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. Author manuscript; available in PMC: 2018 Aug 16.
Published in final edited form as: Neuron. 2017 Aug 16;95(4):757–778. doi: 10.1016/j.neuron.2017.06.014

Figure 6. The adipocyte hormone, leptin.

Figure 6

Low levels of leptin signal to the brain that fat stores are inadequate (Ahima et al., 1996; Rosenbaum and Leibel, 2014).

(A) A control sibling (left) sitting next to a homozygous leptin-deficient, very obese mouse (right). Image courtesy of R.L. Leibel (2008) Int. J. Obes. 32, S98, 2008.

(B) Decreased food intake reduces fat stores and lowers blood leptin levels. This is sensed by the brain, which then brings about adaptive changes in appetite and energy expenditure – both aimed at restoring fat stores.

(C) A schematized dose response curve for blood leptin levels and their effects on satiety and energy expenditure. The effective range for leptin is between the low levels seen with fasting and the normal levels seen in the ad libitum fed, non-obese state. Levels above this, as occur with obesity or with exogenous leptin treatment, produce little additional effects – i.e. the dose response curve at higher levels of leptin is relatively flat.