A new study has found that insulin administered intranasally, severely decreases food intake in men but not women and moreover, the compound boosts memory function in women but not men.
Researchers at the University of Lubeck in Germany said their findings signify that gender is a decisive factor in brain insulin signalling that affects both food intake and cognitive functions.
"They further suggest that intranasal insulin may be helpful in the treatment of cognitive and metabolic disorders like Alzheimer's disease and obesity that are assumed to derive at least in part from malfunctions of central nervous insulin signalling," said lead author Dr. Christian Benedict.
Previous studies have shown that insulin plays a key role in the regulation of central nervous functions such as energy metabolism and memory processing.
According to Dr. Benedict, they conducted the study to assess the effects of a single dose of intranasal insulin on these functions and to find out any gender differences.
For the study, 14 men and 18 women were administered regular human insulin intranasally before performing a battery of cognitive tests. Subsequently, study subjects took part in a breakfast buffet and their food intake was measured.
The nasal spray device used in this study atomizes the insulin solution before inhalation so that it penetrates the nasal cavities more effectively.
The pancreatic hormone insulin plays a pivotal role in the regulation of central nervous functions such as the neuroendocrine control of energy metabolism and memory processing.
Insulin reaches the brain via a saturable transport system, and binds to receptors primarily located in cerebral cortex, olfactory bulb, hippocampus, cerebellum, and hypothalamus.
The findings showed that men are more sensitive to the central anorexigenic actions of insulin whereas women benefit to a greater extent from its acute cognitive effects.
"Gender differences will have to be considered in the possible future development of intranasal insulin therapeutics," said Dr. Benedict.
The study is published in the Journal of Clinical Endocrinology & Metabolism (JCEM).