Influence of age on the thyroid hormone-induced up-regulation of beta-adrenoceptors in mouse brain cortex.
The influence of ageing on the ability of the brain cortex beta-adrenoceptors to be regulated by very short stimulation with thyroid hormones has been investigated. Experiments were performed in 3-, 10-, 17- and 22-month-old mice using both thyroxine (T4) and triiodothyronine (T3) as stimulators and analyzing beta-adrenergic receptor characteristics 15 and 60 min after hormone injection. Results showed that a statistically significant up-regulation is present in both young and old mice when treated with T3. On the contrary, after T4 injection only 3-month-old animals respond to such a short-term treatment, whereas older adult and old animals showed not statistically significant changes. Thus, the impairment in the T4-induced up-regulation starts already in adult mice and does not seem to further increase progressively with advancing age. From these findings it is suggested that the lack of responsiveness of beta-adrenoceptors to T4 but not to T3 stimulation in adult and old mice may be due to relatively early impairment in the transformation of T4 into T3.
Viticchi
C
C
Centre of Biochemistry, Gerontological Research Department, INRCA, Ancona, Italy.
Grinta
R
R
Piantanelli
L
L
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002540:Cerebral Cortex / Q000737:chemistry*; D051379:Mice; D008807:Mice, Inbred BALB C; D011943:Receptors, Adrenergic, beta / Q000737:chemistry / Q000187:drug effects*; D013974:Thyroxine / Q000494:pharmacology*; D014284:Triiodothyronine / Q000494:pharmacology*
D011943:Receptors, Adrenergic, beta; D014284:Triiodothyronine; D013974:Thyroxine