Abstract: The neuropeptide galanin (GAL) is involved in the control of hormone secretion, nociception, feeding
behavior, attention, learning and memory. The anatomical localization of galanin receptors in the brain
has been described using autoradiography and immunohistochemistry, but both techniques are limited
by the availability of specific radioligands or antibodies. Functional autoradiography provides an alternative
method by combining anatomical resolution and information of the activity mediated by G-protein
coupled receptors. The present study analyzes the functional GAL receptors coupled to Gi/o-proteins in
human and rat brain nuclei using [35S]GTPcS autoradiography.
The results show the anatomical distribution of Gi/o-proteins activated by GAL receptors that trigger
intracellular signaling mechanisms. The activity mediated by GAL receptors in human and rat brain
showed a good correlation of the net stimulation in areas such as spinal cord, periaqueductal gray, putamen,
CA3 layers of hippocampus, substantia nigra and diverse thalamic nuclei.
The functional GAL receptors coupled to Gi/o-proteins showed a similar pattern for both species in most
of the areas analyzed, but some discrete nuclei showed differences in the activity mediated by GAL, such
as the ventroposteromedial thalamic nucleus, or areas that regulate learning and memory processes in
the hippocampus. Taken into consideration the present results, the rat could be used as an experimental
model for the study of the physiological role of GAL-mediated neurotransmission and the modulation of
GAL receptors activity in the human CNS.
