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At least 19 recordsLinked to original sources
PubMed1982

Brain stem innervation of the caudal neurosecretory system.

The innervation of the caudal neurosecretory system of Poecilia sphenops (black molly) was studied by use of the retrograde horseradish peroxidase (HRP) method. The structure of the caudal neurosecretory system in this species was well suited for application of HRP procedures. Acrylamide/HRP gel implants were placed in the nucleus of the caudal neurosecretory system. Two neuronal groups which contained HRP filled cells were found in the brains tem. Bilateral projections originate from the dorsal tegmentum of the midbrain and the reticular nucleus of the medulla.

Afferent Pathways↗
PubMed2001

Potential for polysialylated form of neural cell adhesion molecule-mediated neuroplasticity within the gonadotropin-releasing hormone neurosecretory system of the ewe.

The GnRH neurosecretory system undergoes marked structural and functional changes throughout life. The initial goal of this study was to examine the neuroanatomical relationship between GnRH neurons and a glycoprotein implicated in neuroplasticity, the polysialylated form of neural cell adhesion molecule (PSA-NCAM). Using dual label immunocytochemistry in conjunction with confocal microscopy, we determined that fibers, terminals, and perikarya of GnRH neurons in adult ovariectomized ewes are intimately associated with PSA-NCAM. In the preoptic area, intense PSA-NCAM immunoreactivity was evident around the periphery of GnRH cell bodies. The second goal of this study was to determine whether PSA-NCAM expression associated with GnRH neurons varies in conjunction with seasonal changes in the activity of the GnRH neurosecretory system in ovariectomized ewes treated with constant release implants of estradiol. During the breeding season when reproductive neuroendocrine activity was enhanced, the expression of PSA-NCAM immunoreactivity associated with GnRH neurons was significantly greater than that during anestrus when GnRH secretion was reduced. This difference, which occurred despite an unchanging ovarian steroid milieu, was not observed in preoptic area structures devoid of GnRH immunoreactivity, suggesting that the seasonal change is at least partially specific to the GnRH system. The close association between PSA-NCAM and GnRH neurons and the change in this relationship in conjunction with seasonal alterations in GnRH secretion provide anatomical evidence that this molecule may contribute to seasonal remodeling of the GnRH neurosecretory system of the adult.

Animals↗
PubMed1980

The caudal neurosecretory system of Poecilia sphenops (Poeciliidae).

The caudal neurosecretory system of the molly, Poecilia sphenops (Poeciliidae) was studied by light and electron microscopy. In this species the cell bodies form a focal nuclear group in the caudal spinal cord. The neurosecretory cells are in contact with glial elements, axon terminals, and the lumen of the central canal. The axons of the neurosecretory cells form a definitive tract, which leaves the spinal cord proper to penetrate a well defined neurohemal organ, the urophysis. The urophysis contains an abundance of neurosecretory granules within the neurosecretory axonal processes. This study is the first ultrastructural study of the caudal neurosecretory system in this family of fishes, which has been used as a neuroendocrine model. This species acclimates easily to the laboratory aquarium and may be most suitable for further studies on the effects of changes in external salinity on the caudal neurosecretory system.

Animals↗
PubMed1986

Vasopressin administration prevents functional recovery of the vasopressinergic neurosecretory system following neurohypophysectomy.

The rodent hypothalamic neurosecretory system normally exhibits remarkable functional and structural plasticity following injury. However, the present study describes a newly observed phenomenon in which neurohypophysectomized animals receiving chronically administered exogenous vasopressin during the post-lesion period (a treatment which insures maximal renal antidiuresis over this time frame) lose all capacity for recovery of antidiuretic function. Functional deficits are accompanied by a severe reduction in the number of neurons exhibiting immunohistochemical staining for arginine vasopressin. These data indicate that the presence of neurological stimulation signaling vasopressin release may play an important role in promoting neural regeneration of the vasopressinergic component of the neurosecretory system.

Animals↗
PubMed1996

Synthesis and release of acetylcholine by the isolated perifused trout caudal neurosecretory system.

The neurons of the caudal neurosecretory system of teleosts contain, in addition to urotensin I and urotensin II, a high concentration of acetylcholine (T. Ichikawa, 1978, Gen. Comp. Endocrinol. 35, 226-233). The isolated urophysis (and attached terminal spinal cord region) of the rainbow trout Oncorhynchus mykiss was incubated with [3H]choline (0.2 MBq/ml) for 45 min at 22 degrees in the presence of the cholinesterase inhibitor, physostigmine. Unreacted choline was removed by perifusion with fish Ringer solution. Incorporation of radioactivity into newly synthesized [3H]acetylcholine was 4.9 +/- 2.1 x 10(5) Bq/g wet tissue wt. When incubations were carried out in the presence of hemicholinium-3, an inhibitor of high-affinity choline uptake, or when physostigmine was omitted from the incubation buffer and/or when [3H]inulin was substituted for [3H]choline, the incorporation of radioactivity was greatly reduced (< 0.5 x 10(5) Bq/g). The release of [3H]acetylcholine from the preparation increased to 338 +/- 59% of basal (P < 0.05) when the concentration of K+ in the perifusion buffer was raised to 41 mM, but neither urotensin I (10(-7) M) nor urotensin II (10(-6) M) had a significant effect on release. The data indicate that the trout caudal neurosecretory system possesses a high-affinity uptake system for choline and that newly synthesized acetylcholine is released in response to a depolarizing stimulus.

Acetylcholine↗
PubMed1998

The organization of chemically characterized afferents to the perivascular neuronal groups of the hypothalamic magnocellular neurosecretory system in the rat.

The hypothalamic magnocellular neurosecretory system consists of the paraventricular nucleus and supraoptic nucleus and a number of accessory nuclei. There is evidence that each of the accessory nuclei has a preferential source of afferents. Two of the accessory nuclei, namely the nucleus circularis (NC) and the lateral hypothalamic perivascular nucleus (LHPN), are particularly interesting due to their very close relationship with the blood vessels. The NC is composed of small dense clusters of neurons in the medial anterior hypothalamus. The groups of lateral hypothalamic neurons gathering around vascular branches are collectively called the LHPN. Their close topographical relationship with the blood vessels may indicate that the latter may serve as a source of input to these nuclei. As a part of the effort to investigate this issue, the present study examined in these two nuclei the distribution pattern of terminal-like elements containing 11 transmitters/modulators. Only a few, if any, terminal-like elements of the transmitters/modulators studied could be found distributed in the NC proper, although its immediate vicinity could be densely innervated. On the contrary, the LHPN proper was often densely innervated by fibers expressing the examined markers. These terminal patterns were found to be quite different from those of the paraventricular and supraoptic nuclei. The present findings further substantiate the notion of a functional differentiation among the subnuclei of the magnocellular neurosecretory system. The significance of the relationship of these two perivascular nuclei with the blood vessels is discussed.

Animals↗
PubMed2000

The caudal neurosecretory system: control and function of a novel neuroendocrine system in fish.

The caudal neurosecretory system (CNSS) of fish was first defined over 70 years ago yet despite much investigation, a clear physiological role has yet to be elucidated. Although the CNSS structure is as yet thought to be confined to piscine species, the secreted peptides, urotensins I and II (UI and UII), have been detected in a number of vertebrate species, most recently illustrated by the isolation of UII in humans. The apparent importance of these peptides, suggested by their relative phylogenetic conservation, is further supported by the complex control mechanisms associated with their secretion. The CNSS in teleosts is known to receive extensive and diverse innervation from the higher central nervous system, with evidence for the presence of cholinergic, noradrenergic, serotonergic, and peptidergic descending inputs. Recent observations also suggest the presence of glucocorticoid receptors in the flounder CNSS, supporting previous evidence for a possible role as a pituitary-independent mechanism controlling cortisol secretion. The most convincing evidence as to a physiological role for the CNSS in fish has stemmed from the direct and indirect influence of the urotensins on osmoregulatory function. Recent advances allowing the measurement of circulating levels of UII in the flounder have supported this. In addition, there is evidence to suggest some seasonal variation in peptide levels supporting the notion that the CNSS may have an integrative role in the control of coordinated changes in the reproductive, osmoregulatory and nutritional systems of migratory euryhaline species.

Amino Acid Sequence↗
PubMed1989

A histoenzymological investigation of the caudal neurosecretory system in six species of freshwater teleosts: a comparative study.

Enzymecytochemical features of the caudal neurosecretory system of 6 species of freshwater teleosts, Gudusia chapra, Gonialosa manmina (Clupeidae, Clupeiformes), Oxygaster bacaila (Cyprinidae, Cypriniformes), Mystus bleekeri (Bagridae, Cypriniformes), Sciaena coiter (Scienidae, Perciformes), and Mastacembelus pancalus (Mastacembelidae, Mastacembeliformes) have been investigated with the help of several specific histochemical techniques. No sex-dependent variation have been observed in the enzymecytochemical characteristics of the caudal neurosecretory system of the present species. The Dahlgren cells show intense RNA activity. Caudal neurosecretion lacks carbohydrate but seems to possess small amount of lipid. Acid-phosphatase is located in the Dahlgren cells and axons. Alkaline-phosphatase has been observed in the Dahlgren cells, axons, and urophysial blood-capillaries. Acetylcholine esterase is present in the Dahlgren cells, axons, and urophysis of Mystus, Mastacembelus, and Gonialosa, but lacking in the other 3 species. It is concluded that the caudal neurosecretory system of Mystus, Mastacembelus, and Gopialosa is innervated by cholinergic neurons. Despite their different taxonomic positions, caudal neurosecretory system of all 6 species produce similar responses to various enzymecytochemical tests, except for acetylcholine esterase.

Animals↗
PubMed2002

Calcium-sensing receptors and parathyroid hormone-related protein in the caudal neurosecretory system of the flounder (Platichthys flesus).

The caudal neurosecretory system of the flounder (Platichthys flesus) has been examined by immunocytochemistry and in situ hybridization for the expression of parathyroid hormone-related protein (PTHrP) and calcium-sensing receptors (CaSR). The N-terminus nucleotide and deduced amino acid sequences of flounder PTHrP were determined and used to prepare oligonucleotide probes and homologous antiserum. The Dahlgren cells of the posterior spinal cord and their axons contained PTHrP protein which was also detected around the capillaries of the urophysis. PTHrP gene expression was abundant in the Dahlgren perikarya and axons in the spinal cord, but it was absent from nerve endings in the urophysis. Calcium-sensing receptor protein was present in the Dahlgren perikarya and axons, also with abundant gene expression, but there was neither protein nor mRNA in the urophysis. There were no apparent differences between freshwater- and seawater-adapted fish in either CaSR or PTHrP expression in the caudal neurosecretory system. These observations suggest that Dahlgren cells produce PTHrP which may be released from axons abutting capillaries in the urophysis. However, the sensing of ionic calcium appears to be confined to the perikarya of the Dahlgren cells in the spinal cord neuropil, suggesting that they are responsive to calcium in the central nervous system rather than the general circulation.

Animals↗