Alterations in spleen norepinephrine and lymphocyte [3H]dihydroalprenolol binding site number in genetically epilepsy-prone rats.
Noradrenergic neurotransmission plays an important role in normal immune reactivity. Genetically epilepsy-prone (GEPR-9) rats exhibit deficits in central noradrenergic systems and diminished plaque-forming cell responses following immunization in vivo. In the present study we examined the hypothesis that immunosuppression in GEPR-9 rats is associated with alterations in the splenic noradrenergic system. The content of norepinephrine (NE) in spleens of GEPR-9 age-matched nonepileptic Sprague-Dawley control rats was determined by high-performance liquid chromatography coupled with electrochemical detection (HPLC-EC). In addition, we measured the number of beta-adrenergic receptors on splenic lymphocyte membranes of GEPR-9 and control rats using the beta-adrenergic receptor antagonist dihydroalprenolol ([3H]DHA). HPLC-EC analysis revealed that splenic norepinephrine content was significantly greater in GEPR-9 rats than in controls. Results from receptor binding studies indicated a 33% reduction in specific binding of [3H]DHA to splenic lymphocyte membranes of GEPR-9 rats. Saturation of binding studies revealed a significant decrease in the maximum number of [3H]DHA binding sites on splenic lymphocyte membranes from GEPR-9 rats. These results indicate that the noradrenergic system in GEPR-9 rat spleen is altered. Whether either or both of these changes contribute to reduced immune reactivity in GEPR-9 rats remains to be determined.
Department of Anatomy, University of New Mexico, School of Medicine, Albuquerque 87131.
J A
JA
Carr
K A
KA
Ortiz
L L
LL
Paxton
L C
LC
Saland
D D
DD
Savage
D000818:Animals; D004082:Dihydroalprenolol / Q000378:metabolism*; D004827:Epilepsy / Q000235:genetics / Q000378:metabolism*; D007958:Leukocyte Count; D008214:Lymphocytes / Q000737:chemistry*; D008954:Models, Biological; D009638:Norepinephrine / Q000032:analysis*; D009929:Organ Size; D051381:Rats; D011922:Rats, Mutant Strains / Q000235:genetics / Q000378:metabolism*; D017207:Rats, Sprague-Dawley / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D013154:Spleen / Q000737:chemistry* / Q000473:pathology
D011943:Receptors, Adrenergic, beta; C028413:dihydroalprenolol receptor; D004082:Dihydroalprenolol; D009638:Norepinephrine