Brain-derived neurotrophic factor enhances spontaneous sleep in rats and rabbits

Various growth factors are involved in sleep regulation. Brain-derived neur otrophic factor (BDNF) belongs to the neurotrophin family; it and its recep tors are found in normal brain. Furthermore, cerebral cortical levels of BD NF mRNA have a diurnal variation and increase after sleep deprivation. Ther efore, we investigated whether BDNF would promote sleep. Twenty-four male S prague-Dawley rats (320-380 g) and 25 male New Zealand White rabbits (4.5-5 .5 kg) were surgically implanted with electroencephalographic (EEG) electro des, a brain thermistor, and a lateral intracerebroventricular cannula. The animals were injected intracerebroventricularly with pyrogen-free saline a nd, on a separate day, one of the following doses of BDNF: 25 or 250 ng in rabbits; 10, 50, or 250 ng in rats. The EEG, brain temperature, and motor a ctivity were recorded for 23 h after the intracerebroventricular injections . BDNF increased time spent in non-rapid eye movement sleep (NREMS) in rats and rabbits and REMS in rabbits. Current results provide further evidence that various growth factors are involved in sleep regulation.