May 20, 2013

Leptin, the Hunger Hormone

Many hormones and interactions are crucial to the dynamic process we call reproduction. What remains elusive is whether there is a single molecular switch, a common regulatory element that governs the process.

And along came leptin, a neurohormone which remains a candidate for this position.

Leptin, the hunger hormone,  is a hormone signal that wears many hats. It is involved in energy balance, neuroendocrine function (brain-signaling) and is involved in pubertal development. When energy imbalance is involved with reproductive dysfunction, leptin is partial culprit.

Both mouse and human-alike who are leptin-deficient display similar characteristics. They are obese, diabetic and infertile. There are many receptors(the tumblers) for leptin(the key) hormones throughout the body. Many of these organs and tissues, unsurprisingly, are involved in reproductive function (both the brain and the gonads). It is these receptors within the brain (the pituitary gland, actually) that are the major players in directing reproductive processes.

Leptin is made within adipose tissue and is responsive to the energy state of the body at any given time. For instance, in times of starvation, leptin levels fall quickly. Decreasing leptin levels signal energy-insufficiency and, in turn, promote regulatory responses that act to preserve or to generate more energy. With decreasing levels, appetite increases, activity decreases (unless in search of food). Those, non-essential activities are diminished as an adaptive process to this negative-energy state. One of those adaptations is quelling of the reproductive axis. In animal models, these starvation and nutrient-rich states can be manipulated easily. Predictably, rodents food-deprived rodents do not produce hormones to stimulate adequately an ovarian response (no mature eggs), have reduced LH-surges (no ovulatory signal) and cannot sustain an adequate pregnancy environment. When these same animals are replenished, their menstrual cyclicity returns (eggs are produced and ovulated) and fertility returns.

Stay tuned for more details on Leptin in upcoming blogs! If you have any questions or want to schedule a FREE initial consult, contact us!

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Danielle Vitiello, Ph.D., M.D.

Danielle Vitiello, Ph.D., M.D. Board-Certified in Obstetrics and Gynecology, Reproductive Endocrinology and Infertility