Experimental design for the first experiment. (A) Schematic representation of the cross-over experimental design. Photoperiodic treatments are given in the upper part. 3 weeks before the first day of injection (D0) the ewes were housed under LP. During each day of injection (D0 and D10 for metformin; D42 and D52 for AICAR) LP was replaced by DD. (B) Bleeding protocol operated during DD, each thick depicts one sample. Thick arrow depict the clock time for the administration of the injection (19:00). Serial sampling period began 1 hr before injection and lasted for 7 hrs (from 17:00 to 00:00 during the injection of metformin and adjusted from 18:00 to 01:00 for the injection of AICAR). Thin arrows depict theoretical lightning transitions. See text for more details.