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Differential peroxidase activity in the thyroid gland and oviduct of a wild avian species, the tree pie (Dendrocitta vagabunda)

100%

Chaundhuri S. , Maiti B. R.

tom 45

41-46

The aim of the present investigation was to study peroxidase activity in different subcellular fractions of thyroid and oviduct and to ascertain whether there is any difference between the two sexes of peroxidase activity of the thyroid gland or between the thyroid and oviduct of a wild avian species, the tree pie (Dendrocitta vagabunda). Peroxidase activity was maximum in the soluble supernatant fraction of both the tissues with acetate buffer at pH 5.5, but the enzyme activity was highest even in low concentration of the substrate (H2O2) in the thyroid gland. Thiourea, thiouracil and azide inhibited enzyme activity in both thyroid and oviduct. While ascorbic acid inhibited peroxidase activity in the thyroid gland, it stimulated in the oviduct. Moreover, the enzyme activity was maximally inhibited by ascorbic acid in the thyroid and by thiourea in the oviduct. Peroxidase activity was highest with NAD+ in the thyroid and cytochrome C in the oviduct. Peroxidase activity was higher in females. It is suggested that avian thyroid/oviduct peroxidase activity may differ somewhat from that of mammals and possibly also in the peroxidase activity between the thyroid and oviduct of the tree pie.

Adrenomedullary and glycemic responses to ACTH, corticosterone, aldosterone, epinephrine and norepinephrine administrations in the soft-shelled turtle

80%

Ray P. P. , Chaudhuri-Sengupta S. , Maiti B. R.

tom 52

nr 1-2

73-80

The aim of the current investigation was to ascertain the role of ACTH and adrenal hormones on adrenomedullary and glycemic functions in soft-shelled turtles, Lissemys punctata punctata. All the experiments were carried out on sexually immature animals. Findings revealed that: (1) ACTH administration (0.5 IU/1.0 IU/2.0 IU per 100 g body wt. daily for 10 days) in all doses stimulated adrenomedullary function by increasing medullary cell nuclear diameter with elevations of norepinephrine, epinephrine and blood sugar levels. Only moderate and higher doses (50 mug/100 mug per 100 g body wt. daily for 10 days) of dexamethasone suppressed adrenomedullary activity and blood sugar level by reversing the changes to those of ACTH; the responses were dose-dependent. But these changes were no longer observed after ACTH treatment in dexamethasone (DMS) recipients (DMS: 100mug / 100 g body wt daily for the first 10 days and ACTH: 0.5 IU / 100 g body wt daily for the next 10 days); (2) Only moderate and higher doses (50 mug/100 mug per 100 g body wt daily for 10 days) of corticosterone increased adrenomedullary activity and blood sugar level and the responses were also dose-dependent. But aldosterone treatment in all doses (same as for corticosterone) had no significant effect on the adrenal medulla or blood sugar level; (3) Only moderate and higher doses of norepinephrine or epinephrine (same as for corticosterone) caused adrenomedullary atrophy with depletions of norepinephrine and epinephrine levels but elevated the glycemic level. The findings are briefly discussed.