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)

Sensory neurons of adult rat lumbar dorsal root ganglia were labeled in cryostat sections with antisera against tyrosine hydroxylase (TH), substance P (SP), and somatostatin (SOM), and with a monoclonal antibody (RT97) that labels the 145- and 200-kilodalton (kd) subunits of neurofilaments. These neurons were also histochemically stained for fluoride-resistant acid phosphatase (FRAP), and the size and distribution of each population were determined. In addition, the double-label immunoperoxidase technique of Sternberger and Joseph (Sternberger, L.A., and S.A. Joseph (1979) J. Histochem. Cytochem. 27: 1424-1429) was employed to determine whether these antibodies labeled distinct or overlapping populations of neurons. The results indicate that the dopaminergic (TH+) cells constitute a separate population from the SP+ and SOM+ neurons and that the size distributions of the SP+, SOM+, TH+, and FRAP+ cells are all different despite the fact that all of these subpopulations are part of the "small dark" subpopulation as indicated by their size and by the fact that they are RT97-. RT97 is a putative marker for the "large light" population (Anderton, B., H.B. Coakham, J. A. Garson, A.A. Harper, and S.N. Lawson (1982) J. Physiol. (Lond.) 334: 97-98P). Furthermore, the distribution data indicate that all of the "small dark" cell subpopulations are not evenly distributed within the ganglion, and the staining with RT97 and with another antibody which recognizes the 68-kd neurofilament subunit indicates heterogeneity among the "large light" population. These results are discussed in terms of the significance of the "small dark"-"large light" classification.
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PMID:An immunohistochemical and quantitative examination of dorsal root ganglion neuronal subpopulations. 241 May 79

Explants of rat adrenal medulla were cultured in defined medium for up to 22 hr. Addition of dopamine to the medium led to a diminution in the activity of tyrosine hydroxylase (tyrosine 3-monooxygenase; EC 1.14.16.2) in the tissue. The enzyme activity was inversely proportional to the concentration of dopamine in the culture medium. The extent of loss of tyrosine hydroxylase, as measured by immunochemical titration, corresponded to the degree of loss in enzyme activity under the same conditions. The decreased amount of enzyme protein was due to a decrease in the rate of synthesis of tyrosine hydroxylase. However, this effect was not specific in that the relative rate of tyrosine hydroxylase synthesis was not decreased. Metabolites of dopamine when added to the medium did not affect tyrosine hydroxylase activity. Two other adrenal medullary enzymes, monoamine oxidase (EC 1.4.3.4) and acid phosphatase (EC 3.1.3.2), were not affected by addition of dopamine to the medium. The results indicate that elevated cytoplasmic levels of dopamine decrease the concentration of tyrosine hydroxylase by inhibiting protein synthesis.
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PMID:Effect of dopamine on tyrosine hydroxylase in cultured rat adrenal medulla. 289 55

Vitiligo is a common dermatological disorder characterized by the development of complete pigment loss from focal lesions that tends to increase in size over time. The etiology of vitiligo, resulting in the disappearance of functional melanocytes from involved skin, is not clearly understood. As a consequence, no satisfactory therapy has been developed. A subtype of vitiligo, termed 'occupational' or 'contact' vitiligo, is increased in individuals who are exposed to materials containing phenolic derivatives, such as 4-tertiary butylphenol (4-TBP). Phenolic derivatives are structurally similar to tyrosine, the initial substrate of tyrosinase in the biochemical synthesis of melanin. Therefore, it has been proposed that phenolic derivatives compete with tyrosine for hydroxylation by tyrosinase and interfere with the completion of melanin synthesis and/or generate cytotoxic intermediates. Our results demonstrated that 4-TBP competitively inhibited both tyrosine hydroxylase and dihydroxyphenylalanine (DOPA) oxidase activities of tyrosinase, i.e., the first two catalytic steps in the biochemical conversion of tyrosine to melanin in cultured human melanocytes. This inhibition occurred at concentrations that did not influence the viability of melanocytes. The tyrosinase activity inhibited by 4-TBP was recovered after removing the treatment. 4-TBP did not affect the function of other enzymes, such as succinate-tetrazolium reductase, acid phosphatase and sulfatase. Since depigmentation occurred without a cytotoxic response after exposure of melanocytes to low concentration of 4-TBP, it is unclear whether the interaction between 4-TBP and tyrosinase leads to the destruction of the melanocytes in 'contact/occupational' vitiligo.
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PMID:Effects of 4-tertiary butylphenol on the tyrosinase activity in human melanocytes. 1045 91

Despite the important physiological role of periosteum in the pathogenesis and treatment of osteoporosis, little is known about the structural and cellular characteristics of periosteum in osteoporosis. To study the structural and cellular differences in both diaphyseal and metaphyseal periosteum of osteoporotic rats, samples from the right femur of osteoporotic and normal female Lewis rats were collected and tissue sections were stained with hematoxylin and eosin, antibodies or staining kit against tartrate resistant acid phosphatase (TRAP), alkaline phosphatase (ALP), vascular endothelial growth factor (VEGF), von Willebrand (vWF), tyrosine hydroxylase (TH) and calcitonin gene-related peptide (CGRP). The results showed that the osteoporotic rats had much thicker and more cellular cambial layer of metaphyseal periosteum compared with other periosteal areas and normal rats (P < 0.001). The number of TRAP(+) osteoclasts in bone resorption pits, VEGF(+) cells and the degree of vascularization were found to be greater in the cambial layer of metaphyseal periosteum of osteoporotic rats (P < 0.05), while no significant difference was detected in the number of ALP(+) cells between the two groups. Sympathetic nerve fibers identified by TH staining were predominantly located in the cambial layer of metaphyseal periosteum of osteoporotic rats. No obvious difference in the expression of CGRP between the two groups was found. In conclusion, periosteum may play an important role in the cortical bone resorption in osteoporotic rats and this pathological process may be regulated by the sympathetic nervous system.
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PMID:Structural and cellular features in metaphyseal and diaphyseal periosteum of osteoporotic rats. 2023 37