Academic journal article International Journal of Psychology and Psychological Therapy

Visual-Olfactory Contact with a Receptive Female Reduces Anxiety in Reward Downshift and Open Field Tests in Male Rats

Academic journal article International Journal of Psychology and Psychological Therapy

Visual-Olfactory Contact with a Receptive Female Reduces Anxiety in Reward Downshift and Open Field Tests in Male Rats

Article excerpt

There is abundance of evidence showing that rats encountering a surprising downshift in reinforcement conditions sharply suppress the consumption of the devalued reward and develop an anxiety-related state that has been called frustration (Amsel, 1992; see Flaherty, 1996, for an extensive review on incentive relativity; see Papini & Dudley, 1997, for a review on surprising reward omission effects). For instance, when mammals face a downshift in the expected quality or quantity of an appetitive reinforcer (e.g. 32%-to-4% sucrose solution shift), they show a significant decrease in their consummatory performance and an increase in their ambulation and rearing behavior in comparison to control subjects that are trained with the lower reinforcer (Flaherty, 1996). This phenomenon has been called "consummatory Successive Negative Contrast" (SNC) effect. Moreover, rats unexpectedly shifted from a 32% sucrose solution to a less-preferred 4% solution presented a faster recovery in consumption of the devalued reinforcer when they had been administered anxiolytic drugs, such as diazepam, before the second post-shift session of a Successive Negative Contrast (SNC) relative to control animals (Flaherty, 1996).

Freidin, Kamenetzky, and Mustaca (2005) showed that the anxiolytic effect upon cSNC could be reproduced if rats were allowed to ejaculate twice before the second post-shift sessions relative to control males not exposed to females. Moreover, Fernández Guasti, Roldán Roldán, and Saldívar (1989) found a reduction in burying behavior towards a source of noxious stimulation in males that had ejaculated before the test when compared with either controls unexposed to females or animals allowed to copulate for five intromissions only. Both groups of authors (i.e., Fernández Guasti et al., 1989, and Freidin et al., 2005) concluded that ejaculation seemed to have anxiolytic-like effects.

Though the conclusion of an anxiolytic-like effect of ejaculation had some support on the burying behavior test where males that had copulated for 5 intromissions behaved similarly to controls and differently from ejaculators (Fernández Guasti et al., 1989), the control group where males were socio-sexually stimulated but did not ejaculate was missing when testing ejaculation effects on reward downshift situations (Freidin et al., 2005).

The goal of the present study was to test whether ejaculation was a necessary factor to produce an anxiolytic-like effect as tested in a reward downshift situation and in an open field test. In Experiment 1, male rats were tested in the second post-shift session of a sucrose solution downshift situation after having the chance of an ejaculation, visual and olfactory contact with a receptive female, or no contact with females before the test. This experiment aimed to compare only the consumption rate (goal-tracking time) after experiencing a reward downshift in animals that experienced different socio-sexual conditions and thus, did not require assessing differences between downshifted and unshifted subjects. In Experiment 2, the same treatments were applied before males were placed in an open field for 5 min. This second experiment allowed us to test anxiety responses (as evidenced by exploration of central areas of the apparatus) in a different procedure, and also let us control for general activity as evidenced by total locomotor activity.

Experiment 1

The goal of the present experiment was to explore whether socio-sexual stimulation is a sufficient factor to obtain an anxiolytic-like effect in a surprising reward reduction situation. With this goal in mind, we assigned males to three independent treatments (i.e., ejaculation, visual-olfactory contact with a receptive female, and controls not exposed to females) that were applied before the second post-shift session of a 32%-to-4% sucrose downshift procedure. According to results obtained in burying behavior tests (Fernández Guasti et al. …

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