High-dose dietary supplementation of vitamin A induces brain-derived neurotrophic factor and nerve growth factor production in mice with simultaneous deficiency of vitamin A and zinc.

Marginal vitamin A and zinc (Zn) deficiency often co-exist in many populations. Vitamin A plays a trophic role in brain and is important for its development. We investigated effects of dietary supplementation of vitamin A on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) production in mice depleted for vitamin A and Zn. After 3 months' feeding with a low vitamin A and Zn (LVA-LZ) diet, mice were divided into two groups and replenished with either normal or high vitamin A with low Zn diet for an additional 2 months. Levels of BDNF and NGF were measured from extracts of hippocampus, cortex and cerebellum at the end of the third and fifth months. The LVA-LZ group tended to show decreased amounts of the BDNF and NGF, while animals supplemented with high vitamin A along with Zn deficiency had high BDNF and NGF concentrations. From these results, we conclude that vitamin A may increase BDNF and NGF levels.

Increased nerve growth factor by zinc supplementation with concurrent vitamin A deficiency does not improve memory performance in mice.

We investigated the effects of dietary supplementation of zinc (Zn) with or without vitamin A (Vit. A), to elucidate any cross activity between the two micronutrients, on memory and nerve growth factor (NGF) production in ddY male mice depleted for the two elements. After 3 mo-feeding with a Zn and Vit. A deficient (VAD) diet, mice were divided into three groups and replenished with normal Zn with VAD diet (NZ-VAD), high Zn with VAD diet (HZ-VAD) or normal Zn + normal Vit. A (NZ-NVA) for additional 2 mo. One more group was made and given the normal diet for the same period (Control group). Levels of NGF were measured from extracts of hippocampus, cerebellum and cortex at the end of the 3rd and 5th month. In addition, a radial arm maze task was performed at the end of the 5th month. The two Zn supplemented groups (NZ-VAD and HZ-VAD) tended to show high NGF concentration but memory was not improved. However, improved memory was observed in the NZ-NVA group. From these results we concluded that Zn may increase NGF; however, memory was improved only when Vit. A was sufficient.

Lack of nociceptin receptor alters body temperature during resting period in mice.

The role of nociceptin (NOC) receptor on body core temperature (Tcore) control was examined using NOC receptor knockout mice. In homozygote NOC receptor-knockout, wild-type, and control C57BL/6J and 129/SV mice, Tcore was continuously recorded under 12:12 h light:dark (LD) and conditions of constant darkness (DD). The Tcore values during the resting period were higher in the NOC receptor-knockout mice than in both wild-type and control mice under both LD and DD conditions. Spontaneous activity during the resting period and plasma cortisol levels were not different between the NOC receptor-knockout and control mice. The findings herein indicate that the NOC receptor is involved in the control of Tcore during the resting period and is independent of light, physical activity and/or cortisol regulation.