INVESTIGADORES
DIONISIO Leonardo Raul
congresos y reuniones científicas
Título:
Characterization of a neuronal-like GABAergic system in human lymphocytes
Autor/es:
DE ROSA, M.J.; DIONISIO, L.; BOUZAT, C.; ESANDI, M.C.
Lugar:
San Diego, CA
Reunión:
Congreso; 40th Annual Meeting Society for Neuroscience; 2010
Institución organizadora:
Society for Neuroscience
Resumen:
GABA is an
ubiquitous neurotransmitter in the central nervous system. The goal of this
study was to determine if components of the GABAergic system are expressed in
lymphocytes and whether their presence had any functional significance.
Using RT-PCR
we analyzed expression of mRNA of different components of this system in resting
and mitogen activated lymphocytes: i) GAD65 and GAD67, two isoforms of the
enzyme that synthetizes GABA; ii) VIAAT, the vesicular
protein involved in GABA store; iii) GABA transporters (GAT1-2); iv) GABA-T,
the enzyme that catabolizes GABA; v) alpha (a1-6) and rho2 subunits that conform GABAA receptors.
The
functionality of the transporters was evaluated by measuring uptake of
radioactive GABA. The results demonstrated that the uptake of GABA is
significantly higher in activated lymphocytes than in resting ones. In addition
we performed immunocytochemistry to detect VIAAT protein and real time PCR to
quantify the mRNA levels of GABA-T. We observed upregulation of VIAAT and GABA-T upon mitogen
stimulation.
To determine if GABA subunits assemble into
functional channels, we performed whole-cell recordings in activated
lymphocytes. GABA and Muscimol, a specific agonist for ionotropic
GABA receptors, elicits macroscopic
currents in about 20-30% of the cells that exhibits different kinetic
properties. These experiments show that lymphocytes express functional GABAA
channels, and suggest that different types of GABAA receptors are
present. Finally, using [3H]thymidine
incorporation, we established that GABA is able to modulate negatively lymphocyte
proliferation. Muscimol, similarly to GABA, inhibits lymphocyte proliferation. These
data demonstrate that ionotropic GABA receptors are the main modulators of the
immune-suppressive effects of GABA.
Our results revealed
that lymphocytes have most of the essential components needed to constitute a
non-neuronal GABAergic system. Pharmacological modulation of this system may
provide new approaches for regulation of T cell response. Furthermore,
elucidation of its function will contribute to clarify the interactions between
the nervous and immune systems.