The acute effects of injection of thyrotrophic hormone or of electrical stimulation of the hypothalamus on thyroid activity

Abstract

Harris & Woods (1958) The ideal method of measuring the activity of endocrine glands appears to be to measure the rate of secretion of hormone into the blood stream; that is, to measure the hormone content of the arterial blood to, and the venous blood from, the gland and the rate of blood flow through it. Various attempts which approximate to the ideal method, in that measurements were made of the hormone content of the glandular venous blood, have been reported (adrenal medulla, Satake, Sugawara & Watanabe, 1927; Brucke, Kaindl & Mayer, 1952; Duner, 1953; Folkow & von Euler, 1954;Satake, 1955; adrenal cortex, Vogt, 1943 adrenal cortex, Vogt, , 1944Bush, 1951;Nelson & Hume, 1955;Reif & Longwell, 1958; neurohypophysis, Andersson, 1951; Ginsburgh & Heller, 1953;Fitzpatrick & Hughes, 1957; testis, Samuels, 1957). Soderberg (1958) cannulated thyroid veins in anaesthetized cats and rabbits and presented clear results on the rate of thyroid blood flow, rate of iodine uptake and rate of secretion of labelled thyroid hormone. The techniques developed by Soderberg were applicable to observations extending over periods of seconds to minutes and were used to determine the effects on thyroid blood flow and activity of interference with the nerve supply to the gland or the administration of various substances.

Radioactive Iodine in the Lymph Leaving the Thyroid Gland

“…Again the radiation dose to the thyroid in our experiments was not greater than is customarily given in studies of hormone release from the thyroid [e.g. Campbell, George and Harris, 1960] and the dosage used by these workers and ourselves gives a lower level of radiation than that which is thought to cause radiation damage to the gland. Since, therefore, we can discount damage to the thyroid as a cause for the release of iodinated protein, it seems likely that a significant proportion of organic iodine leaves the gland under normal conditions via the lymphatic pathway both before and after the administration of TSH and that this pathway should be taken into account in all studies of thyroid secretion.…”

Human thyroid blood flow response to endogenous, exogenous human, and bovine thyrotrophin measured by electromagnetic flowmetry

“…Other investigators found no change in TBF after administration of TSH to rabbits (Campbell et al 1960;Taurog et al 1964), cats (Taurog et al 1964), dogs (Rosenberg et al 1960(Rosenberg et al , 1961Dumont & Rocmans 1964;Stark et al 1965;Isaacs et al 1966;Dumont 1971;Roc¬ mans et al 1978), or rats (Goldman 1963). Gold¬ smith et al (1965) found no change in TBF in a dog after injection of 10000 mlU TSH but noted a temporary decrease after 5000 mlU.…”

Vasopressin and thyroid function in the rabbit

“…Previous work (Soderberg, 1958;Campbell, George & Harris, 1960) demonstrated an increased radioactivity in the venous blood from thyroid glands 15-20 min after intravenous injection of TSH. The hormone in these glands had been previously labelled with 131I.…”

“…Vasopressin infusions The initial finding that injection of Pitressin results in an increased discharge of radioactivity from the thyroid gland came from observations on anaesthetized rabbits, in which measurements of the radioactivity in thyroid vein and arterial blood were being made by the technique described by Campbell et al (1960). In these preliminary experiments the responses varied from animal to animal and might have been due to TSH contamination of the posterior lobe extract used.…”