Abstract
In vitro incubation of mononuclear leukocytes (MNL) with catecholamines desensitizes beta adrenergic receptors, meaning isoproterenol-stimulated cyclic AMP accumulation decreases. This desensitization is accompanied by two patterns of receptor changes: first, reduction of surface receptors (defined as binding of [3H]dihydroalprenolol inhibited by 1 μM CGP 12177 [4-(3-tertiarybutylamino-2-hydroxypropoxy)-benzimidazole-2-on- hydrochloride]) without any change in the total number of [3H] dihydroalprenolol binding sites inhibited by 1 μM propranolol (receptor redistribution); then reduction of the total number of receptors (receptor down-regulation). In the present study we investigated receptor redistribution and down-regulation under physiological conditions by raising endogenous catecholamines in the rat by stress. In young rats a single immobilization stress induced MNL beta adrenergic receptor redistribution: the number of surface receptors was reduced by about 50% but the total number remained the same. Receptor redistribution was prevented completely in rats pretreated with beta-blocking nadolol. Repeated stress down-regulation the MNL beta adrenergic receptors as shown by a reduction in the total number of sites. We also investigated the regulation of beta adrenergic receptors in three age-groups. After 60 min of immobilization stress the number of MNL surface receptors was reduced in young (4-month-old) rats but not in mature (12-month-old) or aged (26-month-old) rats. Using an alternative stress procedure, after single or repeated open-field sessions, we found receptor redistribution and down-regulation, respectively, in young rats. None of these adaptive receptor response was observed in 26-month-old rats. We conclude that beta adrenergic receptor redistribution and down-regulation can occur under physiological conditions and that these adaptive receptor changes are impaired with aging.
| Original language | English |
|---|---|
| Pages (from-to) | 228-233 |
| Number of pages | 6 |
| Journal | Journal of Pharmacology and Experimental Therapeutics |
| Volume | 240 |
| Issue number | 1 |
| Publication status | Published - 1987 |
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Regulation of beta adrenergic receptors on rat mononuclear leukocytes by stress : Receptor redistribution and down-regulation are altered with aging. / De Blasi, A.; Fratelli, M.; Wielosz, M.; Lipartiti, M.
In: Journal of Pharmacology and Experimental Therapeutics, Vol. 240, No. 1, 1987, p. 228-233.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Regulation of beta adrenergic receptors on rat mononuclear leukocytes by stress
T2 - Receptor redistribution and down-regulation are altered with aging
AU - De Blasi, A.
AU - Fratelli, M.
AU - Wielosz, M.
AU - Lipartiti, M.
PY - 1987
Y1 - 1987
N2 - In vitro incubation of mononuclear leukocytes (MNL) with catecholamines desensitizes beta adrenergic receptors, meaning isoproterenol-stimulated cyclic AMP accumulation decreases. This desensitization is accompanied by two patterns of receptor changes: first, reduction of surface receptors (defined as binding of [3H]dihydroalprenolol inhibited by 1 μM CGP 12177 [4-(3-tertiarybutylamino-2-hydroxypropoxy)-benzimidazole-2-on- hydrochloride]) without any change in the total number of [3H] dihydroalprenolol binding sites inhibited by 1 μM propranolol (receptor redistribution); then reduction of the total number of receptors (receptor down-regulation). In the present study we investigated receptor redistribution and down-regulation under physiological conditions by raising endogenous catecholamines in the rat by stress. In young rats a single immobilization stress induced MNL beta adrenergic receptor redistribution: the number of surface receptors was reduced by about 50% but the total number remained the same. Receptor redistribution was prevented completely in rats pretreated with beta-blocking nadolol. Repeated stress down-regulation the MNL beta adrenergic receptors as shown by a reduction in the total number of sites. We also investigated the regulation of beta adrenergic receptors in three age-groups. After 60 min of immobilization stress the number of MNL surface receptors was reduced in young (4-month-old) rats but not in mature (12-month-old) or aged (26-month-old) rats. Using an alternative stress procedure, after single or repeated open-field sessions, we found receptor redistribution and down-regulation, respectively, in young rats. None of these adaptive receptor response was observed in 26-month-old rats. We conclude that beta adrenergic receptor redistribution and down-regulation can occur under physiological conditions and that these adaptive receptor changes are impaired with aging.
AB - In vitro incubation of mononuclear leukocytes (MNL) with catecholamines desensitizes beta adrenergic receptors, meaning isoproterenol-stimulated cyclic AMP accumulation decreases. This desensitization is accompanied by two patterns of receptor changes: first, reduction of surface receptors (defined as binding of [3H]dihydroalprenolol inhibited by 1 μM CGP 12177 [4-(3-tertiarybutylamino-2-hydroxypropoxy)-benzimidazole-2-on- hydrochloride]) without any change in the total number of [3H] dihydroalprenolol binding sites inhibited by 1 μM propranolol (receptor redistribution); then reduction of the total number of receptors (receptor down-regulation). In the present study we investigated receptor redistribution and down-regulation under physiological conditions by raising endogenous catecholamines in the rat by stress. In young rats a single immobilization stress induced MNL beta adrenergic receptor redistribution: the number of surface receptors was reduced by about 50% but the total number remained the same. Receptor redistribution was prevented completely in rats pretreated with beta-blocking nadolol. Repeated stress down-regulation the MNL beta adrenergic receptors as shown by a reduction in the total number of sites. We also investigated the regulation of beta adrenergic receptors in three age-groups. After 60 min of immobilization stress the number of MNL surface receptors was reduced in young (4-month-old) rats but not in mature (12-month-old) or aged (26-month-old) rats. Using an alternative stress procedure, after single or repeated open-field sessions, we found receptor redistribution and down-regulation, respectively, in young rats. None of these adaptive receptor response was observed in 26-month-old rats. We conclude that beta adrenergic receptor redistribution and down-regulation can occur under physiological conditions and that these adaptive receptor changes are impaired with aging.
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M3 - Article
C2 - 3027304
AN - SCOPUS:0023121845
VL - 240
SP - 228
EP - 233
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
SN - 0022-3565
IS - 1
ER -