Thermoregulatory ontogeny in piglets: sympathetic and adipokinetic responses to cold
Curtis, S.E.; Rogler, J.C.
American Journal of Physiology 218(1): 149-152
1970
ISSN/ISBN: 0002-9513 PMID: 5410068 Document Number: 22466
The role of sympathetic function in postnatal amelioration of thermostability in piglets was studied. Sympathetic impairment (5 mg reserpine/kg body wt i/p) was more deleterious to resistance to cold at 30 than at 6 hours of age. It was concluded that sympathetically induced thermogenic response to cold improved during the first 2 days after birth. Plasma free fatty acid (FFA) levels 4 min. after noradrenaline injection (36 micro g/kg body wt i/v) were not raised in piglets aged 6 or 30 hours, but were at 54 and 78 hours. Similarly, after 15 min. exposure to 2 degrees C, plasma FFA were elevated in 60-hour-old, but not in 12-hour-old piglets. Thus, the adipokinetic response to noradrenaline or cold seemed to improve during the first two days after birth. This is the same period during which metabolic rate increases, ability to augment thermogenesis in response to cold improves, and thermostability is ameliorated. It is suggested that ontogeny of thermoregulatory capability in piglets involves (undoubtedly in conjunction with other factors) the assumption in older piglets of a larger portion of total heat production by lipid catabolism, which could conceivably result in higher warming efficiency of the heat produced and bette, utilization of carbohydrate.