Modulation of Mouse Brain Cortex Adrenoceptor in Old Mice by Supplementation of Zinc and Thymomodulin

• Published in: Gerontology (Basel) 1999-09, Vol.45 (5), p.265-268
• Main Authors: Viticchi, Claudio, Moresi, Raffaella, Piantanelli, Lucio
• Format: Article
• Language: English
• Subjects: Aging - metabolism; Animals; Binding, Competitive - drug effects; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cerebral Cortex - drug effects; Cerebral Cortex - metabolism; Experimental Section; Fundamental and applied biological sciences. Psychology; Injections, Intraperitoneal; Male; Membranes - drug effects; Membranes - metabolism; Mice; Mice, Inbred BALB C; Radioligand Assay; Receptors, Adrenergic - metabolism; Receptors, Adrenergic, alpha - metabolism; Receptors, Adrenergic, beta - metabolism; Thymus Extracts - pharmacology; Up-Regulation; Vertebrates: nervous system and sense organs; Zinc - pharmacology
• ISSN: 0304-324X; 1423-0003
• DOI: 10.1159/000022099

Background: Previous experiments have shown that the age-related decrease of mouse brain cortex adrenoceptor density can be recovered by grafting a neonatal thymus into old recipients. The question arises whether similar results can also be obtained in the presence of a single thymic factor such as thymomodulin (TMD). It is worth noting that the activity of some thymic factors is strictly zinc (Zn) dependent and that their age-related decreased production is recovered in old mice supplemented with Zn. Objective: The above-mentioned evidences prompted us to verify whether Zn and TMD, either alone or combined, are able to induce some corrective effects on age-dependent alterations of adrenoceptor characteristics of the mouse brain cortex. Methods: Thus, we performed experiments on four groups of Balb/c mice treated with saline, Zn, TMD, or both Zn and TMD. Treatments started when animals were 18 months old and ran for 6 months. The α 1 - and β-Adrenoceptor characteristics were assayed by steady state binding analysis using labelled prazosine and iodocyanopindolol, respectively. Data were analyzed using one-way analysis of variance, followed, when appropriate, by multiple-comparison analysis. Results: Results show an increase of β-adrenoceptor density and a decrease of α 1 -adrenoceptor density in both Zn- and Zn+TMD-treated animals when compared to saline-treated controls, while receptor affinities did not change significantly. Conclusions: The lack of action of TMD suggests that this type of treatment cannot mimic the effects of grafting the whole gland; it cannot be excluded that different time-dose schedule could be more effective. Zn treatment, on the other hand, does modulate adrenoceptors; however, it shows a corrective action on the age-related decreased density of β-adrenoceptors, but further decreases that of α 1 -adrenoceptors. This differential action could be due to their differential physiological role.