Effect of Acute Stress on the Pituitary Gland: Endocrine Gland Blood Flow

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Abstract
The minimal blood flows through the anterior and posterior pituitary, adrenal and thyroid glands and median eminence were determined in female Wistar rats using a rubidium86 method. Maximum change in blood flow occurred 2.5 min after the onset of a 1-min ether stress. At this time anterior pituitary flow had increased by about 40% and thyroid flow had doubled. Flows for the other glands were unchanged. Adenohypophysial blood flow in unstressed adrenalectomized rats was significantly elevated; stress again increased the flow by about 45%. In these animals, the posterior pituitary responded to stress with a 67% increase in flow. However, thyroid flow failed to increase. A blocking dose of hydrocortisone in intact rats did not alter the resting anterior pituitary blood flow, nor did it suppress the increased flow response to stress. The increased adenohypophysial flow after adrenalectomy appears to be autoregulated by glandular metabolism. However, the additional rapid increase after stress suggests that a vasomotor mechanism also controls adenohypophysial activity.