Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

alpha-2 Adrenergic (A2) receptors and tyrosine hydroxylase (TH) mRNA in the locus coeruleus (LC) were studied using [125I]iodoclonidine and [35S]TH oligonucleotide probe. Spontaneously hypertensive (SHR) rats contained less TH mRNA at their prehypertensive, but not at the well-established hypertensive stage, than age-matched Wistar-Kyoto rats. Furthermore, there is an up-regulation of A2 receptors in SHR rats which is parallel to their blood pressure elevation. The present data suggest that increased A2 receptors in conjunction with TH mRNA reduction in the LC are associated with initiation, but not maintenance of genetic hypertension.
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PMID:Quantitative autoradiographic study on tyrosine hydroxylase mRNA with in situ hybridization and alpha 2 adrenergic receptor binding in the locus coeruleus of the spontaneously hypertensive rat. 168 39

Dopamine has been well recognized to be a precursor of norepinephrine, exhibiting cardiovascular effects through alpha-adrenoceptor stimulation by norepinephrine production and release in sympathetic nerve endings. It also has the specific and unique effects of natriuresis and vasodilation. Since dopamine is one of the important endogenous hypotensive and natriuretic substances, it is speculated that impaired dopamine generation and/or the disturbance of the effects of dopamine could cause hypertension with suppression of plasma renin activity and/or salt-sensitivity. A non-specific enzyme of aromatic L-amine acid decarboxylase (AAAD) converting from 3,4-dihydroxyphenylalanine (DOPA) to dopamine is widely distributed in the peripheral tissue, e.g. the sympatho-adrenomedullary system, the small intestine, the lung, the liver, the kidney, etc. Since tyrosine hydroxylase is a rate-limiting enzyme of catecholamine biosynthesis, DOPA generation in the neuronal tissues is accelerated with the sympathetic nerve activation by stress such as emotional and environmental changes, resulting in an increase of DOPA delivery to the non-neuronal tissues containing non-neuronal AAAD. More than five receptors for dopamine are cloned in the brain, and it is suggested that more than three different types of dopamine receptors are in the peripheral tissues. In spontaneously hypertensive rats, the post-receptor defect of renal dopamine D1-receptor has been proposed where peripheral dopamine generation compensatorily increased. In Dahl salt-sensitive rats, another model of genetic hypertension, the blunted response of urinary dopamine to sodium loading has been demonstrated. It is controversial whether abnormalities of the neuronal and/or non-neuronal (particularly renal) dopamine system play a contributory role on the pathogenesis of essential hypertension. However, it is plausible that the impairment of dopamine generation and/or the defective responses of a dopamine receptor might induce sodium retention and hypertension.
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PMID:[Dopamine and hypertension]. 826 73