Non-NMDA receptors in the lateral parabrachial nucleus modulate sodium appetite.
Glutamatergic mechanisms have been implicated in the control of fluid ingestion. In the present study, we investigated whether non-N-methyl-d-aspartate (NMDA) glutamatergic receptors in the lateral parabrachial nucleus (LPBN) are involved in the control of water and sodium intake. Male Sprague-Dawley rats had cannulas implanted bilaterally into the LPBN. They were acutely depleted of water and sodium by injections of the diuretic furosemide (Furo; 10 mg/kg, bw) and given a low dose of the angiotensin-converting enzyme inhibitor, captopril (Cap; 5 mg/kg, bw). Bilateral LPBN injections of the non-NMDA receptor antagonist DNQX (2 and 5 nmol/0.2 microl) increased the ingestion of 0.3 M NaCl and water of Furo/Cap treated rats. The increased ingestion produced by DNQX was abolished by pretreating the LPBN with alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), a non-NMDA receptor agonist. AMPA injected alone into the LPBN reduced water and 0.3 M NaCl intake. Injections of DNQX (5 nmol/0.2 microl) into the LPBN also produced ingestion of 0.3 M NaCl after sc injections of the beta-adrenoceptor agonist, isoproterenol, a hypotensive drug that typically produces only water intake. Food intake, arterial blood pressure and heart rate were not altered by DNQX LPBN injections. We conclude that agonists acting on non-NMDA receptors in the LPBN exert an inhibitory influence on sodium intake during acute fluid depletion with hypotension and after isoproterenol treatment. A possible interaction of serotonin with glutamate within the LPBN is discussed.
De Gobbi
Juliana I F
JI
Department of Psychology, Cardiovascular Center, University of Iowa, Iowa City, 52242-1407, USA.
Beltz
Terry G
TG
Johnson
Ralph F
RF
Menani
José Vanderlei
JV
Thunhorst
Robert L
RL
Johnson
Alan Kim
AK
D000704:Analysis of Variance; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D002216:Captopril / Q000494:pharmacology; D002408:Catheters, Indwelling; D004232:Diuretics / Q000494:pharmacology; D004326:Drinking / Q000187:drug effects* / Q000502:physiology; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D007022:Hypotension / Q000139:chemically induced; D008297:Male; D011149:Pons / Q000187:drug effects / Q000378:metabolism*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism*; D012982:Sodium, Dietary; D013997:Time Factors; D014868:Water Deprivation; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D000959:Antihypertensive Agents; D004232:Diuretics; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D018091:Receptors, AMPA; D012982:Sodium, Dietary; C056723:FG 9041; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D005665:Furosemide; D002216:Captopril