Lean heart: Role of leptin in cardiac hypertrophy and metabolism

Table 1 Effects of leptin on cardiac mass and left ventricular hypertrophy

	Ref.	Findings	Effect of leptin on LVH
In vitro experiments	Rajapurohitam et al[23]	Exposure of cultured neonatal rat ventricular myocytes to leptin (0.31 to 31.4 nmol/L) increased cell area by 42%	Pro-hypertrophic
	Xu et al[25]	Exposure of cultured neonatal rat cardiomyocytes to leptin (1-1000 ng) for 4 h increased cell surface area	Pro-hypertrophic
	Piñieiro et al[27]	Exposure of murine HL-1 cells to leptin did not increase cell size of cardiomyocytes	Neutral
	Madani et al[24]	Treatment of human pediatric cardiomyocytes with 6 nmol/L leptin increased cell size by 60%	Pro-hypertrophic
	Tajmir et al[26]	Treatment of HL-1 cells with 60 nmol/L leptin increased cell numbers 2.3-fold	Pro-hypertrophic
In vivo experiments	Barouch et al[33]	6-mo-old leptin deficient ob/ob mice had increased myocyte diameters compared with wild-type mice. Leptin (iv) treatment in ob/ob mice completely reversed LVH and normalized wall thickness as well as reduced cellular hypertrophy by approximately 25%. Pair-feeding did not significantly reduce LV mass despite similar weight loss	Anti-hypertrophic
	Hall et al[35]	db/db mice developed LVH (increased wall thickness and heart weights). Transgenic db/db mice with cardiomyocyte-specific leptin receptor rescue did not cause LVH; in fact the heart weights were reduced	Anti-hypertrophic
Epidemiologic studies	Paolisso et al[28]	Plasma leptin level was correlated (n = 55 males) with interventricular wall (r = 0.34) and posterior wall (r = 0.38) thicknesses after adjusting for BMI and waist/hip ratio	Pro-hypertrophic
	Paolisso et al[18]	Study of 36 hypertensive patients demonstrating increased LV wall thickness (but not LV mass) measured by echo was associated with plasma leptin independent of BMI or waist/hip ratio (P = 0.001)	Pro-hypertrophic
	Perego et al[29]	Study of 31 obese subjects undergoing gastric bypass surgery demonstrated leptin was independently associated with LV mass (β = 10.66, P = 0.001). One year after surgery, decrease in LV mass only correlated with the decrease in leptin levels (P = 0.01)	Pro-hypertrophic
	Lieb et al[40]	Cross-sectional analysis of 432 aged (> 70 yr) participants in the Framingham Heart Study demonstrated leptin concentrations were inversely correlated with LV mass (β = -0.134, P = 0.02), left atrial size (β = -0.131, P = 0.04) and LV wall thickness (β = -0.134, P = 0.02) measured by echo	Anti-hypertrophic
	Martin et al[41]	In 1464 MESA Study participants who underwent cardiac magnetic resonance imaging, a 1-SD increment in leptin was associated with smaller LV mass (β = -4.66%, P < 0.01), LV volume (β = -5.87, P < 0.01), and reduced odds ratio for presence of LVH (OR = 0.65, P < 0.01) after adjustment for age, gender, race, height, and weight	Anti-hypertrophic

LVH: Left ventricular hypertrophy; BMI: Body mass index.