Noradrenergic enhancement of object recognition and object location memory in mice

Figures & data

Figure 1. Posttraining administration of the noradrenergic stimulant yohimbine dose-dependently enhances consolidation of object recognition memory. Data are shown as mean ± SEM. (A) Experimental design of the object recognition memory (ORM) task. Mice were trained for 3 min followed immediately by a subcutaneous injection of yohimbine (YOH, 0.3 or 1.0 mg/kg) or saline. Object recognition memory was tested 24 h later during which one of the objects was replaced by a novel object. (B) The higher dose of yohimbine improved memory performance on the object recognition retention test compared to saline-treated animals. (C) Yohimbine treatment did not affect total exploration time of the two objects during the retention test. (D) Yohimbine treatment did not affect the total distance moved during the retention test. saline: n = 14, YOH 0.3 mg/kg: n = 14, YOH 1.0 mg/kg: n = 13. ◆ p < .05, main effect of drug administration; ## p < .01, difference from saline; ** p < .01, difference from chance level.

Figure 2. Posttraining administration of the noradrenergic stimulant yohimbine dose-dependently enhances the consolidation of object location memory. Data are shown as mean ± SEM. (A) Experimental design of the object location memory (OLM) task. Mice were trained for 3 min followed immediately by a subcutaneous injection of yohimbine (YOH, 0.3 or 1.0 mg/kg) or saline. Object location memory was tested 24 h later during which one of the objects was relocated to a novel location. (B) Both the higher and lower dose of yohimbine improved memory performance on the object location retention test compared to saline. (C) Yohimbine treatment did not affect total exploration time of the two objects during the retention test. (D) Yohimbine treatment did not affect the total distance moved during the retention test. saline: n = 10, YOH 0.3 mg/kg: n = 8, YOH 1.0 mg/kg: n = 11. ◆◆ p < .01, main effect of drug administration; ## p < .01, difference from saline; ** p < .01,*** p < .001, difference from chance level.

Table 1. Training data of object recognition memory (ORM) and object location memory (OLM).

Task	Training data items	Saline	YOH 0.3 mg/kg	YOH 1.0 mg/kg
ORM	Object exploration time (s)	10.9 ± 0.8	11.8 ± 0.9	12.5 ± 1.0
	Total distance moved (m)	6.4 ± 0.5	8.2 ± 0.7	8.3 ± 0.6
OLM	Object exploration time (s)	8.4 ± 0.8	11.7 ± 1.2	10.0 ± 1.0
	Total distance moved (m)	7.8 ± 0.4	8.3 ± 0.7	9.1 ± 0.5