MULTIPLE PATHWAYS FOR CRF RECEPTOR MODULATION OF SYMPATHETIC NERVOUS SYSTEM ACTIVITY
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1
Texas Tech University, Biological Sciences, United States
A hallmark of the endocrine stress response is elevated sympathetic nervous system (SNS) activity, and numerous studies have suggested a role for central CRF neurons in mediating this response. Work by our lab in an amphibian model also suggests a potential role for peripheral CRF receptors in regulating SNS activity. Here we investigate the role of peripheral CRF R1 and R2 receptors in regulating SNS activity in the cane toad Bufo marinus. Peripheral administration of oCRF significantly increased SNS activity and these effects were blocked by pretreatment with the CRF R1 antagonist NBI 27914 but not by the R2 antagonist K414988. Exposure to an interoceptive stressor increased SNS activity, an effect that was blocked by pretreatment with NBI 27914. Although CRF effects on SNS activity were not blocked by a CRF R2 antagonist, we observed that peripheral administration of CRF R2 agonists (sauvagine, UCN-1, UCN-2) increased SNS activity. In mammals, CRF R2 agonists are known to be potent vasodilators, suggesting that CRF R2 receptor activation may elevate SNS activity via baroreceptor unloading. Thus we tested whether SNS activity induced by peripheral activation of CRF R2 receptors is associated with changes in SNS and cardiovascular activity in anesthetized B. marinus. Peripheral administration of UCN-2 or the hypotensive agent sodium nitroprusside (SNP) both caused robust elevations in plasma catecholamines. As expected, SNP increased heart rate, an effect consistent with a reflexive SNS increase in response to hypotension. UCN-2 administration did cause a transient reduction in blood pressure relative to vehicle injected controls, but had no effect on heart rate. This is the first demonstration in an amphibian that activation of CRF R2 receptors lowers blood pressure, presumably through a direct vasodilatory action on vascular smooth muscle as in mammals. Collectively our data are consistent with multimodal regulation of SNS activity by CRF receptors.
Keywords:
amphibian,
Autonomic Nervous System,
stress
Conference:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology, Ann Arbor, United States, 11 Jul - 13 Jul, 2011.
Presentation Type:
Invited Symposium
Topic:
Abstracts
Citation:
Carr
JA,
Bulin
S and
Larson
R
(2011). MULTIPLE PATHWAYS FOR CRF RECEPTOR MODULATION OF SYMPATHETIC NERVOUS SYSTEM ACTIVITY.
Front. Endocrinol.
Conference Abstract:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology.
doi: 10.3389/conf.fendo.2011.03.00004
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Received:
19 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Dr. James A Carr, Texas Tech University, Biological Sciences, Lubbock, Texas, 79409-3131, United States, James.Carr@ttu.edu