| Summary: | The purpose of this investigation was to determine whether or not the adrenocortical steroids influence the activity of the avian supra-orbital gland. In the intact saline loaded duck (Anas platyrhynchus), a diphasic excretory pattern was apparent, as an urinary diuresis was followed by activation of the supra-orbital glands. Variations in the circulating levels of adrenocortical steroids resulted in qualitative and quantitative changes in both phases of this response.
Injection of exogenous, cortisol, cortexone and aldosterone caused an initial increase in the rate of nasal discharge and a consequent increase in the total output of Na⁺ and K⁺. Conditions of selective adrenocortical activity, i.e., subtotal adrenalectomy, severely impaired the extra-renal response while total adrenalectomy completely obliterated the response to an osmotic stimulus. The activity of the supra-orbital gland in the totally adrenalectomized duck was restored after treatment with cortisol.
The renal phase in ducks treated with adrenocortical steroids was modified when compared to the control response. Administration of cortisol prior to saline loading resulted in a significantly lower total output of sodium although the volume of urine excreted did not differ from the control value. Treatment with aldosterone resulted in a significantly lower renal output of both Na⁺ and K⁺ as well as a decrease in urine volume. Cortexone and ACTH showed the control renal pattern of excretion.
Unilateral adrenalectomy caused no apparent change in the renal excretory pattern whilst total adrenalectomy caused a significant increase in the total volume of urine excreted as well as on increase in the total output of Na⁺ and K⁺. Totally adrenalectomized birds maintained on cortisol reverted to a normal excretory pattern.
The influence of adrenocortical steroids on the control of the avian supra-orbital gland is discussed. It can be said with certainty that adrenocortical steroids influence the activity of the supra-orbital gland of the Domestic Duck (Anas platyrhynchus). Furthermore, cortisol administered to the adrenalectomized animal reactivates the gland suggesting that a glucocorticoid is essential for its function. === Science, Faculty of === Zoology, Department of === Graduate
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