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This Article Full Text Full Text (PDF) All Versions of this Article: 296/2/H325    most recent 01044.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nakamura, T. Articles by Sapru, H. N. Search for Related Content PubMed PubMed Citation Articles by Nakamura, T. Articles by Sapru, H. N.

Cardiovascular responses to microinjections of urocortin 3 into the nucleus tractus solitarius of the rat

Department of Neurological Surgery, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey

Submitted 30 September 2008 ; accepted in final form 27 November 2008

Urocortin 3 (Ucn3) is a new member of the corticotropin-releasing factor (CRF) peptide family and is considered to be a specific and endogenous ligand for CRF type 2 receptors (CRF₂Rs). The presence of CRF₂Rs has been reported in the nucleus tractus solitarius (NTS) of the rat. It was hypothesized that the activation of CRF₂Rs in the medial NTS (mNTS) may play a role in cardiovascular regulation. This hypothesis was tested in urethane-anesthetized, artificially ventilated, adult male Wistar rats. Microinjections (100 nl) of Ucn3 (0.03, 0.06, 0.12, and 0.25 mM) into the mNTS of anesthetized rats elicited decreases in mean arterial pressure (MAP: 5.0 ± 1.0, 21.6 ± 2.6, 20.0 ± 2.8, and 12.7 ± 3.4 mmHg, respectively) and heart rate (HR: 7.8 ± 2.6, 46.2 ± 9.3, 34.5 ± 8.4, and 16.6 ± 4.9 beats/min, respectively). Microinjections of artificial cerebrospinal fluid (100 nl) into the mNTS did not elicit cardiovascular responses. Maximum decreases in MAP and HR were elicited by 0.06 mM concentration of Ucn3. Cardiovascular responses to Ucn3 were similar in unanesthetized midcollicular decerebrate rats. A bilateral vagotomy completely abolished Ucn3-induced bradycardia. The decreases in MAP and HR elicited by Ucn3 (0.06 mM) were completely blocked by astressin (1 mM; nonselective CRFR antagonist) and K41498 (5 mM; selective CRF₂R antagonist). Microinjections of Ucn3 (0.06 mM) into the mNTS decreased the efferent greater splanchnic nerve activity. After the blockade of CRF₂Rs in the mNTS, a Ucn3-induced decrease in the efferent sympathetic nerve discharge was abolished. These results indicate that Ucn3 microinjections into the mNTS exerted excitatory effects on the mNTS neurons via CRF₂Rs, leading to depressor and bradycardic responses.

blood pressure; corticotropin-releasing factor receptor antagonists; heart rate; sympathetic nerve activity; urocortin; nucleus tractus solitarius

This article has been cited by other articles:

				T. Nakamura and H. N. Sapru Cardiovascular responses to microinjections of urocortins into the NTS: role of inotropic glutamate receptors Am J Physiol Heart Circ Physiol, June 1, 2009; 296(6): H2022 - H2029. [Abstract] [Full Text] [PDF]