Search PubMed⌕ Search

Biomedical subjects

J N Hayward

Publications and source records attributed to J N Hayward.

At least 37 records · Page 2Linked to original sources
PubMed1983

Supraoptic neurons in the rat hypothalamo-neurohypophysial explant: double-labeling with Lucifer Yellow injection and immunocytochemical identification of vasopressin- and neurophysin-containing neuroendocrine cells.

By combining intracellular electrophysiology with double-labeled intracellular dye-marking and immunocytochemical identification of the same magnocellular neuroendocrine cell, we studied supraoptic neurons in the rat hypothalamo-neurohypophysial explant in vitro. This report examines neurophysiological and light microscopical features of vasopressin- and neurophysin-immunoreactive, pituitary-projecting supraoptic neurons.

Animals↗
PubMed1983

Complications of metrizamide myelography.

Adverse neurobehavioral reactions have not been emphasized as a complication of metrizamide myelography. We encountered six such reactions in approximately 250 metrizamide myelograms. All reactions followed either cervical myelography or panmyelography via lumbar puncture. We also treated a single case of tonic-clonic seizure after intracranial spill of metrizamide in a patient without a history of seizure disorder, and a case of myoclonus following a thoracic metrizamide myelogram that showed a highgrade block. Metrizamide should not be used if an intrathecal block is suspected, or if the location to be studied makes intracranial spill difficult to avoid.

Adult↗
PubMed1982

A technique combining intracellular dye-marking, immunocytochemical identification and ultrastructural analysis of physiologically identified single neurons.

A new method which produces an insoluble osmophilic polymer within Lucifer Yellow-injected neurons has allowed us to develop a technique for the ultrastructural examination of electrophysiologically characterized, immunocytochemically identified single neurons. In this initial report, we examine the light- and electron-microscopic features of neurophysin-containing, pituitary-projecting neurons in the goldfish nucleus.

Animals↗
PubMed1982

The localization of vasotocin and neurophysin neurons in the diencephalon of the pigeon, Columba livia.

Vasotocin (VT)- and neurophysin (NP)-synthesizing neurons were demonstrated by immunocytochemistry in the diencephalon of the pigeon, Columba livia. Three diencephalic regions contain VT-NP cells: (1) periventricular preoptic area and hypothalamus, including nucleus periventricularis magnocellularis (PVM); (2) lateral preoptic area and hypothalamus; and (3) dorsal diencephalon. The immunoreactive cells in each of these three regions were divided into groups based on cytology and topography. No differences were found in the location of VT and NP cell groups. The periventricular region contains three continuous cell groups (P1-P3) extending from the posteroventral preoptic area to the anterodorsal hypothalamus and PVM. The lateral region has two cell groups composed of medium- to large-sized cells associated with the quintofrontal tract (L1) or with the optic tract (L2), while a third group (L3) lies between these two cell groups. Two accessory cell groups reside in the dorsolateral hypothalamus; L4 contains scattered cells of varied size, whereas L5 has small- to medium-sized cells clumped together. The dorsal diencephalic cell groups are found in the following locations: (1) lateral and dorsal to the lateral forebrain bundle (DD1); (2) in the area ventral to the dorsomedial anterior thalamic nucleus and dorsolateral to PVM (DD2); and (3) at the dorsolateral border of nucleus rotundus (DD3). To avoid potentially inaccurate mammalian homologies, the cell group nomenclature denotes topographic position. Nevertheless, the presence of VT-NP cells in PVM and projections to the brainstem and spinal cord suggest a homology between PVM and some of the parvocellular subnuclei of the mammalian paraventricular nucleus.

Animals↗
PubMed1982

Ultrastructural immunocytochemical characterization of isotocin, vasotocin and neurophysin neurons in the magnocellular preoptic nucleus of the goldfish.

We describe the ultrastructural localization of isotocin, vasotocin and neurophysin in the magnocellular preoptic nucleus of the goldfish. With the aid of immunocytochemical techniques, we see staining both in classical neurosecretory granules and in diffuse agranular form throughout somata and processes. Signs of cellular and synaptic interactions between chemically identified neurons include axon terminals which contain vasotocin immunoreactivity and membrane specializations (puncta adhaerentia) between adjacent somata. Our investigations provide an anatomical basis for neuroendocrine and neurotransmitter-like functions of peptidergic neurons in the teleost preoptic nucleus.

Animals↗
PubMed1982

Light- and electron-microscopic characterization of electrophysiologically-identified, horseradish peroxidase-injected magnocellular neuroendocrine cells in goldfish preoptic nucleus.

We recorded intracellularly from neurons in the goldfish preoptic nucleus which were antidromically identified by electrical stimulation of the pituitary gland and marked by intracellular injection of horseradish peroxidase for subsequent localization. At the light-microscopic level, labeled neurons resembled profiles of Golgi-impregnated neurons and lay in the magnocellular portion of the preoptic nucleus. Densely labeled axons and dendrites projected to the lateral forebrain bundle, the medial forebrain bundle, fiber tracts in the preoptico-hypophysial tract, small blood vessels and capillaries, the ependymal lining of the third ventricle and toward the preoptic neurons. Occasionally, a lightly-labeled, large perikaryon lay adjacent to a large, heavily-labeled magnocellular neuron. Ultrastructural examination of these identified cells revealed dense reaction product in neuronal perikarya and processes. Heavily labeled perikarya had elaborate networks of endoplasmic reticulum, extensive Golgi apparatus, occasional somatic spines and infrequent axo-somatic contacts from unlabeled neurons. These labeled perikarya which were frequently in close somatic apposition with unlabeled profiles were sometimes adjacent to a large, lightly-labeled perikaryon. A thin glial sheath separated most labeled neurons and processes from brain capillary endothelium. Labeled dendrites had heavily labeled spines and axo-dendritic contacts from unlabeled neurons. Labeled axons abutted unlabeled-axons and -dendrites. Synaptic boutons innervating labeled structures always contained small clear synaptic vesicles and some boutons also contained large dense-core vesicles. These results demonstrate the complex connections of goldfish preoptic magnocellular neuroendocrine cells with other neurons, fiber systems, brain capillaries, ventricular ependyma and the pituitary and provide further support for non-endocrine as well as endocrine functions of magnocellular neurons.

Animals↗
PubMed1981

Ultrastructural immunocytochemical localization of enkephalin in the goldfish preoptic nucleus.

This study describes the ultrastructural localization of the opioid peptide enkephalin (ENK) in the preoptic nucleus of the goldfish. Using immunocytochemical techniques, ENK could be seen in neurosecretory granules and throughout the cytoplasm of magnocellular neurons with an agranular distribution. ENK was also associated with small clear vesicles and large dense-core vesicles within certain axon terminals in the preoptic nucleus. In this report, we discuss the cellular and synaptic relationships of ENK neurons in the preoptic nucleus of the teleost.

Animals↗
PubMed1981

Cholecystokinin in hippocampal pathways.

The distribution of cholecystokininlike (CCK-L) immunoreactive cells and fibers in the rat hippocampal formation and its afferent and efferent connections was studied using the immunoperoxidase technique. In the hippocampal formation CCK-L immunoreactive perikarya were located in the polymorphic zone of the dentate hilus, all layers of Ammon's horn, the subiculum, the presubiculum, and the entorhinal cortex. Cholecystokininlike immunoreactive fibers extended from cell bodies or were located around the cell bodies in the entorhinal cortex, subiculum and stratum pyramidale of Ammon's horn, and among the granule cells and inner molecular layer of the dentate gyrus. The immunoreactive cells in the stratum oriens may be a type of basket cell, since processes from these cells extend into stratum pyramidale and collections of CCK-L immunoreactive fibers are seen around cell bodies in stratum pyramidale. Cholecystokininlike immunoreactive fibers were also observed in the alveus, ventral and lateral fimbria, and ventrolateral lateral septal nucleus. Some of these immunoreactive fibers, therefore, being to either an efferent or afferent hippocampal pathway(s) originating from CCK-L immunoreactive pyramidal cells in the hippocampal formation and/or from the hippocampal subcortical nuclei, the supramammillary nucleus, and the dorsomedial hypothalamic nucleus which contain CCK-L immunoreactive perikarya. The distribution of these immunoreactive fibers in the fimbria and lateral septal nucleus is most consistent with an anteriorly directed efferent hippocampal pathway.

Afferent Pathways↗
PubMed1981

Dye-marked paraventricular neuroendocrine cells in vivo in cat hypothalamus.

In antidromically identified neurons in the cat hypothalamus we recorded and injected fluorescent dye-markers (Lucifer Yellow, LY; Procion Yellow, PY) intracellularly. The dye-filled neurons lay in the rostral portion of the magnocellular paraventricular nucleus of the hypothalamus. We observed two morphological cell types of similar size based on the intracellular injections of LY or PY: a bipolar cell type with fusiform perikaryon and a multipolar cell type with a polygonal perikaryon. These morphological cell types correspond to previous descriptions of immunocytochemically identified vasopressinergic and oxytocinergic magnocellular neurons in mammals. This study demonstrates the feasibility of in vivo intracellular dye-marking and electrophysiological recordings from mammalian hypothalamic neurons. We have here a basis for correlating morphological characteristics with the physiological traits of single magnocellular neuroendocrine cells.

Action Potentials↗
PubMed1981

Vasopressin release by nicotine in the cat.

Our goal in this study was to examine where nicotine acted on the neurohypophysial release of arginine vasopressin (AVP). In the chamber-isolated, unanesthetized cat, an IV infusion of nicotine (25--50 micrograms/kg/min for 10 min) produced a 54-fold rise in plasma AVP (65 +/- 12.5 microU/ml) and a behavioral sequence of restlessness, ear twitching, salivation, chewing and retching. Chloralose anesthesia and acute surgical preparation increased plasma AVP (9.4 +/- 3.8 microU/ml) 4-times the control level in the unanesthetized state (2.4 +/- 0.1 microU/ml). In the anesthetized cat, an IV infusion of nicotine produced a 140-fold rise in plasma AVP (802.7 +/- 289.0 microU/ml) and a biphasic response in mean arterial blood pressure (MABP) which rose to 32% above control in the first 5 min and fell to 25% below control during the last 5 min. Bilateral surgical section of the carotid sinus and vagus nerves increased plasma AVP (47.6 +/- 25.8 microU/ml) to 5-times the control level in the anesthetized state (9.4 +/- 3.8 microU/ml). In the anesthetized, baroreceptor-denervated cat, an IV infusion of nicotine produced a 3-fold rise in plasma AVP (141.5 +/- 31.3 microU/ml) and a biphasic MABP response. Hypophysectomy abolished the nicotine-induced rise in AVP but did not modify the biphasic MABP response. These data suggest that in the cat nicotine releases AVP from the neurohypophysis by multiple sites of action within the receptive fields of te carotid sinus and vagus nerves and at unknown loci within the central nervous system.

Animals↗
PubMed1981

Osmotic regulation of vasopressin in the cat.

This study examines the effects of blood osmolality on the release of arginine vasopressin (AVP) in the cat. Prior to the beginning of the experiments, the chamber-isolated, unanesthetized cat, allowed water ad libitum had a constant plasma osmolality averaging 320 +/- 2 (SE) mosmol/kg and a constant plasma AVP averaging 3.4 +/- 0.7 microU/ml. Water loading decreased plasma osmolality to 312 +/- 2 mosmol/kg and lowered plasma AVP to 1.3 +/- 0.2 microU/ml. As dehydration occurred during fluid restriction, the plasma osmolality increased and plasma AVP rose to 8 times the base line after 2 days. The rise in plasma AVP correlated linearly with the rise in plasma osmolality (r = 0.81; P less than 0.01). The cat's osmotic-vasopressin relationships are unique among mammals, revealing an elevated osmotic "set point" (threshold) and with regression analysis an increased "gain" or "'sensitivity" (increased slope of the regression line). We speculate that these unusual osmotic-AVP relationships may be related to some specialized features of the cat, such as hypothalamic anatomy or cerebral arterial blood supply.

Animals↗
PubMed1980

Functional and morphological studies of peptide-containing neuroendocrine cells in goldfish hypothalamus.

We report the development of a double-label method which combines intracellular recording, dye-marking, and immunocytochemistry for the study of functional and morphological aspects of peptide-containing neurons in the magnocellular preoptic nucleus of the goldfish hypothalamus. Using multiple techniques, we distinguish three types of peptide-containing neurons: enkephalin (27%), isotocin (49%), and vasotocin (24%). Drawings of serial sections containing the dye-injected cells were the basis for subsequent reconstruction. These peptide-containing cells measure 14-56 micrometer in somata diameter, are unipolar, bipolar, or multipolar in somata shape and lie 6-244 micrometer from the ependymal lining of the preoptic recess of the third ventricle. Their electrophysiological properties match those of other mammalian and fish magnocellular neuroendocrine cells. This report confirms the one neuron, one hormone (peptide) hypothesis, supports synaptic over electrotonic coupling between peptidergic and adjacent hypothalamic neurons, and suggests that chemical and functional classification of single electrophysiologically and neuroanatomically studied central neurons is feasible technologically.

Animals↗
PubMed1979

Isotocinergic neurons in the goldfish hypothalamus: physiological and morphological studies on chemically identified cells.

Isotocinergic (IT) neurons show physiological and morphological characteristcs that are similar to those of the other preoptic neuroendocrine cells in the goldfish. Preoptic IT cells show resting membrane potentials of 20-55 mV, action potentials of up to 100 mV, and physiological evidence of axonal branching. Dye-marked IT cells measure 14-56 micrometers, their dendrites projecting to the ependyma and into the hypothalamic neuropil, their multiple beaded axons projecting to the pituitary. Indirect immunofluorescence identifies these dye-marked cells as IT. By combining electrophysiological, dye-marking and immunocytochemical techniques we can now, for the first time, study single, antidromically-identified peptidergic neurons of a specific type in vertebrate and invertebrate species.

Animals↗
PubMed1979

Immunocytochemical identification of enkephalinergic neurons in the hypothalamic magnocellular preoptic nucleus of the goldfish, Carassius auratus.

Our immunocytochemical investigation of the magnocellular neuroendocrine system in the goldfish hypothalamus reveals enkephalin (ENK)-containing neurons interspersed among the vasotocin (VT)- and isotocin (IT)-containing neurons of the preoptic nucleus. The perikarya of the ENK, VT, and IT neurons do not show distinct morphological differences at the level of light microscopy and are not located preferentially within the nucleus. Separate ENK, VT and IT fibers course laterally and ventrally through the hypothalamus as they descend toward the pituitary gland. All three fiber types form terminals around blood vessels in the neurohypophysis.

Animals↗
PubMed1979

Immunocytochemical identification of vasopressinergic and oxytocinergic neurons in the hypothalamus of the cat.

Our immunocytochemical investigation of the magnocellular neuroendocrine cells in the cat hypothalamus reveals a mixture of vasopressin (VP)- and oxytocin (OT)-containing neurons in the supraoptic (NSO), the paraventricular (NPV) and in five accessory nuclei (NAC). We describe the lateral hypothalamic nucleus (NLH), a new accessory nucleus, lying at the junction of the internal capsule and pallidum, and possibly involved in drinking behavior. Previously characterized incompletely in mammals, the four other accessory nuclei consist of the circularis (NC), anterior fornical (NAF), posterior fornical (NPF) and retrochiasmatic (NRC). The two peptidergic cell types, VP and OT, are equally mixed in the NPV and the NAC, but in the NSO VP neurons predominate. The perikarya of these VP and OT neurons do not show distinct morphological differences at the level of light microscopy. The organization of magnocellular neuroscretory neurons in the cat hypothalamus closely resembles that described in other mammals with the exception of the unique presence of the lateral hypothalamic accessory nucleus.

Animals↗
PubMed1979

Intracellular dye-marked enkephalin neurons in the magnocellular preoptic nucleus of the goldfish hypothalamus.

A method that combines intracellular recording, dye marking, and immunocytochemistry makes the study of functional and morphological aspects of enkephalin neurons in the magnocellular preoptic nucleus of the goldfish hypothalamus feasible. By use of multiple techniques, enkephalin neurons can be distinguished from other brain cells and can be reconstructed from drawings of serial sections containing the dye-injected opioid cells. These enkephalin cells and their processes measure 14-42 micron in somata diameter and are unipolar, bipolar, or multipolar. Their electrophysiological properties match those of other mammalian and fish magnocellular endocrine cells. This report confirms the one neuron-one hormone (peptide) hypothesis, supports synaptic over electronic coupling between enkephalin and adjacent hypothalamic neurons, and suggests that chemical and functional classification of single electrophysiologically and neuroanatomically studied central neurons can be achieved.

Action Potentials↗