Arthur Arnold, PhD

Distinguished Professor, Physiological Sciences,David Geffen Department of Medicine at UCLA

Dr. Arnold studies factors that cause sex differences in normal physiology and disease. Although most sex differences are caused by gonadal hormones, he has studied the poorly understood and understudied sex differences caused by direct action of X and Y genes. He has developed a novel mouse model in which gonadal sex is no longer controlled by the Y chromosome, but has been transferred to an autosome. This model, called the "four core genotypes" (FCG), comprises four groups: XX and XY gonadal males, and XX and XY gonadal females. The comparison of these four groups allows to determine which sex differences are caused by gonadal secretions vs. sex chromosome complement (XX vs. XY), and it alsoallows to determine the interaction of these factors. In collaboration with Dr. Yvette Taché, Dr. Arnold found that when stressed (mild restraint stress), gonadectomized XY mice (relative to gonadectomized XX mice) exhibit a marked increase in colonic motility. Consequently, some sex differences in stress-induced colonic motility stem from differences in the expression of genes encoded on the X and Y chromosomes in males vs.females. Dr Arnold is interested in discovering the X or Y genes that control this sex difference, and determining the site of action of these genes within the circuits regulating the response. The objective of these novel studies is to achieve a better understanding of sex differences in the function of brain-gut systems.

arnold@ucla.edu
310-825-2169