Distribution of somatostatin immunoreactivityin the brain of the snake Bothrops jararaca

ABSTRACT

The distribution of perikarya and fibers containing somatostatin was studied in the brain of the snake Bothrops jararaca by means ofimmunohistochemistry using an antiserum against synthetic somatostatin. Immunoreactive perikarya and fibers were localized in telencephalic,diencephalic and mesencephalic areas. In the telencephalon, numerous immunoreactive perikarya were found in the medial,dorsomedial, dorsal and lateral cortex, mainly in the deep plexiform layer, less so in the cellular layer, but not in the superficial plexiformlayer. Immunoreactive perikarya were also observed in the dorsal ventricular ridge, the nucleus of the diagonal band of Broca, amygdaloidcomplex, septum and lamina terminalis. In the diencephalon, labelled cells were observed in the paraventricular, periventricularhypothalamic and in the recessus infundibular nuclei. In the mesencephalon, immunoreactive perikarya were seen in the mesencephalicreticular formation, reticular nucleus of the isthmus and torus semicircularis. Labelled fibers ran along the diencephalic floor and theinner zone of the median eminence, and ended in the neural lobe of the hypophysis. Other fibers were observed in the outer zone ofthe median eminence close to the portal vessels and in the septum, lamina terminalis, retrochiasmatic nucleus, deep layers of the tectum,periventricular gray and granular layer of the cerebellum. Our data suggest that somatostatin may function as a mediator of adenohypophysialsecretion as well as neurotransmitter and/or neuromodulator which can regulate the neurohypophysial peptides in the snakeB. jararaca(