The effect of aging on the binding parameters of 3H-SCH 23390, the most selective ligand of D-1 DA receptors, was studied in membrane preparations from the rat retina. DA-stimulated adenylate cyclase activity was also measured in order to better characterize the changes in retinal D-1 DA receptors induced by aging. The binding studies revealed that the density of 3H-SCH 23390 was increased (34 and 73%) in the retina of 14- and 26-month-old rats, when compared to young adult animals, respectively. In contrast, aging failed to alter the sensitivity of the adenylate cyclase to the action of DA. In fact, DA (10(-6) M to 10(-4) M) elicited a similar enhancement in cyclic AMP formation in retinal homogenates of both adult and senescent rats. Since dark adaptation increases the density of D-1 DA receptors in the retina of adult rats we studied the effect of light deprivation on 3H-SCH 23390 binding and DA-sensitive adenylate cyclase activity in the retina of senescent rats. As previously shown (25) light deprivation increased 3H-SCH 23390 binding and enhanced DA-sensitive adenylate cyclase activity in the retina of young adult rats. On the contrary, dark adaptation failed to increase 3H-SCH 23390 binding and to enhance DA-sensitive adenylate cyclase activity in the retina of senescent rats. Taken together these results indicate that D-1 DA receptors in the retina of aged rats have biochemical and functional properties different from those found in the retina of adult animals; these changes may result in an altered response to the physiological stimuli elicited by environmental lighting.
Porceddu, M.L., De Montis, M.G., Pepitoni, S., Toffano, G., Biggio, G. (1990). Failure of dark adaptation to upregulate D-1 dopamine receptors in retina of senescent rats. NEUROBIOLOGY OF AGING, 11(2), 105-109 [10.1016/0197-4580(90)90042-X].
Failure of dark adaptation to upregulate D-1 dopamine receptors in retina of senescent rats
De Montis, M. G.;
1990-01-01
Abstract
The effect of aging on the binding parameters of 3H-SCH 23390, the most selective ligand of D-1 DA receptors, was studied in membrane preparations from the rat retina. DA-stimulated adenylate cyclase activity was also measured in order to better characterize the changes in retinal D-1 DA receptors induced by aging. The binding studies revealed that the density of 3H-SCH 23390 was increased (34 and 73%) in the retina of 14- and 26-month-old rats, when compared to young adult animals, respectively. In contrast, aging failed to alter the sensitivity of the adenylate cyclase to the action of DA. In fact, DA (10(-6) M to 10(-4) M) elicited a similar enhancement in cyclic AMP formation in retinal homogenates of both adult and senescent rats. Since dark adaptation increases the density of D-1 DA receptors in the retina of adult rats we studied the effect of light deprivation on 3H-SCH 23390 binding and DA-sensitive adenylate cyclase activity in the retina of senescent rats. As previously shown (25) light deprivation increased 3H-SCH 23390 binding and enhanced DA-sensitive adenylate cyclase activity in the retina of young adult rats. On the contrary, dark adaptation failed to increase 3H-SCH 23390 binding and to enhance DA-sensitive adenylate cyclase activity in the retina of senescent rats. Taken together these results indicate that D-1 DA receptors in the retina of aged rats have biochemical and functional properties different from those found in the retina of adult animals; these changes may result in an altered response to the physiological stimuli elicited by environmental lighting.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/11365/30923
Attenzione
Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo