ABSTRACT
Dopamine-ß-hydroxylase (DBH) is a neurotransmitter (catecholamine)-mediating enzyme, which catalyzes the formation of norepinephrine from dopamine. The levels of DBH activity, its coenzyme (ascorbic acid) and cofactor (Cu(++)) and other biochemical parameters were measured in the serum of 32 arsenicosis patients of Bangladesh at three different age groups, namely, group 1 (10-18 years, 9 patients), group 2 (19-40 years, 14 patients) and group 3 (41-70 years, 9 patients) of the locality of Stadium Para of Meherpur district of Bangladesh. The values were compared with the same number of age-matched normal healthy individuals of the respective group. DBH activity was markedly decreased in the patients of group 1 as compared to that of the normal healthy people. The activities of DBH were decreased to lesser extents for the other two age groups. The total protein contents in the serum of arsenicosis patients were also significantly low as compared to that in the age-matched control groups. The levels of ascorbic acid and copper were found to be decreased in the serum of arsenicosis patients. The serum glucose levels were elevated in arsenicosis patients, as compared to that of the respective healthy controls. Other parameters, such as zinc and vitamin A levels were also decreased in the serum of arsenicosis patients. It was evident from the results of drinking of the arsenic contaminated water of shallow tube wells that the levels of DBH activity decreased significantly as compared to the control healthy persons. The levels of proteins, ascorbic acid, copper, zinc and vitamin A were decreased in the serum of people drinking the arsenic contaminated tube wells water as compared to that in the control healthy people with the exception that the levels of glucose were elevated in the serum of these patients. The pathophysiological significance of the results could be correlated with the decreased in proteins and that in DBH activities as DBH deficiency is characterized by lack of sympathetic noradrenergic function.The general physiologic findings of autonomic function indicate that complete DBH deficiency include minimal or absent plasma norepinephrine and epinephrine.
ABSTRACT
Dopoamine-ß-hydroxylase (DBH) is a catecholamine-synthesizing enzyme which catalyzes the formation of norepinephrine from dopamine. Fifty nine Long-Evans rats of 1 week-old were used to grow on normal diets in 7 different developmental stages, viz., 15 rats in 1 week-old group, 9 rats in 2 weeks-old group, and the remaining 35 rats were divided equally into five groups, 7 rats in each group of 5-, 8-, 12-, 15- and 27-weeks old for systematic developmental studies of DBH. At the end of each developmental period, weights of rats were recorded for that specific group and they were sacrificed. The brain tissues (caudate nucleus, hypothalamus, brain stem, colliculi, cerebral cortex and cerebellum) and peripheral tissues (liver, heart, kidney, adrenal, spleen, pancreas, lung and small intestine) and serum were collected. The brain tissues had the highest activity (expressed as nmole/min/g of wet weight tissue) of DBH at 5 weeks of age. The hypothalamus had the highest activities (11.5 ± 2.2) and the lowest activities were found in the cerebellum (5.7 ± 0.9). The peripheral tissues also showed the peak DBH activities at 5 weeks of age and adrenals had the highest activities (59.2 ± 7.0) among the central and peripheral tissues. The serum DBH activities were relatively low (1.3 ± 0.2) as compared to those in all other tissues. The highest serum DBH activities (1.28 ± 21 nmole/min/ml of serum) were also found in the 5- weeks-old rats. The specific activities of DBH were also measured in various developmental stages and the results were found to be in agreement with the DBH activities expressed in terms of gram of tissues or milliliter of serum. The Km and Vmax values for DBH were measured in the serum samples of each group and the highest Vmax values (78.3 ± 21.2 pmol/min/mg protein) were obtained at 5 weeks of age; while the lowest Km values (0.52 ± 0.04 mM) were obtained at this stage of age.
