IMMUNOCYTOCHEMICAL LOCALIZATION OF CORTICOTROPIN-RELEASING FACTOR IN THE BRAIN OF THE TURTLE, MAUREMYS-CASPICA

Brain sections of the turtle, Mauremys caspica were studied by means o f an antiserum against rat corticotropin-releasing factor. Immunoreact ive neurons were identified in telencephalic, diencephalic and mesence phalic areas such as the cortex, nucleus caudatus, nucleus accumbens, amygdala, subfornical organ, paraventricular nucleus, hypothalamic dor solateral aggregation, nucleus of the paraventricular organ, infundibu lar nucleus, pretectal nucleus, periventricular grey, reticular format ion and nucleus of the raphe. Many immunoreactive cells located near t he ependyma were bipolar, having an apical dendrite that contacted the cerebrospinal fluid. Immunoreactive fibers were seen in these locatio ns and in the lamina terminalis, lateral forebrain bundle, supraoptic nucleus, median eminence, neurohypophysis, tectum opticum, torus semic ircularis and deep mesencephalic nucleus. Parvocellular bipolar immuno reactive neurons from the paraventricular and infundibular nuclei proj ected axons that joined the hypothalamo-hypophysial tract and reached the outer zone of median eminence, and the neural lobe of the hypophys is where immunoreactive fibers terminated close to intermediate lobe c ells. From these results it can be concluded that, as in other vertebr ates, corticotropin-releasing factor in the turtle may act as a releas ing factor and, centrally, as a neurotransmitter or neuromodulator.