Figure 5.

Increased dose of LDN or varied the time of LDN exposure did not cause sustained changes in POMC neuron intrinsic excitability or β-endorphin plasma concentrations. A, Resting membrane potential did not change after 3-, 7-, or 12-d LDN treatment at either 0.1 or 3 mg/kg. B, Varying the time or dose of LDN treatment also did not change POMC neuron action potential threshold or (C) action potential frequency. D, LDN treatment did not systematically alter β-endorphin concentrations in plasma, although a transient decrease in β-endorphin concentration was observed with 0.1 mg/kg at 3 d of treatment. Number of mice used for each group in the β-endorphin group are as follows: 3 d saline = 3, 0.1 mg/kg LDN = 3, 3 mg/kg LDN = 4; 7 d saline = 7, 7 d 0.1 mg/kg = 8, 7 d 3 mg/kg = 4; 12 d saline = 5, 12 d 0.1 mg/kg LDN = 4, 12 d 3 mg/kg = 4; *p < 0.05.