biochemistry- Role of insulin in metabolism- PHYSIOLOGICAL ACTION OF INSULIN

INSULIN- ANTILIPOLYTIC, LIPOGENESIS, ANTI- KETOGENIC EFFECT, UTILIZATION OF GLUCOSE BY TISSUES, HYPOGLYCEMIC EFFECT
PHYSIOLOGICAL FUNCTION OF INSULIN
BIOCHEMISTRY

1. ROLEOFINSULININ
METABOLISM

2. ROLE OF INSULIN
1. Uptakeofglucosebytissues
2. Utilizationofglucose
3. Hypoglycemiceffect
4. Lipogenesis
5. Anti-lipolyticeffect
7. Anti-ketogeniceffect
7. Othergeneraleffects

4. Uptakeofglucosebytissues
Facilitatesthemembranetransport
ofglucose.
Facilitateddiffusionofmuscleis
enhancedbyinsulin.
InDM,thetransporter,GluT-4 is
reduced.
Glucoseuptakeinliveris
independentofinsulin.

5. Utilization of glucose
■Stimulate glycolysis
■Key glycolytic enzymes stimulated
■Glycogen synthase is activated.
■Overall effect hypoglycemia
Glucokinase
Phosphofructokinase
Pyruvate kinase

6. HYPOGLYCEMIC EFFECT
Gluconeogenesis is inhibited
Repress key enzymes
•Pyruvate carboxylase
•Phosphoenolpyruvate carboxylase
•Fructose-1,6-biphoshatase
•Glucose-6-phosphatase
Glycogenolysis is inhibited
•Inactivation of glycogen phosphorylase
•Inhibition of G-6-phosphatase
Blood glucose
level is lowered

7. LIPOGENESIS
Favored
Providing more acetyl CoA (from PDH reaction)
Increase activity of acetyl CoA carboxylase
Provides NADPH by increasing the GPD activity of the HMP shunt pathway.

8. ANTI-
LIPOLYTIC
EFFECT
■Inhibits lipolysis in
adipose tissue; inhibition
of HORMONE SENSITIVE
LIPASE
■Increased level of free FA
in plasma in diabetes

9. ANTI-KETOGENIC EFFECT
Depress HMG-CoA synthase
(inhibit ketogenesis)
Acetyl CoA –completely utilized in
TCA cycle because oxaloacetate is
plenty
Favor fatty acid synthesis from
acetyl CoA

10. Other
general
effects
Promote protein synthesis & degradation is retarded
An anabolic hormone -Inhibition of transaminases and ornithine transcarbamoylase
Stimulates replication of cells; essential growth factor in all mammalian cells.

11. Metabolic effects of insulin –Summary
Carbohydrate
metabolism
Lipid
metabolism
Protein
metabolism
•Glucose uptake by
tissues.
•Increase
Glycolysis(utilization).
•Decrease
Gluconeogenesis
•Favors synthesis of TAG.
•Decrease
lipolysis(hormone
sensitive lipase)
•Reduce ketogenesis(HMG
CoA synthetase).
•Increase utilization of
acetyl CoA in Krebs cycle.
•Enhance protein
synthesis
•Anabolic hormone

12. Summary of action of insulin

13. Insulinresistancestate–Appliedaspect
Normalvsinsulinresistancestate

14. THANK YOU