Mellor D J
Department of Physiology and Anatomy, Massey University, Palmerston North, New Zealand.
Equine Vet J Suppl. 1993 Apr(14):17-22. doi: 10.1111/j.2042-3306.1993.tb04803.x.
Physiological challenges facing the perinatal individual are huge. This is partly because of the marked and abrupt change from the intrauterine to the extrauterine environment, but also because the physiological responses to that change depend upon systems whose maturation is affected markedly by birth. Perinatal maturation appears, therefore, both to precede and accompany the physiological adaptations required for neonatal survival. This review does not provide a comprehensive coverage of perinatal physiology but directs attention towards evaluating constraints on foetal and neonatal thermogenesis, especially those imposed by post-natal availability of metabolic fuels in body reserves deposited before birth and acquired in colostrum and milk after birth. The relative importance of the supply of carbohydrate from body reserves and colostrum is examined. Carbohydrate is the major rate-limiting substrate with respect to heat production. It is shown that in the normal birth environments of several species, including the horse, colostral supply of lactose is not adequate to meet the entire carbohydrate needs of the neonate. It must, therefore, draw on its body glycogen reserves to sustain the required rates of heat production during the first day after birth. Gastrointestinal maturation and growth play a major part in the initial and continued provision of substrates for general metabolism and growth. Pre-natal and post-natal development of the stomach and intestines in a number of species are considered, including their disproportionately large growth compared with the body as a whole during the first 1-3 days after birth. Possible contributions to gastro intestinal growth and body growth of milk-borne growth factors such as epidermal growth factors and the insulin-like growth factors are considered. The role, as a possible significant stimulus to gastrointestinal growth and maturation immediately after birth, of the high levels of these growth factors in colostrum is evaluated.
围产期个体面临的生理挑战巨大。部分原因是从子宫内环境到子宫外环境的显著且突然的变化，还因为对这种变化的生理反应取决于其成熟度受出生显著影响的系统。因此，围产期成熟似乎既先于又伴随新生儿生存所需的生理适应。本综述并非全面涵盖围产期生理学，而是将注意力引向评估对胎儿和新生儿产热的限制因素，尤其是那些由出生前储存于体内的代谢燃料以及出生后从初乳和乳汁中获取的代谢燃料在产后的可利用性所施加的限制。研究了来自体内储备和初乳的碳水化合物供应的相对重要性。碳水化合物是产热的主要限速底物。结果表明，在包括马在内的几个物种的正常出生环境中，初乳中乳糖的供应不足以满足新生儿对碳水化合物的全部需求。因此，新生儿必须利用其体内糖原储备来维持出生后第一天所需的产热速率。胃肠道的成熟和生长在为一般代谢和生长持续提供底物方面起着主要作用。考虑了一些物种胃和肠道的产前和产后发育情况，包括它们在出生后1 - 3天内与整个身体相比不成比例的大幅生长。还考虑了诸如表皮生长因子和胰岛素样生长因子等乳源性生长因子对胃肠道生长和身体生长的可能贡献。评估了初乳中这些生长因子的高水平作为出生后立即对胃肠道生长和成熟的可能重要刺激因素的作用。
