L-glutamine supplementation during the lactation period facilitates cortical spreading depression in well-nourished and early-malnourished rats.
OBJECTIVE
Glutamine (Gln) participates in the so-called "brain glutamine-glutamate cycle" and therefore it is likely to influence brain excitability. Here we investigated, in weaned well-nourished and early-malnourished rats, the effects of previous Gln oral supplementation, during the brain development period, on cortical spreading depression (CSD), an excitability-related brain phenomenon.


METHODS
Male Wistar (W) suckling rat pups, well-nourished (litters with 6 pups) and malnourished (M) during lactation (by increasing the litters to 12 pups), received Gln (500 mg/kg/day) by gavage during postnatal days 7 to 27. At 30-40 days of life, they were submitted to a cortical spreading depression (CSD) recording session during 4 h, on 2 cortical parietal points of the right hemisphere. CSD velocity propagation was calculated from the time required for a CSD wave to cross the inter-electrode distance.


RESULTS
In both nutritional condition, Gln rats presented higher (p<0.05) CSD propagation velocities (W-Gln, 4.22+/-0.23; M-Gln, 4.51+/-0.27 mm/min), as compared to water-treated controls (W-Wa, 3.77+/-0.21; M-Wa, 4.15+/-0.18 mm/min). This water control group did not differ from a naive control group that was not submitted to the gavage procedure. A fourth group, treated with a "placebo amino acid" (glycine), also displayed CSD velocities in the control range.


CONCLUSIONS
The results indicate that Gln supplementation during brain development facilitates cortical spreading depression propagation, as judged by the higher CSD velocities, and this effect is not abolished by malnutrition. Data support the idea of Gln-related changes in brain excitability, during neural development.
de Lima
Denise Sandrelly Cavalcanti
DS
Department of Nutrition, Universidade Federal de Pernambuco, 50670901 Recife, PE, Brazil.
Maia
Luciana Maria Silva de Seixas
LM
Barboza
E'lida de Andrade
Ede A
Duarte
Raísa de Almeida
Rde A
de Souza
Laís Santos
LS
Guedes
Rubem Carlos Araújo
RC
D000284:Administration, Oral; D000818:Animals; D000833:Animals, Suckling; D001921:Brain / Q000187:drug effects* / Q000254:growth & development / Q000503:physiopathology; D013181:Cortical Spreading Depression / Q000187:drug effects* / Q000502:physiology; D004569:Electroencephalography; D005973:Glutamine / Q000008:administration & dosage*; D007774:Lactation / Q000502:physiology*; D008297:Male; D044342:Malnutrition / Q000150:complications / Q000503:physiopathology*; D051381:Rats
D005973:Glutamine