Changes of [3H]spiroperidol binding in the renal artery of aged rabbits.

Dipartimento di Scienze Neurologiche-Univesità “La Sapienza”, Via A. Borelli 50, 00161 Roma Italy; Istituto di Patologia Generale, Università di Messina, Via A. Castelli, 90100 Messina Italy
Mechanisms of Ageing and Development (Impact Factor: 3.26). 12/1984; 28(1):41-5. DOI: 10.1016/0047-6374(84)90151-9
Source: PubMed

ABSTRACT Using mature (12 months), old (70 months) rabbits and 3H-labeled spiroperidol, the characteristics of renal artery dopamine receptors were studied. In old age the dissociation constant of [3H]spiroperidol was unchanged, while maximum specific binding was reduced more than 45%. The present data seem to indicate an impairment of peripheral dopaminergic function in ageing.

  • [Show abstract] [Hide abstract]
    ABSTRACT: 1. The pharmacological characteristics and the anatomical localization of dopamine (DA) DA-1 and DA-2 receptor sites were analysed in sections of rat heart, kidney, cerebral, mesenteric and caudal arteries. Moreover, DA-1 receptors were characterized in sections of human kidney. 2. [3H]-SCH 23390, used as a ligand of DA-1 receptors, was specifically bound to sections of cerebral and mesenteric arteries and to both rat and human kidney. Negligible amounts of specific binding were noticeable in the heart and in the caudal artery. The binding was consistent with the labelling of DA-1 sites. In rat tissues binding was not sensitive to 6-hydroxydopamine (6-OHDA) sympathectomy. 3. Anatomically [3H]-SCH 23390 was bound by the medial layer of cerebral, mesenteric and renal arteries. In the renal cortex, where occurred the highest accumulation of [3H]-SCH 23390 binding sites, the ligand was bound primarily by proximal convoluted cortical tubules and juxtaglomerular cells. Comparatively, the human kidney was richer in tubular binding sites than the rat kidney. The opposite is true for vascular sites. 4. [3H]-spiroperidol was used as a ligand of DA-2 receptors. To the incubation medium containing the ligand, appropriate concentrations of ketanserin were added to block the possible binding to 5-HT-2 sites. [3H]-spiroperidol was bound by sections of the structures examined in a manner consistent with the labelling of DA-2 sites. 6-OHDA caused a significant reduction in the density of cardiac and vascular [3H]-spiroperidol binding sites. 5. In the heart [3H]-spiroperidol was bound primarily by atria (6-OHDA sensitive binding).(ABSTRACT TRUNCATED AT 250 WORDS)
    Journal of Autonomic Pharmacology 02/1990; 10 Suppl 1:s11-8.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study was designed to investigate the influence of aging on noradrenaline content and the density and pattern of prejunctional dopamine D2 receptors in the tail (ventral caudal) artery of male Sprague-Dawley rats. Tail artery is frequently used as a model for investigating mechanisms of sympathetic vascular control and contains prejunctional dopamine receptor belonging to the D2 subtype. Noradrenaline levels were reduced in rats of 12 months of age in comparison with 3-month-old animals. A further reduction in catecholamine concentration was found in 24-month-old rats. The density of prejunctional D2 receptors, which was measured in frozen sections of the tail artery by using both radioligand binding and autoradiographic techniques, was reduced by about 35% in 12-month rats in comparison with 3-month rats. A decrease by about 55% versus 3-month rats and by about 20% versus 12-month rats was observed in 24-month-old rats. Neither the pharmacological profile nor the anatomical localization of prejunctional D2 receptors was changed in the rat tail artery as a function of age. The parallel decrease in noradrenaline content and in the density of prejunctional dopamine D2 receptor sites in the tail artery of Sprague-Dawley rats of different ages probably accounts for the lack of an age-related change of prejunctional dopamine D2 receptor-linked responses reported in functional studies.
    Mechanisms of Ageing and Development 09/1993; 70(1-2):83-93. · 3.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The age-related changes in the density of alpha 1-adrenoceptors in the dorsolateral lobe of the rat prostate were evaluated in Wistar rats at 8, 52, and 104 weeks of age. [3H]YM617, a newly synthesized alpha 1-adrenergic blocker, was used as the ligand. The mean maximum number of binding sites, or alpha 1-adrenoceptor density (Bmax) +/- SE of 104-week-old rats (11.0 +/- 1.2 fmol/mg protein) was significantly lower than that in the 8-week-old rats (37.0 +/- 4.3 fmol/mg protein) and 52-week-old rats (37.2 +/- 3.4 fmol/mg protein) (respectively, P < 0.01). In contrast, mean affinity (Kd) values +/- SE of these groups showed no significant differences (8-week-old rats, 115.8 +/- 9.1; 52-week-old rats, 100.5 +/- 5.8; and 104-week-old rats, 116.4 +/- 9.8 pM). Mean volumes +/- SE of muscle cells of the prostate were 3.7 +/- 1.1 x 10(3) microns3 at 8 weeks, 30.0 +/- 6.2 x 10(3) microns3 at 52 weeks, and 18.6 +/- 8.2 x 10(3) microns3 at 104 weeks. Volumes for 8-week-old rats were significantly smaller than those for 52-week-old (P < 0.01) and 104-week-old rats (P < 0.05). However, the mean area density of the muscle cells showed no difference among the three groups: 20.1 +/- 2.2% at 8 weeks, 27.3 +/- 2.9% at 52 weeks and 20.3 +/- 3.4% at 104 weeks. In conclusion, the density of YM617-binding sites (alpha 1-adrenoceptors) in 104-week-old rats was lower than in 8- and 52-week-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)
    Urological Research 01/1995; 22(6):389-92. · 1.59 Impact Factor