Distribution of beacon immunoreactivity in the rat brain.

Beacon is a novel peptide isolated from the hypothalamus of Israeli sand rat. In the present study, we determined the distribution of beacon in the rat brain using immunohistochemical approach with a polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47-73). The hypothalamus represented the major site of beacon-immunoreactive (IR) cell bodies that were concentrated in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON). Additional immunostained cells were found in the septum, bed nucleus of the stria terminalis, subfornical organ and subcommissural organ. Beacon-IR fibers were seen with high density in the internal layer of the median eminence and low to moderate density in the external layer. Significant beacon-IR fibers were also seen in the nucleus of the solitary tract and lateral reticular formation. The beacon neurons found in the PVN were further characterized by double label immunohistochemistry. Several beacon-IR neurons that resided in the medial PVN were shown to coexpress corticotrophin-releasing hormone (CRH) and most labeled beacon fibers in the external layer of median eminence coexist with CRH. The topographical distribution of beacon-IR in the brain suggests multiple biological activities for beacon in addition to its proposed roles in modulating feeding behaviors and pituitary hormone release.

Cold-stress induced the modulation of catecholamines, cortisol, immunoglobulin M, and leukocyte phagocytosis in tilapia.

The concentrations of norepinephrine in hypothalamus and norepinephrine and epinephrine in head kidney were significantly decreased in treated tilapia (Oreochromis aureus) during the time course of cold exposure (12 degrees) as compared to the control (25 degrees). The elevation of norepinephrine and epinephrine in plasma was detected earlier than that of cortisol in cold-treated tilapia. Phagocytic activity of leukocytes and the levels of plasma immunoglobulin M (IgM) were depressed in cold-treated tilapia as compared to the control group. Handling stress in the control (25 degrees) also resulted in increased plasma cortisol and decreased plasma IgM levels but not phagocytic activity. In vitro cortisol suppressed leukocyte phagocytosis in a dose (10(-12) to 10(-4) M)-dependent manner. Adrenergic agonist (phenylephrine and isoproterenol) had a significant suppression of phagocytosis only at the highest dose (10(-4) M). No effect on phagocytosis was detected in the treatment with norepinephrine and epinephrine. A combination of cortisol and isoproterenol (0.1 mM) had an additive effect in the suppression of phagocytosis. It is concluded that the cold stress modulated the changes of catecholamines and cortisol and further depressed phagocytic activity and antibody levels in tilapia. Cortisol could play a main and important role in the down-regulation of phagocytic activity. Adrenergic agonists also could interact with cortisol to further suppress immunity in tilapia.

Changes in immunoreactivity to anti-cGnRH-I and -II are associated with photostimulated sexual status in male quail.

In sexually active males exposed to long-day (LD) photoperiod, perikarya in the olfactory bulb, lobus parolfactorius, n. accumbens, and preoptic region were immunoreactive (ir) to an antiserum against gonadotropin-releasing hormone (anti-cGnRH-I), and a cluster of ir-perikarya was found in the caudal-most septal area. Ir-perikarya in these brain areas of sexually inactive short-day (SD) males were located within more discrete areas than those in LD brain, which were more scattered in appearance. Absolute cell numbers were similar between LD and SD brains. Ir-fibers in LD brains were mostly in the external median eminence, along the lateral ventricle to septum (especially in and about the n. accumbens), in the septal-preoptic area, along the third ventricle, and at the n. commissure palli. There were fewer ir-fibers in SD brain. Many small dark ring-like ir-structures were found in the hyperstriatum, hippocampus, and n. taeniae. Interpreted as being ir-terminals on non-ir perikarya, these were not observed in SD males. cGnRH-II ir-perikarya were observed in only two areas regardless of reproductive status: (1) ventral to the substantia grisea centralis and caudal to the oculomotor complex, and (2) scattered in and about the lateral hypothalamus. Ir-fibers occurred in the habenular area, hyperstriatum, hippocampus, parahippocampal area, cortex piriformis, and n. taeniae. cGnRH-II ir-fibers occurred in the external median eminence but were less intensely stained than cGnRH-I ir-fibers. These fibers in SD males were similar except in the diencephalon, where scattered swellings were observed. Thus, the appearance and distribution of anti-cGnRH-I and -II ir-structures change with the sexual status of male quail, but changes in immunoreactivity to anti-cGnRH-I appear to be more widespread.

Thyrotropin releasing hormone (TRH)-immunoreactive cell groups in the rat central nervous system.

Using a paraformaldehyde-picric acid-glutaraldehyde-containing fixative and treatment of the tissue with sodium borohydride, numerous and widespread TRH-immunoreactive cell bodies were observed in the central nervous system of colchicine-treated rats, including the olfactory bulb, cortical and hippocampal areas, the caudate nucleus and other subcortical areas, many hypothalamic nuclei, the periaqueductal central gray, pontine nuclei, medulla oblongata and the dorsal horn of the spinal cord. Most of these cells could not be visualized with the same antiserum when conventional fixation methods based on formalin alone were used. The present findings suggest that TRH systems are considerably more extensive than hitherto assumed.

A monoclonal antibody to limbic system neurons.

A monoclonal antibody produced against hippocampal cell membranes labeled the surface of neurons in the rat limbic system. With a few exceptions, all nonlimbic components were unstained. This specific distribution of immunopositive neurons provides strong evidence of molecular specificity among functionally related neurons in the mammalian brain and supports the concept of a limbic system.