1993 Fiscal Year Final Research Report Summary
Postnatal alterations of mechanisms of signal transduction in rat salivary glands
| Project/Area Number |
03807123
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Functional basic dentistry
|
|---|
| Research Institution | The University of Tokushima |
|---|
Principal Investigator |
ISHIKAWA Yasuko The Univ. of Tokushima Sch. of Dentistry ; Assistant Professor, 歯学部, 助教授 (40144985)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
AMANO Ichiro The Univ. of Tokushima Sch. of Dentistry ; Research Associate, 歯学部, 助手 (20212566)
ISHIDA Hajime The Univ. of Tokushima Sch. of Dentistry ; Professor, 歯学部, 教授 (70028364)
|
|---|
| Project Period (FY) |
1991 – 1993
|
| Keywords | Parotid glands / Cell membrane / beta-adrenoceptors / Heterotrimetric G proteins / Monomeric G proteins / Secretory granules / Cell differentiation / Developmental changes |
|---|
| Research Abstract |
The postnatal alteration of the function of rat parotid glands was studied in relation to that of BETA adrenoceptor-adenylate cyclase system. The tissues of 1-week-old rats responded to isoproterenol(IPR) and caused amylase secretion. The EC_<50> value of the tissues for IPR in amylase secretion was ten time higher than that of adult rats. The tissues also responded to forskolin(FOR) and markedly caused amylase secretion. However, the secretory response of the tissues to FOR decreased during development. Binding experiments of [^3H]dihydroalprenolol(DHA) show that the specific binding of the ligand was already detected in parotid tissues of 3-day-old rats and Bmax value increased steadily until 4 week after birth when it leveled off to that of the tissues of adult rats. The IC_<50> values of IPR for [^3H]DHA binding in the tissues of 1-and 8-week old rats were 890 (〕SY.+-.〔) 74.2 and 3.5 (〕SY.+-.〔) 0.8muM, respectively. But the value of propranolol did not show any changes during devel
… More
opment. The c-AMP content in the tissues of 1-week-old rats also increased by the treatment with IPR as observed in adult rat tissues. The increasing ratio in the tissues of adult rats by IPR was twice as that of 1-week-old rats. FOR also caused remarkable increases in c-AMP content, but the response markedly decreased during development and paralleled amylase secretion. Binding experiments of [^<35>S]GTPgammaS showed the presence of GTP binding capacity of G proteins in the tissues of 1-week-old rats. The Bmax value of specific [^<35>S]GTPgammaS binding in the tissues in creased steadily during development, reaching plateau at 4 weeks after birth. The GTP binding capacities of Gs proteins and Gi proteins showed the same developmental increases.
These results show that the function of beta-adrenoceptor-adenylate cyclase system in rat parotid tissues is markedly enhanced during development and the superior efficacy of the beta-adrenergic stimuli for the induction of amylase secretion is to be found in adult rats. Less
|
