Neonatal administration of goat whey modulates memory and cortical spreading depression in rats previously suckled under different litter sizes: Possible role of sialic acid

Abstract

Objectives: Goat whey, a usually discarded byproduct from goat cheese manufacturing, is a good source of sialic acid (SA), an oligosaccharide that is involved in processes such as memory and brain excitability. Here, we investigated in rats the effect of dried goat whey (DGW) on memory and the brain excitability-dependent phenomenon known as cortical spreading depression (CSD). We also provide evidence for the involvement of SA in this effect. In addition, we tested animals under unfavorable suckling conditions to evaluate whether nutritional deficiency would modulate DGW action.

Methods: Wistar rats were suckled in litters with 9 and 15 pups (groups L₉ and L₁₅, respectively). From postnatal (P) days 7–14, the animals received per gavage 17.45 g of DGW/kg/day, or SA (20 mg/kg/day or 100 mg/kg/day). At P28-30, we tested the animals’ memory in the object recognition paradigm. At P35-45 we recorded CSD and analyze its velocity of propagation, amplitude, and duration.

Results: In the object recognition test, the L₁₅ DGW-treated rats performed better than the L₁₅-controls. The L₁₅ rats displayed higher CSD velocities compared with L₉ groups. The DGW and SA groups exhibited higher CSD velocity than the naïve- and saline-treated controls, regardless the lactation status (P < 0.05).

Discussion: Our results documented a novel effect of DGW on memory and CSD. SA dose-dependently facilitated CSD, suggesting its involvement on the DGW action. DGW is considered a potential supplement to improve brain development and function in malnourished children, and this shall be further translationally investigated.

Keywords:

• Goat whey
• Sialic acid
• Spreading depression
• Memory
• Brain
• Cortical excitability
• Malnutrition
• Oligosaccharide

Acknowledgements

The authors thank Dr Marta Suely Madruga for providing the spray drier facility, Dr Ariosvaldo Nunes de Medeiros for providing the goat milk, and the financial support from CNPq (Edital agronegócio 403020/2013-0 and Edital universal 445101/2014-8), CAPES (AUXPE–CIMAR 1990/2014), and MCT/FINEP/CT-INFRA-–(PROINFRA–01/2008). R.C.A. Guedes is a research fellow from CNPq (No. 303636/2014-9).