Ventral and Dorsal Hippocampus of rats similarly modulate autonomic responses evoked by restraint stress

Abstract

IntroductionThe hippocampus is a brain structure divided into dorsal (DH) and ventral (VH) portions. Stimulation of these areas evokes autonomic changes. During restrain stress (RS) hippocampus neurons are activated, besides causing hormonal changes and autonomic responses such as increased heart rate (HR) mean arterial pressure (MAP) and reduction of tail temperature. Thus, the aim of our study was to investigate the involvement of VH and DH on the autonomic responses, caused by the RS.MethodsMicroinjections of CoCl2 (cobalt chloride; 1mM/ 500nL) or vehicle in the VH or DH of Male Wistar were made. Ten minutes after the microinjection of drugs, the animals were submitted to the RS for an hour. During RS cardiovascular parameters and skin temperature were registered.ResultsThe injections of CoCl2 into the VH (n=6) significantly reduced the increase of both MAP (F1,480=449.5; P < 0.001) and HR (F1,480 = 429.8, P<0.0001) and temperature decreases (F1,144 = 273.2, P<0.0001) evoked by RS, when compared to the control animals (n=4). In the same way, the bilateral microinjections of CoCl2 in DH (n=7) reduced the increase of both MAP (F1,165= 211, P<0.05) and HR (F1,165= 161, P<0.05) and temperature decreases (F1,165= 164, P<0.05) when compared to the control animals (n=6).ConclusionThese results suggest that show that VH and DH similarly modulate autonomic responses to RS.Financial Support: CAPES and FAPESP.