GAD1 and its potential relationship with NeuroD1 in the rat pineal gland.

S. BENITEZ; A.E. CASTRO; V. ORTIZ MALDONADO; L.E. SAVASTANO; M.R. FITT; E.M. MUÑOZ

Huerta Grande, Córdoba.

Congreso; XXVI Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2011

Sociedad Argentina de Investigación en Neurociencias

There is much controversy regarding the existence and role of an intrinsic GABAergic system in the pineal gland. Microarray analysis ofpineal glands from neonatal NeuroD1 KO mice identified Gad1 as the most up-regulated gene. Its product, the enzyme glutamic acid decarboxylase 1 (GAD1), converts glutamic acid into gamma-aminobutyric acid(GABA). In our laboratory, we are characterizing the ontogeny of this and other components of the gabaergic system and their relationship with the differentiationfactor NeuroD1 in the rat pineal gland. The 67 kDa GAD1 protein was identified as a unique band in cytoplasmic pineal extracts via Western blot using a specific monoclonal antibody. GAD1 immunoreactivity was mainly observed in a few NeuroD1-negative astrocyte-like interstitial cells. The expression of GAD1 in pinealocytes is still under investigation, as its levels appear to be below the detection limits of standard IHC. The bilateral removal of the superior cervical ganglia did affect pineal GAD1 expression, and did increase the vimentin-positive cell population. Interestingly, a subpopulation of these glia-like cells was negative for nuclear NeuroD1. Further studies are being performed to elucidate the role of GABAergic innervation and intrinsic GABAergic cells in the pineal ontogeny.