Abstract

The prenatal environment has been shown to have lasting effects on cardiovascular health. In the present study, pregnant rats were fed a 0.7% NaCl normal salt (NS) diet or an 8% NaCl high salt (HS) diet throughout pregnancy. Adult offspring were fitted with radiotelemetry probes to continuously measure blood pressure and heart rate. Rats were placed in restraining cages to test for a programmed acute stress hyperresponsiveness. Offspring were challenged with HS diet for one week to determine if blood pressure salt sensitivity had been programmed by the prenatal HS diet. Animals were killed following resting and acute stress conditions, after which brains and blood were collected for in situ hybridization for corticotropin releasing hormone (CRH) and radioimmunoassay for corticosterone. In order to determine the contribution of gene expression to differences seen, total brain RNA was analyzed with microarray. Rats were injected with a ganglionic blocker and an adrenergic receptor antagonist before restraint to examine the autonomic component of the stress response. High salt offspring of either sex did not have basal hypertension. Female HS offspring had an increased pressor and tachycardic response to acute stress compared with NS females. There were no differences between male NS and HS offspring during acute stress. Salt sensitivity was not induced during high salt challenge. According to the microarray, 11 genes were upregulated and 10 were downregulated in adult brains, while 17 were upregulated and 17 were downregulated in pup brains. These data indicate that there are long-term changes due to HS diet. CRH levels were higher in the paraventricular nucleus (PVN) of female HS offspring than in female NS offspring during both basal and stressed conditions, though no differences were seen in CRH expression levels of male offspring. Autonomic blockade completely abolished the enhanced tachycardic response seen in female HS offspring. However, a difference in NS and HS blood pressures remained. Thus, female offspring of mothers fed an 8% NaCl diet have alterations in cardiovascular control, indicated by an enhanced tachycardic response as adults, due to changes in the autonomic nervous system, and enhanced pressor response to stress mediated by unknown mechanisms.

Degree

MS

College and Department

Life Sciences; Physiology and Developmental Biology

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2007-08-03

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd2061

Keywords

fetal programming, rat, hypertension, acute stress, microarray

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