Recabarren MP, Valdes JL, Seron-Ferre M, Torrealba F (2003) Tuberomammillary nucleus lesion decreases the anticipatory events induced by restricted feeding in rats. Neuroscience 2003 Abstracts 510.19. Society for Neuroscience, New Orleans, LA.
Summary: Our previous studies indicate that the histamine-containing neurons of the tuberomammillary nucleus (TMN) become active in anticipation to feeding time in rats under a restricted feeding schedule. To assess the role of the TMN in this anticipatory activity in rats, we lesioned the TMN bilaterally with stereotaxic injections of 50ng ORX-SAP (Advanced Targeting System, CA). We analyzed the locomotor activity, core temperature and the feeding frequency exhibited by these animals during a restricted feeding protocol, where food was available between 10:00 h and 12:00 h for at least 2 weeks. Rats were implanted in the abdominal cavity with telemetric sensors (Minimitter, OR) to measure locomotor activity and core temperature. During the whole experiment rats were maintained in individual cages and under controlled photoperiod of 12 hours light and 12 hours dark, light were on at 07:00 h. We analyzed the 3 hours preceding food arrival. We checked the extent of TMN destruction by immunostaining the brain sections with antibody against adenosine diaminase (ADA), which colocalize with histaminergic neurons in the TMN. Control rats were subjected to the same procedures except for the injection of the ORX-SAP toxin. Results: Lesion rats showed a significant decrease in the number of ADA-ir neurons in the TMN, as well as a decreased anticipatory activity under restricted feeding in comparison with control rats. Lesion rats although awake before food arrival, were less eager to feed compared to controls, as assessed by food bin approaches. Control rats were slightly more active than lesion rats during restriction. In conclusion, the functional integrity of the TMN is required for the full expression of the anticipatory events that are stimulated by a restricted feeding schedule.
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