Levodopa with carbidopa diminishes glycogen concentration, glycogen synthase activity, and insulin-stimulated glucose transport in rat skeletal muscle -- Smith et al. 97 (6): 2339 -- Journal of Applied Physiology
Levodopa with carbidopa diminishes glycogen concentration, glycogen synthase activity, and insulin-stimulated glucose transport in rat skeletal muscle -- Smith et al. 97 (6): 2339 -- Journal of Applied Physiology
The data demonstrate -adrenergic-dependent inhibition of insulin action by levodopa-carbidopa and suggest that unrecognized insulin resistance may exist in chronically treated patients with Parkinson's disease.
Parkinson's disease; insulin resistance; diabetes; dopamine
PARKINSON'S DISEASE (PD) is a chronic progressive neurological disorder that affects up to one million North Americans with 50,000 more individuals diagnosed each year (4). Because the disease causes degeneration of dopamine-producing substantia nigra neurons, levodopa, a dopamine precursor that is able to cross the blood-brain barrier to enter the central nervous system, is used to replenish depleted dopamine (2, 4, 6). Levodopa is the most commonly prescribed and most effective medication for controlling the symptoms of PD (4).
Several investigators have reported high rates of glucose intolerance among patients with PD (2, 3, 27). For example, in two separate studies of 30 and 57 patients with PD, respectively, 50% of the patients displayed abnormal oral glucose tolerance (2, 27). Similarly, abnormal intravenous glucose tolerance was found in four of eight patients with PD (3). Notably, hyperglycemic effects of levodopa and dopamine have been documented in humans and laboratory animals (3, 17, 18, 33). The decarboxylase inhibitor carbidopa is given with levodopa to prevent the conversion of levodopa to dopamine in peripheral tissues, because dopamine does not cross the blood-brain barrier (4). However, carbidopa does not prevent accumulation of dopamine in skeletal muscle in animals treated with levodopa (9, 30)
Not sure what this means. Levodopa increases or decreases insulin?
The data demonstrate -adrenergic-dependent inhibition of insulin action by levodopa-carbidopa and suggest that unrecognized insulin resistance may exist in chronically treated patients with Parkinson's disease.
Parkinson's disease; insulin resistance; diabetes; dopamine
PARKINSON'S DISEASE (PD) is a chronic progressive neurological disorder that affects up to one million North Americans with 50,000 more individuals diagnosed each year (4). Because the disease causes degeneration of dopamine-producing substantia nigra neurons, levodopa, a dopamine precursor that is able to cross the blood-brain barrier to enter the central nervous system, is used to replenish depleted dopamine (2, 4, 6). Levodopa is the most commonly prescribed and most effective medication for controlling the symptoms of PD (4).
Several investigators have reported high rates of glucose intolerance among patients with PD (2, 3, 27). For example, in two separate studies of 30 and 57 patients with PD, respectively, 50% of the patients displayed abnormal oral glucose tolerance (2, 27). Similarly, abnormal intravenous glucose tolerance was found in four of eight patients with PD (3). Notably, hyperglycemic effects of levodopa and dopamine have been documented in humans and laboratory animals (3, 17, 18, 33). The decarboxylase inhibitor carbidopa is given with levodopa to prevent the conversion of levodopa to dopamine in peripheral tissues, because dopamine does not cross the blood-brain barrier (4). However, carbidopa does not prevent accumulation of dopamine in skeletal muscle in animals treated with levodopa (9, 30)
Not sure what this means. Levodopa increases or decreases insulin?
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