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Abstract: The present study was aimed to determine whether the urine from donor rats, which were physically stressed (UD-PS) by unavoidable electric footshocks, produces despair in receptor partner rats (RP) in the long-term. For each trial, an RP rat was placed during 10 min once per day for 21 days in a small non-movement-restricting cage impregnated with the urine collected from a UD-PS rat. Control rats, free of stimulation, maintained their locomotion and immobility scores at basal values throughout the 21-day test. After 21 days of stressing experience [F(2,90)=15.22, P <0.0001] locomotion significantly increased in RP rats (r =0.938, P <0.01), whereas in the UD-PS group locomotion decreased (r =−0.606, P <0.05). The RP and UD-PS groups displayed the longest time of immobility [F(2,90)=8.83, P <0.001] in the forced-swim test (RP, r =0.886, P <0.05; UD-PS, r =0.962, P <0.001) compared with the control group (r =−0.307, NS). We conclude that the RP became similarly despaired as the UD-PS group through the action of 2-heptanone, a ketonic compound identified in UD-PS urine by HS-GC/MS techniques. This ketone was found to be increased [F(2,15)=3.50, P <0.05] from the 1st day of unavoidable electric footshocks, and to induce despair, an effect reverted [F(2,21)=16.5, P <0.0001] by imipramine (5.0 mg/kg) in another group of rats. [Copyright &y& Elsevier]

Abstract: The sensorial stimulation arising from a physically stressed (PS) subject may produce emotional stress in a witnessing partner (WP). Both members of the pair develop functional changes. We tested changes in locomotor activity (crossing) and in the defensive burying test in WP, and PS adult male Wistar rats having been submitted to a single 10min session in a two-compartment cage. During this session, the WP rats received auditory and olfactory stimulation coming from a PS pair submitted to unavoidable electric footshocks (1mA, dc, 0.5s, 0.5c/s, 10min). This experiment was replicated in other groups pre-treated with vehicle or diazepam, and their urine was collected and analyzed by the static Head-Space and Gas Chromatography–Mass Spectrometry (HS-GC/MS) techniques. The WP group displayed a significantly higher crossing [F (2,45) =4.31, P <0.01] and more cumulative burying time [F (2,22) =4.73, P <0.01] than the control or PS groups. Diazepam (1mg/kg) reverted these changes. Our results indicate that the conspecific sensorial communication coming from the PS group produces anxiety probably mediated by 2-heptanone, since the HS-GC/MS analyses showed the highest amount of 2-heptanone in the urine from the PS group [F (2,42) =5.17, P <0.009]. [Copyright &y& Elsevier]