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Male and female rats form a conditioned preference to copulate and/or mate with conspecifics bearing an odor that was paired with either the postejaculatory reward state in males, or paced sexual contact in females, making the odor act as a discrete partner-related cue. Here, we asked whether a somatosensory cue, a rodent jacket, could act as a discrete cue to establish a conditioned partner choice (CPC). In the first study, sexually naïve Long-Evans males and females underwent 14 copulatory conditioning trials for 30 min with their opposite sex partner in unilevel pacing chambers. On the final test, each experimental male or female was placed into an open field with two sexually receptive partners, one jacketed and the other unjacketed. A trend was found for more males to ejaculate first with jacketed females relative to the unjacketed females, whereas the females had no preference. Males and females in the second study were exposed sequentially to jacketed, sexually receptive partners, and unjacketed, sexually nonreceptive partners prior to a final open field test. Both males and females displayed a significant CPC for the jacketed opposite sex partner. This study demonstrates that a somatosensory cue previously used to establish sexual arousal as a contextual cue on rats can be used as a discrete, partner-based cue to establish a CPC for a particular partner wearing the jacket and that stronger conditioning occurs when the jacket is explicitly paired with the sexual reward state. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Male rats develop a conditioned ejaculatory preference (CEP) toward females bearing an odor or somatosensory cue (rodent jacket) when those stimuli are paired with the postejaculatory reward state. As with a copulatory conditioned place preference, CEP for an odor depends on endogenous opioid transmission after ejaculation. The nonselective opioid receptor antagonist naloxone (NAL) disrupts CEP for an odor cue on female rats when injected systemically to males prior to each conditioning trial. Here, we evaluated whether NAL would disrupt the development of a CEP for the somatosensory cue. Long-Evans males were assigned randomly to two groups and underwent 14 copulatory conditioning trials for 30 min each, spaced every 4 days, and consisting of sequential pairing of a jacket on a sexually receptive female and no jacket on a sexually nonreceptive female. The control group was injected with saline (SAL) in both conditions throughout training, whereas the experimental group was injected with NAL when females were receptive and wore a jacket, and with SAL when they were not receptive and did not wear a jacket. On the final test, all males were injected with SAL and placed into an open field with two sexually receptive females, one with the jacket and the other without the jacket. Control males displayed a significant CEP for females with the jacket on, whereas males injected with NAL during sexually receptive jacket conditions displayed a significant CEP for the nonjacketed female. This study confirms that opioid transmission is necessary for the establishment of a somatosensory CEP. (PsycINFO Database Record (c) 2019 APA, all rights reserved).