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Effect of Stress and ACTH on Blood Pressure, Heart Rate and Locomotion in Rats: Telemetric Measurements
Author(s) -
Sabban Esther Louise,
Schilt Nina,
Serova Lidia,
Masineni Sreeharsha,
Stier Charles T
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a880-b
Activation of the hypothalamic pituitary adrenal axis and sympathoadrenal catecholaminergic systems play key roles in blood pressure regulation and the response to stress. To examine the cardiovascular responses to acute and repeated immobilization stress (IMO) and ACTH injections in male Sprague Dawley (SD) rats, radiotelemetry probes were implanted in the aorta. Systolic and diastolic blood pressure (BP), heart rate (HR) and locomotive activity were monitored every 5 min during 12h:12h light‐dark cycle. Eight days after surgery, animals were exposed to 2 h IMO (10AM to noon), or injected sc with ACTH 13 U/kg or saline, daily for 6 days. The first exposure to ACTH or IMO elevated BP to similar levels by about 30 mmHg, but the effect of ACTH was short lived. IMO triggered a large and sustained elevation of HR, whereas HR decreased after ACTH. The largest effect was observed on the first day of IMO. Responses on 2nd to 6th day of IMO were similar. The responses to ACTH were also greatest on the first day but became similar to saline control upon repeated injections. Exposure to IMO, but not ACTH, triggered a large reduction of locomotive activity during the dark (normally active phase) to levels similar to light phase. Activity returned very gradually and did not attain normal levels even several days after termination of the 6 days of IMO. The results show that there are prolonged alterations in cardiovascular regulation and locomotion following repeated stress which may mediate increased allostatic load and susceptibility to stress‐related disorders. (Supported by NIH NS44218)