Hypothalamic sites mediating cardiovascular effects of microinjected bicuculline and EAAs in rats.

Abstract

Microinjection of gamma-aminobutyric acidA receptor antagonist bicuculline methiodide (BMI) into either the dorsomedial hypothalamic nucleus (DMH) or the nearby paraventricular hypothalamic nucleus (PVN) has been reported to evoke marked tachycardia and modest pressor effects. We compared the effects of microinjecting BMI and excitatory amino acids (EAAs) into 1) the DMH, 2) the PVN, and 3) an intermediate area between the two nuclei. In conscious rats, microinjection of (in pmol) 10 BMI, 0.5 kainic acid, or 5 N-methyl-D-aspartate into the DMH markedly increased heart rate and slightly elevated arterial pressure, whereas injections into other regions provoked changes that progressively declined in magnitude with increasing distance from the nucleus. A similar pattern was evident in urethan-anesthetized rats, where the shortest latency to onset of BMI-induced increases in heart rate was seen after injection into the DMH. These findings demonstrate that the cardiovascular changes seen after microinjection of BMI or EAAs into the medial hypothalamus result from an action in the DMH and not from spread to the PVN.

• Authors: V De Novellis, E H Stotz-Potter, S M Morin, F Rossi, J A DiMicco
• Journal: The American journal of physiology (Am J Physiol) Vol. 269 Issue 1 Pt 2 Pg. R131-40 (Jul 1995) ISSN: 0002-9513 [Print] United States
• PMID: 7631885 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Excitatory Amino Acids
• Aspartic Acid
• Kainic Acid
• Bicuculline

Topics

• Anesthesia
• Animals
• Aspartic Acid (pharmacology)
• Bicuculline (pharmacology)
• Cardiovascular System (drug effects)
• Excitatory Amino Acids (pharmacology)
• Hypothalamus (physiology)
• Kainic Acid (pharmacology)
• Male
• Microinjections
• Rats
• Rats, Sprague-Dawley