Figure 2.

The effects of intracerebroventricular injection of interleukin- (IL-) 1β (50 μg/animal) or Ringer's solution (50 μL) on melatonin concentration in ewes taken during the short night (SN, May/June) and long night (LN, November/December) photoperiods. Experiments started one hour after sunset. (a) presents the temporal patterns of the mean concentration of circulating melatonin (n = 6 animals per group) in 15 min samples. (b) depicts the mean (± SEM; n = 6 animals per group) concentrations of melatonin for the period after IL-1β or Ringer's solution treatment (1 to 4 h) of ewes during the SN and LN photoperiods. Different capital letters indicate significant (P < 0.05) differences based on a two-way ANOVA followed by Tukey's post hoc test.