The effect of β-endorphin (10−8 M;
β-End), naltrexone (10−8 M; Nalt), NP (600 μM), and
their combinations on LHRH release from MBH incubated in
vitro. In this and subsequent figures, the height of the column
represents the mean and the vertical line represents 1 SEM.
Significantly different from control: ∗, P <
0.05, ∗∗, P < 0.01; ∗∗∗,
P < 0.001. a, Not significantly different from
other columns labeled with a. b, Significantly different from columns
labeled with a. n = 8 for each column.