IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
artículos
Título:
Transient and regional changes in GAP-43 and SNARE protein immunoreactivity in developing rat synaptic terminals after sublethal postnatal hypoxia
Autor/es:
VALDÉZ, SR; PATTERSON, SI; EZQUER, ME; TORRECILLA, M; SELTZER, AM
Revista:
SYNAPSE
Referencias:
Año: 2007 vol. 61 p. 124 - 137
ISSN:
0887-4476
Resumen:
We assessed immunoreactivity (IR) in the cerebral cortex (CC), hippocampus
(Hipp), and striatum (ST) of a growth-associated protein, GAP-43, and of proteins
of the synaptic vesicle fusion complex: VAMP-2, Syntaxin-1, and SNAP-25 (SNARE proteins)
throughout postnatal development of rats after submitting the animals to acute
global postnatal hypoxia (6.5% O2, 70 min) at postnatal day 4 (PND4). In the CC only the
IR of the SNARE protein SNAP-25 increased significantly with age. The hypoxic animals
showed the same pattern of IR for SNAP-25, although with lower levels at PND11, and
also a significant increase of VAMP-2. SNAP-25 (control): PND11 P < 0.001 vs. PND18,
25, and 40, SNAP-25 (hypoxic): P < 0.001 vs. PND18, 25, and 40; VAMP-2 (hypoxic): P <
0.05 PND11 vs. PND18, and P < 0.01 vs. PND25 and PND40; one-way ANOVA and Bonferroni
post-test. In the Hipp, SNAP-25 and syntaxin-1 increased significantly with age,
reaching a plateau at PND25 through PND40 in control animals (one-way ANOVA: syntaxin-
1: P ¼ 0.043; Bonferroni: NS; SNAP-25: P ¼ 0.013; Bonferroni: P < 0.01 PND11 vs.
PND40). Hypoxic rats showed higher levels of significance in the one-way ANOVA than
controls (syntaxin-1: P = 0.009; Bonferroni: P < 0.05 PND11 vs. PND25 and P < 0.001
PND11 vs. PND40). In the ST, GAP-43 differed significantly among hypoxic and control
animals and the two-way ANOVA revealed significant differences with age (F = 3.23;
P = 0.037) and treatment (F = 4.84; P = 0.036). VAMP-2 expression also reached statistical
significance when comparing control and treated animals (F = 6.25, P = 0.018) without
changes regarding to age. Elevated plus maze test performed at PND40 indicated a
lower level of anxiety in the hypoxic animals. At adulthood (12 weeks) learning, memory
and locomotor abilities were identical in both groups of animals. With these results, we
demonstrate that proteins of the presynaptic structures of the ST are sensitive to acute
disruption of homeostatic conditions, such as a temporary decrease of the O2 concentration.
Modifications in the activity of these proteins could contribute to the long term
altered responses to stress due to acute hypoxic insult in the neonatal period.