postpartum and virgin animals were exposed for 15, 30, or 60 min to a novel environment (either a horizontally or vertically striped box) in the presence or absence of pups (or food stimuli) over a 2-, 4-, or 8-day period and then tested for their box preference in a two-choice conditioned place preference paradigm. Postpartum animals preferred the pup-associated box to the alternative box; nulliparous animals did not. The reverse pattern was found when food, rather than pups, was paired with the distinctive environment. However, if nulliparous animals were induced to become maternal either by induction procedures or by hormonal manipulation, they also preferred the pup-associated box. The effect was most robust when animals were stimulated to be maternal by hormones. Finally, pup reinforcement shares properties with other types of reinforcers in being dependent on the functional integrity of the dopamine system. Postpartum animals treated with cis(Z)-flupentixol, a dopamine antagonist, do not develop a conditioned place preference when pups are the reinforcing stimulus. Taken together, these experiments show that pups are potent reinforcers to the maternal animal, regardless of how animals become maternal, but that the hormones of parturition may augment these effects. They show further that pup reinforcement, like food or drug reinforcement, is dopamine dependent.
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Bechara, A. (1991). The neurobiology of motivation: Double dissociation of motivational effects under deprivation versus nondeprivation conditions. Unpublished doctoral dissertation, University of Toronto.
Bechara, A., Harrington, F., Nader, K., & van der Kooy, D. (1992). Neurobiology of motivation: Double dissociation of two motivational mechanisms mediating opiate reward in drug-naive versus drug-dependent animals. Behavioral Neuroscience, 106, 798–807.
Bechara, A., & van der Kooy, D. (1989). The tegmental pedunculopontine nucleus: A brain-stem output of the limbic system critical for the conditioned place preferences produced by morphine and amphetamine. Journal of Neuroscience, 9, 3400–3409.
Bridges, R. S. (1975). Long-term effects of pregnancy and parturition upon maternal responsiveness in the rat. Physiology & Behavior, 14, 245–249.
Bridges, R. S. (1977). Parturition: Its role in the long term retention of maternal behavior in the rat. Physiology & Behavior, 18, 487–490.
Cohen, J., & Bridges, R. S. (1981). Retention of maternal behavior in nulliparous and primiparous rats: Effects of duration of previous maternal experience. Journal of Comparative & Physiological Psychology, 95, 450–459.
Fleming, A. S., Kuchera, C., Lee, A., & Winocur, G. (1994). Olfactory-based social learning varies as a function of parity in female rats. Psychobiology, 22, 37–43.
Fleming, A. S., & Sarker, J. (1990). Experience-hormone interactions and maternal behavior in rats. Physiology & Behavior, 47, 1165–1173.
Hansen, S., Harthon, C., Wallin, E., Löfberg, L., & Svensson, K. (1991a). The effects of 6-OHDA-induced dopamine depletions in the ventral or dorsal striatum on maternal and sexual behavior in the female rat. Pharmacology, Biochemistry & Behavior, 39, 71–77.
Hansen, S., Harthon, C., Wallin, E., Löfberg, L., & Svensson, K. (1991b). Mesotelencephalic dopamine system and reproductive behavior in the female rat: Effects of ventral tegmental 6-hydroxydopamine lesions on maternal and sexual responsiveness. Behavioral Neuroscience, 105, 588–598.
Hiroi, N., & White, N. M. (1990). The reserpine-sensitive dopamine pool mediates (+)-amphetamine-conditioned reward in the place preference paradigm. Brain Research, 510, 33–42.
Hiroi, N., & White, N. M. (1991). The amphetamine conditioned place preference: Differential involvement of dopamine receptor subtypes and two dopaminergic terminal areas. Brain Research, 552, 141–152.
Mackey, W. B., & van der Kooy, D. (1985). Neuroleptics block the positive reinforcing effects of amphetamine but not of morphine as measured by place conditioning. Pharmacology, Biochemistry & Behavior, 22, 101–106.
Malenfant, S. A., Barry, M., & Fleming, A. S. (1991). Effects of cycloheximide on the retention of olfactory learning and maternal experience effects in postpartum rats. Physiology & Behavior, 49, 289–294.
Malenfant, S. A., O’Hearn, S., & Fleming, A. S. (1991). MK801, an NMDA antagonist, blocks acquisition of a spatial task but does not block maternal experience effects. Physiology & Behavior, 49, 1129–1137.
Morgan, H. D., Fleming, A. S., & Stern, J. M. (1992). Somatosensory control of the onset and retention of maternal responsiveness in primiparous Sprague-Dawley rats. Physiology & Behavior, 51, 549–555.
Numan, M. (1988). Maternal behavior. In E. Knobil & J. Neill (Eds.), Physiology of reproduction (Vol. 2, pp. 1569–1646). New York: Raven Press.
Orpen, B. G., & Fleming, A. S. (1987). Experience with pups sustains maternal responding in postpartum rats. Physiology & Behavior, 40, 47–54.
Stern, J. M., & Johnson, S. K. (1990). Ventral somatosensory determinants of nursing behavior in Norway rats: I. Effects of variations in the quality and quantity of pup stimuli. Physiology & Behavior, 47, 993–1011.
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This research was supported by an N.S.E.R.C. operating grant to A.S.F.
Many thanks to Lisa Cauchi for her help with the manuscript, to Jane Magnusson for her excellent lab work, to Derek van de Kooy for his helpful comments and ideas, and to John Hyttel of H. Lundbeck & Co., Denmark, for kindly providing us with cis(Z)-flupentixol.
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Fleming, A.S., Korsmit, M. & Deller, M. Rat pups are potent reinforcers to the maternal animal: Effects of experience, parity, hormones, and dopamine function. Psychobiology 22, 44–53 (1994). https://doi.org/10.3758/BF03327079
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DOI: https://doi.org/10.3758/BF03327079