Vasopressin autoreceptors and nitric oxide-dependent glutamate release are required for somatodendritic vasopressin release from rat magnocellular neuroendocrine cells responding to osmotic stimuli.

Magnocellular neuroendocrine cells of the supraoptic nucleus (SON) release vasopressin (VP) systemically and locally during osmotic challenge. Although both central VP and nitric oxide (NO) release appear to reduce osmotically stimulated systemic VP release, it is unknown whether they interact locally in the SON to enhance somatodendritic release of VP, a phenomenon believed to regulate systemic VP release. In this study, we examined the contribution of VP receptor subtypes and NO to local VP release from the rat SON elicited by systemic injection of 3.

A novel role for endogenous pituitary adenylate cyclase activating polypeptide in the magnocellular neuroendocrine system.

Central release of vasopressin (VP) by the magnocellular neuroendocrine cells (MNCs) responsible for systemic VP release is believed to be important in modulating the activity of these neurons during dehydration. Central VP release from MNC somata and dendrites is stimulated by both dehydration and pituitary adenylate cyclase activating polypeptide (PACAP). Although PACAP is expressed in MNCs, its potential role in the magnocellular response to dehydration is unexplored.

Glutamate release in parabrachial nucleus and baroreflex alterations after vagal afferent activation.

The parabrachial nucleus (PBN) is a regulatory nucleus that relays visceral information from the brain stem to the cortex. Immunohistochemical studies have shown that the levels of various neuropeptides in the PBN were changed after visceral afferent activation. Because the major transmitter relaying visceral information through the PBN is glutamate, the present study asked if glutamate release into the PBN also was changed after vagal afferent activation in anesthetized male rats.

Secretion and serotonin release in the isolated rat lacrimal gland: the effects of substance P and calcitonin gene-related peptide.

A close anatomical relationship between nerves containing substance P and calcitonin gene-related peptide (CGRP) and mast cells containing serotonin has been demonstrated in the rat lacrimal gland. This study investigates the potential for peptidergic regulation of lacrimal mast cells by examining the actions of substance P, CGRP and serotonin on protein and peroxidase secretion from isolated lacrimal segments and on substance P and CGRP to release serotonin from the lacrimal mast cells. Substance P, CGRP and serotonin evoked marked increases in total protein and peroxidase from the lacrimal.

Dopaminergic transmission between identified neurons from the mollusk, Lymnaea stagnalis.

1. Dopaminergic transmission was investigated in the central nervous system (CNS) of the freshwater snail, Lymnaea stagnalis. 2.

Osmotic responsiveness and cross talk involving oxytocin, but not vasopressin or amino acids, between the supraoptic nuclei in virgin and lactating rats.

Lactation is associated with complex changes of the hypothalamo-neurohypophysial system, and oxytocin released within the hypothalamic supraoptic (SON) and paraventricular nuclei may serve as a signal of communication between the magnocellular nuclei in lactating rats. In the first study, the intranuclear and peripheral release patterns of oxytocin and vasopressin in response to intraperitoneal hypertonic saline were studied in virgin and lactating rats to determine if the reduced osmoresponsiveness of the oxytocinergic and vasopressinergic systems during lactation is reflected by reduced release not only into blood, but also within the SON. Simultaneous microdialysis was performed within the SON and the jugular vein before and up to 6 hr after peripheral osmotic stimulation (3.

Microdialysis with high NaCl causes central release of amino acids and dopamine.

Recent studies have shown that the neuropeptides arginine-8-vasopressin (AVP) and oxytocin (OXT) are released within the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus in response to microdialysis of these nuclei with high-NaCl perfusion media. These results suggest an inherent osmosensitivity of SON and PVN neurons. To investigate whether the observed release of AVP/OXT is a unique phenomenon to these neuropeptides, several brain regions were examined for the release of amino acids or dopamine in response to high- or low-NaCl stimulation.

Nitric oxide actions in paraventricular nucleus: cardiovascular and neurochemical implications.

We have examined potential functions of nitric oxide (NO) within the paraventricular nucleus (PVN) in urethan-anesthetized male Sprague-Dawley rats. Initial experiments demonstrated microinjection of 50 pmol of the NO donor, sodium nitroprusside (SNP), directly into the PVN resulted in significant decreases in mean blood pressure (BP) (-3,312 +/- 1,189 mmHg/s over 300-s response time; P < 0.05).

Identification, characterisation and in vitro reconstruction of an interneuronal network of the snail Helisoma trivolvis.

1. We describe three interneurones and their follower cells in the central ganglionic ring of Helisoma trivolvis. 2.

A method for continuous blood sampling during cold water immersion.

A technique, consisting of a pre-calibrated, catheter-peristaltic pump combination, for continuous blood sampling was tested using six volunteers during a 20 min immersion in cold water at 14.7 +/- 0.9 degrees C.

Role for the submandibular gland in modulating pulmonary inflammation following induction of systemic anaphylaxis.

Previous studies have shown that bilateral decentralization of the superior cervical ganglia (SCG; decentralization) attenuates allergen-induced pulmonary inflammatory responses in male rats sensitized to the nematode Nippostrongylus brasiliensis. The present report examines the neuronal and glandular mechanisms mediating the protection against pulmonary inflammation afforded by decentralization. Tissues and organs innervated by the SCG are responsible for this protection since, in a manner similar to decentralization, bilateral removal of the SCG (ganglionectomy) reduced anaphylaxis-induced accumulation of inflammatory cells in bronchoalveolar lavage fluid.

Evidence for the presence, synthesis, immunoreactivity, and uptake of GABA in the nervous system of the snail Helisoma trivolvis.

In the present study several techniques were employed to test the hypothesis that gamma-aminobutyric acid (GABA) is a neurotransmitter in the central nervous system (CNS) of the pond snail Helisoma trivolvis (Mollusca, Pulmonata). First, by using chromatographic techniques, the presence of GABA and its differential distribution among the ganglia constituting the CNS was demonstrated. Second, de novo synthesis of 3H-GABA from 3H-glutamate was shown by the CNS.

Kainate receptors coupled to the evoked release of [3H]-gamma-aminobutyric acid from striatal neurons in primary culture: potentiation by lithium ions.

The pharmacological properties and modulation by lithium of the kainate (KA) receptor system coupled to the evoked release of [3H]-gamma-aminobutyric acid [( 3H]GABA) from purified populations of striatal neurons in primary culture were examined. KA evoked a dose-dependent (EC50, 100 microM) and saturable increase in [3H]GABA release from striatal neurons that was unaffected by the removal of extracellular calcium and resistant to the actions of tetrodotoxin. The release of [3H]GABA evoked by 100 microM KA was attenuated in a dose-dependent manner by the following excitatory amino acid antagonists (IC50):6-cyano-2, 3-dihydroxy-7-nitroquinoxaline (2 microM),2,3-dihydroxy-6,7-dinitroquinoxaline (2 microM), kynurenate (0.

Kainate evokes the release of endogenous glycine from striatal neurons in primary culture.

The actions of 56 mM KCl and excitatory amino acid (EAA) agonists on the release of endogenous glycine (Gly) from striatal neurons in primary culture was examined. During a 3 min period, 2 x 10(6) striatal neurons released 743 +/- 51 pmol of Gly. In the presence of 56 mM KCl, an additional 492 +/- 52 pmol of Gly (+66%) were released, 75% of which was dependent upon the presence of extracellular calcium.

Plasma catecholamines in conscious rabbits after central administration of vasopressin.

Arterial levels of epinephrine (E) were significantly raised for all times sampled, after intracerebroventricular (i.c.v.

Depletion of central catecholamines reduces pressor responses to arginine vasopressin.

Previous reports that central administration of arginine vasopressin (AVP) increases turnover of brain catecholamines raise the possibility that the pressor responses which follow central administration of AVP may be mediated, in part, by central catecholamines. To test this hypothesis, rats were given intraventricular injections of vehicle, or of the neurotoxin, 6-hydroxydopamine, which resulted in significant depletions of hypothalamic and medulla oblongata noradrenalin and hypothalamic dopamine, but not of medullary dopamine or of hypothalamic and medullary 5-hydroxytryptamine. Following a one week recovery, these conscious rats, fitted with indwelling arterial catheters, were given intraventricular injections of AVP; the increases in arterial pressure and heart rate were significantly reduced in the catecholamine-depleted animals.

Mugineic acid: non-selective enhancement of excitatory amino acid actions on rat central neurones.

The effects of mugineic acid upon excitations induced by quisqualic acid (quis), N-methyl-D-aspartic acid (NMDA) and kainic acid (kain) on rat central neurones were examined in vivo through microiontophoretic drug administration in anaesthetized rats. Mugineic acid usually caused a non-selective enhancement of drug-induced excitations, occasionally producing direct excitation itself or increasing the rate of spontaneous discharge. Mugineic acid-induced effects were not blocked by the NMDA selective antagonist, 2-amino-5-phosphonovaleric acid (AP5).

Transient depletion of serotonin in the nervous system of Helisoma.

The present study shows that the drug 5,7-dihydroxytryptamine (5,7-diHT) can be used reliably to deplete the neurotransmitter serotonin (5-HT) from the nervous system of the snail Helisoma. The depletion is more effective in axonal and synaptic regions (85-90%) than in the somata (55%), is reasonably specific for serotonin (dopamine is affected to a much lesser extent), and is transient, with normal levels of neurotransmitter being restored by 2 months. A physiological correlate of 5-HT depletion has been shown in that an EPSP elicited by a cerebral serotonergic neuron (C1) onto a buccal motoneuron (B19) is much smaller during depletion and also recovers with time as 5-HT regains normal concentration.

Alcohol dependence and withdrawal in the rat. An effective means of induction and assessment.

Numerous problems have been associated with previous attempts to develop a suitable method for the induction and assessment of alcohol dependence and withdrawal syndrome in the rat. Using our modification of a common inhalation method for the long-term administration of ethanol, these problems can be eliminated. Adult male rats (Long Evans and Brattleboro) were exposed to ethanol vapor concentrations of 7 to 35 mg/liter of air, which cause rapid development of tolerance and physical dependence.

The effects of intrathecal administration of arginine-vasopressin and substance P on blood pressure and adrenal secretion of epinephrine in rats.

The effects of intrathecally administered arginine-vasopressin (AVP) and substance P (SP) on adrenal medullary secretion of epinephrine were examined in anesthetized Sprague-Dawley rats. Plasma epinephrine levels were measured in blood samples taken directly from the adrenal vein using a novel micropuncture technique. The blood samples (20-30 microliter in volume) were taken before, and 2 min, 15 min and 30 min after intrathecal injections of AVP, SP or vehicle only.

Determination of the endogenous and evoked release of catecholamines from the hypothalamus and caudate nucleus of the conscious and unrestrained rat.

The action of catecholamines within the CNS is important for the expression of numerous vegetative and behavioral functions. To understand the role these amines play, it is necessary to measure changes in the levels of these transmitter substances by utilizing new developments and methodology in the behaving animal. Utilizing new developments in methodology, it is possible to measure the release of amines into perfusates obtained from specific sites in the brain of the rat under basal and evoked conditions without prior purification or concentration.

An investigation of the age-related deficits in the febrile response of the rabbit.

The febrile response of the New Zealand White rabbit in animals less than 1 yr old was compared with that in 3-yr-old animals. A reduced febrile response to both endotoxin and live bacteria injected intravenously was observed in the older group of animals. Peripheral vasoconstriction was observed, suggesting the drive to increase body temperature remained.

Synthesis and assay for activity of a proposed anorexogenic agent, L-pyroglutamyl-L-histidyl-glycine.

L-Pyroglutamyl-L-histidyl-glycine has been reported to be an anorexogenic agent in female mice. In this report the synthesis of this tripeptide is described. The synthetic material was injected into female and male mice and into male rats.

Synthesis of a series of residue 1 (pyroglutamic acid) analogs of thyrotrophin releasing hormone.

This report describes the synthesis of 23 analogs of thyrotrophin releasing hormone, L-pyroglutamic acid-L-histidyl-L-prolineamide, where only the pyroglutamic acid moiety is modified. Twelve of the analogs contain different heterocyclic rings or are derivatized pyrrolidone rings. The syntheses of these pyroglutamic acid analogs are also described.