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EN
Adult female turtles (Lissemys punctata punctata) were treated with pineal indoleamine melatonin (100 mug/100 g) or the antithyroid agent, methylthiouracil (100 mug/100 g) or melatonin together with methylthiouracil (100 mug of each drug/100 g) for 12 days. Melatonin alone inhibited thyroid activity as evidenced by reductions in the gland weight, follicular epithelial cell height, thyroid peroxidase, and plasma thyroxine levels. Methylthiouracil caused hyperplasia of the gland, although it inhibited thyroid activity and reduced thyroid peroxidase and plasma thyroxine levels. Melatonin together with methylthiouracil produced changes similar to those obtained with melatonin alone. The results indicate that melatonin probably exerts inhibitory effects influences on both thyrotropin release from the pituitary and the activity of the thyroid itself in turtles.
Folia Biologica
|
2002
|
vol. 50
|
issue 3-4
115-120
EN
The aim of the current work was to investigate the role of gonadotropins and female sex hormones on interrenal activity in soft-shelled turtles, Lissemys punctata punctata. 1) FSH treatment (3 mug/100 g body wt daily for 10 days) caused interrenal hypertrophy with increased nuclear diameter, raises of acid phosphatase and alkaline phosphatase concentrations, and depletions of cholesterol (except the free fraction) and ascorbic acid levels from the interrenal gland. However, LH treatment (3 mug/100 g body wt daily for 10 days) failed to produce any perceptible change in the interrenal activity. The combined treatments of FSH and LH (3 mug each/100 gm body wt daily for 10 days) produced no further change beyond that of FSH alone. 2) Estrogen treatment with the low dose (25 mug/100 g body wt daily for 10 days) had no effect, but with higher doses (50 mug or 100 mug/100 gm body wt daily for 10 days) is caused interrenal stimulation by inducing the same manifestations to those of FSH. The degree of manifestations was higher with the higher dose (100 mug daily) than that of the moderate dose (50 mug daily). Progesterone treatment with the low dose (25 mug / 100 g body wt daily for 10 days) had no significant effect, but with the moderate (50 mug daily) and higher (100 mug daily) doses suppressed interrenal activity by showing the reverse changes to those of estrogen. The degree of manifestations was higher with the higher dose than that of the moderate one. The combined treatments of estrogen and progesterone (100 mug each/100 g body wt daily for 10 days) caused interrenal stimulation but to a lesser extent than that of estrogen alone. The findings are briefly discussed.
EN
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.
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