Progesterone modifies the responsivity of the amygdala-mPFC connection in male but not female Wistar rats

• Published in: Neuroscience letters 2017-05, Vol.649, p.1-6
• Main Authors: Contreras, Carlos M., Gutiérrez-García, Ana G.
• Format: Article
• Language: English
• Subjects: Animals; Basal amygdala; Basolateral Nuclear Complex - physiology; Electric Stimulation; Female; Infralimbic cortex; Male; Medial prefrontal cortex; Neural Pathways - physiology; Neurons - physiology; Prefrontal Cortex - physiology; Prelimbic cortex; Progesterone; Progesterone - administration & dosage; Progesterone - physiology; Rats, Wistar; Sex Characteristics; Sex differences
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2017.04.002

•Basal amygdala stimulation produced a brief excitatory response in PL and IL neurons, followed by a long-lasting inhibitory response.•The highest inhibitory response of the BA-mPFC occurred in the PL region in males.•Progesterone reduced the response in the PL region in males, with an opposite response in females.•Progesterone reduced the responsivity of the PL and IL to BA stimulation only in males.•Progesterone negated the sex difference in the responsivity of the BA-PL connection. Amygdala-medial prefrontal cortex (mPFC) connections partially regulate fear, anxiety, and the acquisition of conditioned fear. Progesterone exerts some effects on anxiety and fear. Currently unknown, however, are the actions of progesterone on the responsivity of amygdala-mPFC connections and possible sex differences. We performed single-unit extracellular recordings from the prelimbic (PL) and infralimbic (IL) cortices of the mPFC during stimulation of the basal amygdala (BA) in anesthetized male and diestrus female rats. Basal amygdala stimulation produced an initial excitatory paucisynaptic response that was similar between sexes and unaffected by progesterone. A long-lasting inhibitory response followed the initial brief excitatory response, which was more pronounced in the PL region in males. The unit activity ratio analysis indicated that progesterone negated the sex difference in the PL region response to BA stimulation. The results suggest that progesterone decreases the responsivity to amygdala stimulation, particularly in males compared with diestrus females, which may be related to sex differences in the strategies to cope with threatening situations.