Excretion of Catecholamines in Rats Exposed to Cold

Abstract

The chemical regulation of heat production which is now well demonstrated in rats has been first postulated to be mediated through the release of adrenaline from the adrenal medulla (MORIN 1948). Recently emphasis has been put on the possible role of noradrenaline as the mediator of the non-shivering heat production (HSIEH and CARLSON 1957). It was then felt important to study the excretion of catecholamines in rats exposed to cold, as a measure of their production.Rats of the Sprague-Dawley strain weighing 170-180 g were selected.They were kept in wire cages and exposed to a temperature of + 3" C for one month. At all times rats had access to food and water. Controls were maintained at room temperature. Catecholamines in 24 hours urine and in adrenal glands were estimated according to the method of EULER and LISHAJKO (1959). As seen in the figure rats increase their excretion of noradrenaline very rapidly on exposure to cold. The response is thus nearly maximal already in the first period of 24 hours. The noradrenaline output shows a slow decline with time, but is still four times as high as in the control group after one month in the cold. The adrenaline excretion increases gradually to a maximum in 6 to 8 days and decreases rapidly thereafter.In the adrenal glands, adrenaline was reduced 25 yo after 24 hours in the cold, followed by an increased content which persisted as long as rats were kept in the cold room. The noradrenaline content did not show any significant change.Adrenalectomized rats excreted as much noradrerialine as intact animals on exposure to cold. However, the adrenaline output in urine, although significantly increased in the cold, was lower than in the control group.

Chronic Cold in Adrenalectomized, Corticosterone (B)-Treated Rats: Facilitated Corticotropin Responses to Acute Restraint Emerge as B Increases1

“…Adrenalectomized rats do not survive in cold (40,41) and we made no attempt to test this. Nonetheless, of 49 adrenalectomized rats prepared with B pellets, 7 rats that were targeted for the low range of B did not survive the 5-day cold exposure period; death occurred between 2 and 3 days.…”

Contrd of Thyrotrophic Hormone (TSH) Secretion by the“Heat Loss Center”

“…Many experimental studies have later confirmed that cold exposure causes increased thyroid and adrenal medullary activation. Apparently not only adrenaline but also noradrenaline is secreted in increased amounts under such circumstances (LEDUC 1961). The thyroid and the sympathetic nervous system, including the adrenal medulla, thus appear to be important in the metabolic response to cold.…”

Factors involved in maintenance of cardiac catecholamine content: relative importance of synthesis and re‐uptake

“…Exposure to cold is known to result in an increased release of catecholamines from tissue stores (Leduc, 1961), presumably due to increased sympathetic nervous activity, since pretreatment with ganglionic blocking agents prevented release of noradrenaline (Leduc, 1961). Several studies indicate that the noradrenaline released from the heart during cold exposure was derived from all three subcellular fractions: coarse, particulate and soluble (Gutman & Weil-Malherbe, 1967).…”