Timothy G. Ramsay

In Vitro Systems for the Analysis of the Development of Adipose Tissue in Domestic Animals

In vitro models have been used for many years to assess processes that regulate metabolic activity of adipocytes or that regulate proliferation and differentiation of precursor cells for adipocytes (preadipocytes). The results of these studies have been useful in characterizing the role of various hormones and growth factors in regulating the cellular activities of preadipocytes and adipocytes from domestic animals. Mechanisms that regulate the proliferation and differentiation of the preadipocyte are currently being evaluated with the use of a variety of cell culture systems: matrix suspension, coverslip, micromass, clonal etc. Isolated cell culture of adipose tissue and the tools of molecular biology have allowed direct examination of the effects of potential regulatory hormones of adipogenesis upon gene expression during the development of adipose tissue in domestic animals. Much information has been collected by combining the use of in vivo animal manipulations and in vitro assay techniques to elucidate the mechanisms that affect adipocyte function or formation. The development of in vitro tools to manipulate the development of adipose tissue should result in an increase in our knowledge of the regulation of adipose tissue formation and thus should permit the development of methods to produce leaner and more efficient domestic animals.

Developmental changes in hepatic IGF-2 and IGFBP-2 mRNA levels in intrauterine growth-retarded and control swine☆

1. Significantly elevated levels of hepatic IGFBP-2 mRNA were detected in IUGR piglets at 90 days fetally and at birth (P < 0.05). 2. Developmentally, hepatic IGF-2 (P < 0.05) and IGFBP-2 (P < 0.01) mRNA levels were higher fetally and at birth than at 21 and 49 days of age. 3. This study provides new information concerning hepatic expression of IGF-2 and IGFBP-2 in developing swine.

Developmental changes in serum IGF-1 and IGFBP levels and liver IGFBP-3 mRNA expression in intrauterine growth-retarded and control swine

The 29 M(r) x 10(-3) IGFBP was significantly elevated (P < 0.01) in IUGR piglets at 90 days fetally and at birth. Developmentally, 29 M(r) x 10(-3) IGFBP levels were higher fetally and at birth than at 21 and 49 days of age (P < 0.05). At 90 days fetally, hepatic IGFBP-3 mRNA levels were very high, while circulating levels of IGFBP-3 were extremely low whereas postnatally, hepatic IGFBP-3 mRNA and serum IGFBP-3 levels were parallel. This study provides new information concerning the developmental expression of IGFBP-3 and the relationship between serum levels of the 29 M(r) x 10(-3) IGFBP and IUGR in swine.