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Changes in phosphodiesterase activity in the developing rat submandibular gland.
Satoshi Tanaka1, Shohachi Shimooka, Hiromi Shimomura
1Department of Pediatric Dentistry, School of Dentistry at Niigata, The Nippon Dental University, 1-8 Hamaura-cho, Niigata 951-8580, Japan.
Archives of Oral Biology
|September 11, 2002
Summary
Phosphodiesterase (PDE) activity in rat submandibular glands changes during development. PDE4 is the primary enzyme for cAMP hydrolysis, while PDE1 and PDE2 play roles in cGMP regulation and potential growth pathways.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Pharmacology
Background:
- Phosphodiesterases (PDEs) regulate intracellular cyclic nucleotide signaling.
- The submandibular gland's development involves complex signaling pathways.
- Understanding PDE activity is crucial for comprehending gland function.
Purpose of the Study:
- To investigate developmental changes in phosphodiesterase (PDE) activity in rat submandibular glands from 2 to 26 weeks.
- To characterize the specific PDE isoforms present and their roles in cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) hydrolysis.
- To explore the influence of stimulators and inhibitors on PDE activity during gland development.
Main Methods:
- Submandibular gland homogenates were fractionated to isolate supernatant and pellet components.
- PDE activity assays were performed using various stimulators (Ca(2+)/calmodulin, cGMP) and inhibitors (cGMP, cilostamide, rolipram, zaprinast).
- Ion-exchange chromatography (Mono Q HR5/5), reverse transcriptase-polymerase chain reaction, and Western blotting were employed to identify PDE isoforms and their expression.
Main Results:
- PDE activity was predominantly found in supernatant fractions (70-90%) during development.
- PDE4 (cAMP-specific) was a major PDE isoform, indicating its primary role in cAMP hydrolysis.
- PDE1 showed increased cGMP hydrolysis in young rats, and PDE2 presence suggested a role for cGMP in submandibular gland growth.
- Chromatography and inhibition studies confirmed the presence of PDE1, PDE2, PDE3, PDE4, and PDE5 in young glands, and PDE1, PDE3, PDE4, and PDE5 in adult glands.
- PDE5 expression was confirmed through multiple methods.
Conclusions:
- Rat submandibular gland PDE activity undergoes significant developmental changes.
- PDE4 is the principal enzyme responsible for cAMP breakdown throughout development.
- The presence and activity of PDE1 and PDE2 suggest a regulatory role for cGMP in gland development and growth.
- Multiple PDE isoforms are expressed in the submandibular gland, with developmental variations in their presence and activity.