Immunocytochemical localization of corticotropin-releasing factor in the brain of the turtle, Mauremys caspica

Abstract

Brain sections of the turtle, Mauremys caspica were studied by means of an antiserum against rat corticotropin-releasing factor. Immunoreactive neurons were identified in telencephalic, diencephalic and mesencephalic areas such as the cortex, nucleus caudatus, nucleus accumbens, amygdala, subfornical organ, paraventricular nucleus, hypothalamic dorsolateral aggregation, nucleus of the paraventricular organ, infundibular nucleus, pretectal nucleus, periventricular grey, reticular formation and nucleus of the raphe. Many immunoreactive cells located near the ependyma were bipolar, having an apical dendrite that contacted the cerebrospinal fluid. Immunoreactive fibers were seen in these locations and in the lamina terminalis, lateral forebrain bundle, supraoptic nucleus, median eminence, neurohypophysis, tectum opticum, torus semicircularis and deep mesencephalic nucleus. Parvocellular bipolar immunoreactive neurons from the paraventricular and infundibular nuclei projected axons that joined the hypothalamo-hypophysial tract and reached the outer zone of median eminence, and the neural lobe of the hypophysis where immunoreactive fibers terminated close to intermediate lobe cells. From these results it can be concluded that, as in other vertebrates, corticotropin-releasing factor in the turtle may act as a releasing factor and, centrally, as a neurotransmitter or neuromodulator.

Distribution and Acute Stressor‐Induced Activation of Corticotrophin‐Releasing Hormone Neurones in the Central Nervous System of Xenopus laevis

“…The distribution of CRH‐ir in the telecephalon of X. laevis is consistent with previous results obtained in Rana tigrina and Rana ridibunda (13, 15). We also identified CRH‐ir positive cells and fibres in the amygdala, which is in agreement with previous reports in frogs (11, 15), reptiles (38–40), birds (41, 42) and mammals (43). In the mesencephalon of other amphibian species, CRH‐ir was reportedly restricted to the interpeduncular nucleus and tectal regions (9, 15).…”

“…Although this pattern of CRH‐ir has not been described in other amphibian species, CRH is widely expressed in the cerebellum (all three layers) and in the locus coeruleus in mammals (41, 46, 47). In support of our findings in X. laevis , the torus semicirculus and tectal regions are also regions of CRH‐ir in other vertebrates [reptiles (39); birds (41); mammals (48)]. Reticular locations and cranial nerves have not previously been shown to be CRH immunoreactive in amphibian species; however, a number of other vertebrate species including reptiles (38, 40) birds (41, 44, 49) and mammals (43, 46, 47) exhibit CRH‐ir in these areas.…”

Corticotropin-releasing factor distribution in the brain of the brown anole lizard

“…Similar to what is seen in these other reptile species, brown anoles were found to possess CRF cells and fibers in the subfornical organ, paraventricular nucleus of the hypothalamus, and cortical regions [9][10][11]. capsica were in a location that is more similar to our findings, within posterior dorsal ventricular ridge [10], whereas those in the snake N. maura are shown as more likely within the medial amygdala region [11].…”

“…This study examined the brains of three male brown anoles that were part of a previous study examining Ile 8 -oxytocin (mesotocin) colocalization with CRF in the hypothalamus [15]. Although we did not examine female brown anole brains, results from CRF studies in other reptiles have found no sex differences in intensity or distribution of signal [9][10][11]. Animals were housed in a terrarium (30.…”

Embryonic Origin of the Islet1 and Pax6 Neurons of the Chicken Central Extended Amygdala Using Cell Migration Assays and Relation to Different Neuropeptide-Containing Cells

“…Thus, the presence of enkephalinergic cells in the EAce appears to be a common feature of the EAce in tetrapods, but amphibians seem to lack two of the subtypes of enkephalinergic neurons present in mouse, chicken and possibly reptiles: those suggested to derive from the LGEd/Std and those suggested to derive from the PO. On the other hand, CRF neurons (apparently derived from the LGEv/Stv in mouse and chicken) have not been found in the EAce region of turtles [López-Avalos et al, 1993], while data in anurans are inconsistent (not found in the toad [Matsuda et al, 2010] but found in a similar pattern to that in chicken in Xenopus laevis [Yao et al, 2004]). Moreover, NT cells have not been found in the EAce of either frogs or lacertid lizards [Bello et al, 1994].…”