Effects of chronic stress in adolescence on learned fear, anxiety, and synaptic transmission in the rat prelimbic cortex.
The prelimbic cortex and amygdala regulate the extinction of conditioned fear and anxiety, respectively. In adult rats, chronic stress affects the dendritic morphology of these brain areas, slowing extinction of learned fear and enhancing anxiety. The aim of this study was to determine whether rats subjected to chronic stress in adolescence show changes in learned fear, anxiety, and synaptic transmission in the prelimbic cortex during adulthood. Male Sprague Dawley rats were subjected to seven days of restraint stress on postnatal day forty-two (PND 42, adolescence). Afterward, the fear-conditioning paradigm was used to study conditioned fear extinction. Anxiety-like behavior was measured one day (PND 50) and twenty-one days (PND 70, adulthood) after stress using the elevated-plus maze and dark-light box tests, respectively. With another set of rats, excitatory synaptic transmission was analyzed with slices of the prelimbic cortex. Rats that had been stressed during adolescence and adulthood had higher anxiety-like behavior levels than did controls, while stress-induced slowing of learned fear extinction in adolescence was reversed during adulthood. As well, the field excitatory postsynaptic potentials of stressed adolescent rats had significantly lower amplitudes than those of controls, although the amplitudes were higher in adulthood. Our results demonstrate that short-term stress in adolescence induces strong effects on excitatory synaptic transmission in the prelimbic cortex and extinction of learned fear, where the effect of stress on anxiety is more persistent than on the extinction of learned fear. These data contribute to the understanding of stress neurobiology.
Laboratory of Behavioral Neurobiology, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
Ignacio
I
Negrón-Oyarzo
Laboratory of Behavioral Neurobiology, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile.
Miguel Ángel
MÁ
Pérez
Laboratory of Behavioral Neurobiology, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile.
Gonzalo
G
Terreros
Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
Pablo
P
Muñoz
Laboratory of Behavioral Neurobiology, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile. Electronic address: alexies.dagnino@uv.cl.
Alexies
A
Dagnino-Subiabre
D000221:Adaptation, Ocular; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000473:pathology*; D004558:Electric Stimulation; D005108:Extinction, Psychological; D005239:Fear; D005260:Female; D008297:Male; D018782:Maze Learning; D009043:Motor Activity / Q000502:physiology; D018408:Patch-Clamp Techniques; D017397:Prefrontal Cortex / Q000473:pathology* / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000473:pathology* / Q000503:physiopathology; D009435:Synaptic Transmission / Q000502:physiology*
Adolescence; Anxiety; Learned fear; Prelimbic cortex; Stress; Synaptic transmission