Localization of calcium-binding protein (calretinin, 29 kD) in the brain and pituitary gland of teleost fish: an immunohistochemical study.

Immunocytochemical techniques were used to investigate the distribution of calretinin in the brain and pituitary gland of the hardhead catfish Arius felis. Calretinin immunoreactive neurons were found in the telencephalon (lateral nucleus of ventral telencephalic area), diencephalon (around the medial forebrain bundle, lateral tuberal nucleus, central pretectal nucleus, posterior periventricular hypothalamic nucleus, medial preglomerular nucleus, diffuse nucleus of the inferior lobe), mesencephalon (nucleus of the medial longitudinal fascicle, ventral nucleus of the semicircular torus), cerebellum (valvula cerebelli, eurydendroid cells) and rhombencephalon (secondary gustatory nucleus, isthmic nucleus, trigeminal motor nucleus, medial auditory nucleus of the medulla, medial and inferior reticular formation, anterior, descending, posterior and tangential octaval nuclei). Calretinin-labeled fibers were observed in the optic nerve and at the levels of the central pretectal nucleus, the nucleus of the medial longitudinal fascicle, the ventral nucleus of the semicircular torus, the secondary gustatory nucleus, the trigeminal motor nucleus, the eurydendroid cells, the medial auditory nucleus of the medulla and the octaval nucleus. For the first time, we are reporting on calretinin-positive cells in the rostral and proximal pars distalis of the adenohypophysis. Although, it seems speculatory, calretinin-expressing cells in the pituitary gland may be involved in hormonal regulation and hence, calretinin might play a significant role in governing hypophysial functions in fishes. Our results suggest that calretinin shows species-specific variations also among the teleost fish, similar to mammals.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity in the brain of a cichlid fish, with remarkable findings in the entopeduncular nucleus: a histochemical study.

In the entire brain of the African cichlid fish, Haplochromis burtoni, nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity was visualized histochemically in fewer nuclei compared to other teleost fish. Intensively labeled perikarya were found in the ventral hypothalamic area, the nucleus of the medial longitudinal fascicle, the nucleus of the midbrain tegmentum, the nucleus of the lateral longitudinal fascicle, the trigeminal motor nucleus and the octavolateral area. Compared to other NADPH-d labeled nuclei in the brain, we saw an unusual localization of NADPH-d activity in the rostral, dorsal, ventral and caudal part of the entopeduncular nucleus. Additionally, some isolated perikarya of different morphological appearance were found at the levels of the preglomerular nucleus, the diffuse nucleus of the lateral torus and the lateral longitudinal fascicle. A widespread distribution of labeled fibers was identified throughout the brain. The remarkable NADPH-d activity, particularly in the entopeduncular nucleus, differs significantly from the existing data on other teleosts. Taking into account the sensory functions of the entopeduncular nucleus described in other vertebrates, the massive NADPH-d activity in this nucleus may indicate an important role of NADPH-d in the modulation of sensory functions.

Antigenic compartmentation of the primate and tree shrew cerebellum: a common topography of zebrin II in Macaca mulatta and Tupaia belangeri.

Despite the apparent uniformity in cellular composition of the adult cerebellar cortex, functional, anatomical, mutational and molecular maps all reveal a complex topography underlying the relatively simple architecture. In particular, zebrin II, a polypeptide antigen identified as aldolase C, is restricted to a subset of Purkinje cells that form a symmetrical and reproducible array of zones and stripes. The vermis of the well-studied rodent cerebellar cortex is divided into four transverse zones--anterior ( approximately lobules I-V), central ( approximately lobules VI and VII), posterior ( approximately lobule VIII) and nodular ( approximately lobules IX and X). Each transverse zone is further subdivided mediolaterally into parasagittal stripes. To gain insight into the evolution of cerebellar compartmentation, the pattern of zebrin II expression has been compared between the primate Macaca mulatta and the tree shrew Tupaia belangeri, and the results related to previous findings from other species. Although the somata of most Purkinje cells in the Macaca cerebellum express zebrin II, parasagittal stripes can still be delineated owing to the alternating high and low zebrin II immunoreactivity in the dendrites. In the macaque vermis, a complex set of zebrin II parasagittal compartments is found in all transverse zones. Unlike in rodents, in which uniform expression domains interrupt heterogeneous zones, zebrin II parasagittal stripes in the macaque cerebellum are seen throughout the vermis. In Tupaia, the parasagittal pattern of zebrin II expression also reveals a striking array of stripes in all lobules. The data suggest that cerebellar compartmentation in Tupaia belangeri more closely resembles that of primates than it does rodents or lagomorphs.

Localization of the neuronal form of nitric oxide synthase (bNOS) in the diencephalon and pituitary gland of the catfish, Synodontis multipunctatus: an immunocytochemical study.

The distribution of the neuronal form of nitric oxide synthase (bNOS) was investigated in the brain and pituitary gland of the catfish, Synodontis multipunctatus. Immunoreactive neurons were found mainly in the nucleus praeopticus periventricularis, the parvocellular and supraoptic subdivisions of the nucleus praeopticus, the nucleus recessus lateralis and the nucleus recessus posterioris. In addition, some scattered bNOS labeled somata were noted in the dorsal hypothalamic area. A few positive cells in the adenohypophysis and some reactive fibers in the pituitary stalk were also seen. Our results are compatible with the notion that the cells expressing bNOS in the diencephalon and hypophysis are involved in the control of hormone regulation. Moreover, the presence of bNOS positive cells in the rostral pars distalis of the pituitary gland supports a role of nitric oxide in osmoregulation.

Calretinin immunoreactivity in the prenatally developing olfactory systems of the tree shrew Tupaia belangeri.

The prenatal patterns of calretinin immunoreactivity were studied in the olfactory systems of Tupaia belangeri. We investigated the peripheral and primary central parts of the vomeronasal system and of the main olfactory system from the 19th to the 43rd (last) day of gestation and compared the findings with the known calretinin immunoreactivity patterns in adult T. belangeri and the published data on other mammals. The onset of calretinin immunoreactivity was noted in the main olfactory system on the 23rd day of gestation and, in the vomeronasal system, on the 25th day of gestation: single precursors of receptor cells with calretinin immunoreactive perikarya and processes were observed in both epithelia. Their neuronal identity was proven by olfactory marker protein immunoreactivity. On the 42nd day of gestation, almost all receptor cells and nerve fibers, many interneurons and projecting cells were calretinin immunoreactive in the main olfactory and in the vomeronasal systems. In contrast to the intensive calretinin labeling previously observed in virtually all vomeronasal epithelial cells of adult T. belangeri, among developing receptor cells a population of intensively labeled, basally located perikarya was distinguishable from a population of less intensively stained, more apically located ones. In the main olfactory epithelium of fetal T. belangeri, calretinin immunoreactive receptor cells occurred in the middle layers. Whereas in the vomeronasal sensory epithelium differently reacting layers of receptor cells might represent the two known subfamilies of receptor cells, in the main olfactory epithelium the differing calretinin expression in the layers of the epithelium, most probably, did not reflect known subfamilies of odour receptor cells. Transiently, ectopic calretinin immunoreactive receptor cells were observed in the future non-sensory epithelium of the vomeronasal organ.