ACUTE COLD STRESS LEADING TO ELEVATED CORTICOSTERONE NEITHER ENHANCESSYNAPTIC EFFICACY NOR IMPAIRS LTP IN THE DENTATE GYRUS OF FREELY MOVING RATS

Citation
Cr. Bramham et al., ACUTE COLD STRESS LEADING TO ELEVATED CORTICOSTERONE NEITHER ENHANCESSYNAPTIC EFFICACY NOR IMPAIRS LTP IN THE DENTATE GYRUS OF FREELY MOVING RATS, Brain research, 789(2), 1998, pp. 245-255
Citations number
54
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
Volume
789
Issue
2
Year of publication
1998
Pages
245 - 255
Database
ISI
SICI code
Abstract
Exposure to stress has previously been found to impair long-term poten tiation (LTP) in the hippocampus. Exposure to Stress has also been pro posed to induce an LTP-like effect. We examined the effect of acute co ld stress on synaptic transmission, neuronal excitability, and LTP ind uction in the medial perforant path-granule cell synapse of freely mov ing rats. After obtaining baseline recordings of evoked field potentia ls at room temperature (23 degrees C), rats were transferred to an env ironmental cage maintained at 4 degrees C (cold group) or 23 degrees C (control group) and, 90 min later, high-frequency stimulation (HFS) w as applied to the medial perforant path. Serum corticosterone measured in trunk blood from rats without implanted electrodes was significant ly elevated in cold exposed (28.7 mu g/dl) rats relative to control (6 .6 mu g/dl). Despite increased corticosterone levels indicative of str ess activation, cold exposed rats exhibited LTP of the fEPSP slope and population spike of similar magnitude and time course as controls. In addition, there was no stress-specific effect on the fEPSP slope or p opulation spike and no effect on paired-pulse plasticity. Surprisingly , despite extensive cage acclimation, transferring rats to the environ mental cage was associated with a reduction in population spike amplit ude and an enhancement in paired-pulse facilitation. The results show that acute cold stress leading to elevated serum corticosterone levels neither induces LTP-like increases in synaptic efficacy nor impairs t etanus-evoked LTP in the dentate gyrus of freely moving rats. Thus, im paired working memory during cold stress is not due to an inability of perforant path synapses to express LTP. (C) 1998 Elsevier Science B.V .