The following paragraph is the abstract of the review paper" Leptin Effects on
Pancreatic B-Cell Gene Expression and Function
"The hormone leptin is secreted from white adipocytes, and serum levels of
leptin correlate with adipose tissue mass. Leptin was first described to act on
the satiety center in the hypothalamus through specific receptors (leptin
receptor [ObR]) to restrict food intake and enhance energy expenditure.
Important peripheral actions of leptin involve inhibition of insulin biosynthesis
and secretion in pancreatic ẞ-cells. In turn, insulin stimulates leptin secretion
from adipose tissue, establishing a hormonal regulatory feedback loop-the so-
called "adipo-insular axis." Multiple signal transduction pathways are involved in
leptin signaling in pancreatic ẞ-cells. We have identified the proinsulin gene and
protein phosphatase 1 gene as leptin repressed genes and the gene for the
suppressor of cytokine signaling 3 protein as a leptin-induced gene in pancreatic
B-cells. The molecular effects of leptin culminate to restrict insulin secretion and
biosynthesis to adapt glucose homeostasis to the amount of body fat. In most
overweight individuals, however, physiological regulation of body weight by
leptin seems to be disturbed, representing "leptin resistance." This leptin
resistance at the level of the pancreatic ẞ-cell may contribute to dysregulation of
the adipo-insular axis and promote the development of hyperinsulinemia and
manifest type 2 diabetes in overweight patients."
The paper explains how leptin can modulate insulin levels in mice and humans.
Determine which of the following effects of leptin have to do with gene
expression and which do not.
Leptin only has an effect on
cells that contain the leptin
receptor (OBR)
ob/ob mice (with a recessive
mutation in the leptin gene Ob)
are obese
Presence of mRNA for leptin
receptor was present in murine
pancreatic islets but not in the
exocrine pancreas
Leptin reduces insulin levels
produced in the pancreas
Leptin reduces mRNA of pre-
Not able to determine if gen
Example of effect of leptin
Example of effect of leptin n
Example of effect of leptin
Example of effect of leptin n
