ARS | Publication request: NEUROENDOCRINE-IMMUNE INTERACTION IN THE NEONATE

Submitted to: Domestic Animal Endocrinology
Publication Type: Review Article
Publication Acceptance Date: March 13, 1998
Publication Date: N/A

Interpretive Summary: The relatively high rates of death and sickness in neonatal pigs due to bacterial infections could be a result of immaturities in the immune system. Animal and human neonates tend to be weakly responsive to infectious triggers. We discovered significant age-dependent differences in several critical aspects of the response to infection in the baby pig. In contrast to the normal development of a mild fever observed in older individuals, one-day-old piglets developed a pronounced hypothermia (loss of body temperature). In addition, the typical production of protective hormones involved in immune response was considerably reduced in the newborns. These immaturities could contribute to the long-standing problems of high mortality and morbidity in neonatal pig production. This information may well be instrumental in reducing the high mortality and morbidity experienced by swine.

Technical Abstract: This report combines first-time presentation of data with a literature review on how interactions between immune and endocrine systems influence the physiology of neonatal livestock. Very young (1-d-old) and weaning age (21-28 d) pigs were injected with E. coli lipopolysaccharide (LPS) in order to evaluate febrile, endocrine, and immune responses. Body temperatures were significantly affected by LPS (P = .001), with a mild fever produced in the weaning age pigs and a pronounced hypothermia occurring in the 1-d-old piglets. The concentrations of mRNAs for the cytokines(immune system hormones) TNF-alpha and IL-6 were elevated by LPS injection in neuroendocrine (pituitary, hypothalamus) and peripheral (liver, thymus, spleen) tissues (P < .0001). Levels of IL-6 were highest (P < .0001) and increased with age (P < .05) in the neuroendocrine tissues. TNF-alpha mRNA levels were highest in peripheral tissues (P < .0001), and increased with age in thymus (P < .05). Serum IL-6 responses were equivalent among age groups, but TNF-alpha responses were greatest in older pigs (P < .05). Serum cortisol and prolactin concentrations were increased by LPS (P < .0001), while serum GH was unaffected and circulating TSH and thyroid hormone decreased (P < .05). Serum cortisol responses were greatest in the older animals (P = .001). The results suggest functional interactions between endocrine, thermoregulatory, and immune systems in neonatal animals,which could have a significant influence on health and productivity.