PubMed Health⌕ Search

Biomedical subjects

J Ciriello

Publications and source records attributed to J Ciriello.

At least 109 records · Page 6Linked to original sources
PubMed1983

Central projections of afferent renal fibers in the rat: an anterograde transport study of horseradish peroxidase.

The projections of afferent renal fibers (ARN) to dorsal root ganglia and into the spinal cord of the rat were studied using the anterograde transport of horseradish peroxidase (HRP). Crystalline HRP was applied to the proximal cut ends of renal nerves or injected as a concentrated solution into the kidney, on either the right or left side. After a survival time of 40-120 h, sections of thoraco-lumbar dorsal root ganglia (DRG) and spinal cord were cut and processed according to the tetramethyl benzidine method. HRP applied either to the ARN or to the kidney on the left labeled neurons in the DRG from T8 to L2. On the other hand, HRP application on the right side resulted in labeling of neurons in DRG T6 to T13. No labeled neurons were found in the contralateral DRG. Labeled neurons in the DRG were of the small (11-20 micron) and medium (30-42 micron) size and were distributed in all portions of the DRG. In the spinal cord the greatest concentration of labeled ARN from the left were found in segments T10-L1, whereas projections from the right ARN were concentrated primarily in segments T7-T10. Labeled fibers entered along the medial aspect of the ipsilateral dorsal horn and projected both rostrally and caudally in the medial portion of Lissauer's tract, sending some collaterals into lamina I. The majority of labeled fibers coursed ventrally along the medial aspect of the dorsal horn towards the midline where they terminated in the region of the dorsal gray commissure, just dorsal to the central canal. Additionally, labeled fibers from the medial projection passed into laminae III-V. No labeled fibers or terminals were observed in the contralateral spinal cord. These data show that ARN enter the spinal cord through several DRG and provide the first anatomical demonstration of central sites of termination of ARN. These spinal sites of projection of sensory information from the kidney are likely to be central sites of integration of reno-renal and visceral reflexes.

Animals↗
PubMed1982

Medullary origin of vagal preganglionic axons to the heart of the cat.

It is apparent from the literature that a controversy exists concerning the site of origin of cardiac vagal preganglionic axons. Physiological studies have suggested that the location of these neurons may be different in different species and there has been disagreement between physiological and anatomical findings in the same species. We now present anatomical and neurophysiological studies suggesting that in the cat cardiac vagal preganglionic neurons are located in two medullary regions: the areas of the dorsal motor nucleus of the vagus (DMV) and of the nucleus ambiguus (AMB). This suggestion is based on the following observations. Firstly, after application of horseradish peroxidase to the right cardiac branches of the vagus nerve, labeled neurons were found primarily in the regions of te DMV and AMB. Additional scattered neurons were found in the reticular formation between these two nuclei. Secondly, following injections of tritiated amino acids into either the DMV or AMB, labeled vagal fibers were found in the atrial myocardium. Finally, electrical stimulation of the right cardiac branches of the vagus nerve antidromically activated DMV or AMB, labeled vagal fibers were found in the atrial myocardium. Finally, neurons in the DMV and AMB regions with latencies corresponding to conduction velocities of B-fibers. In addition, these neurons were orthodromically excited by electrical stimulation of the carotid sinus and aortic depressor nerves.

Animals↗
PubMed1981

Glossopharyngeal and vagal afferent projections to the brain stem of the cat: a horseradish peroxidase study.

Brain stem projections of the glossopharyngeal and vagus nerves in the cat were studied using the anterograde transport of horseradish peroxidase (HRP). Crystalline HRP was applied to the proximal cut ends of the nerves for a period of 4-10.5 h, and after a survival time of 24-120 h, transverse and horizontal sections of the brain stem were processed according to the tetramethylbenzidine method. Labeled fibers from both nerves were found to project bilaterally to the solitary complex, and ipsilaterally to the ventral region of the external cuneate nucleus and to the medial region of the nucleus praepositus hypoglossi, just dorsolateral to the medial longitudinal fasciculus. Within the solitary complex terminal labeling was found in the parvocellular, ventrolateral, lateral, medial and commissural solitary nuclei. Exclusive glossopharyngeal nerve projections were found ipsilaterally in the rostral dorsal motor nucleus of the vagus, the ventrolateral portion of the medial cuneate nucleus, the dorsal part of the nuclei caudalis and interpolaris of the trigeminal complex, the nuclei insulae cuneati lateralis, and the dorsolateral aspect of the nucleus medullae oblongata centralis. Finally, in the area postrema a bilateral projection of vagal and an ipsilateral projection of glossopharyngeal fibers were found. These findings demonstrate that the glossopharyngeal nerve has more widely distributed brain stem projections that the vagus nerve and provide essential information on projection sites of visceral and taste inputs to the central nervous system.

Afferent Pathways↗
PubMed1981

Projections from buffer nerves to the nucleus of the solitary tract: an anatomical and electrophysiological study in the cat.

The projections of aorta depressor (ADN) and carotid sinus (CSN) afferent fibers to the region of the nucleus of the solitary tract were studied in the cat with the anterograde transport of horseradish peroxidase (HRP) technique and by recording single unit activity during electrical stimulation of these nerves. In the first series of experiments, after application of crystalline HRP to the proximal cut end of either buffer nerve and a postoperative survival period of 24-120 h, brain stem sections were processed according to the tetramethyl benzidine method. ADN and CSN labeling were found bilaterally, with a predominant ipsilateral labeling, in the medial (Sm), lateral (Slt), commissural (Com) and dorsomedial aspect of the parvocellular solitary nuclei. Additional CSN labeling was found in the ventrolateral and intermediate (Int) solitary nuclei, in the reticular formation ventrolateral to the solitary complex and along the dorsal border of the dorsal motor nucleus of the vagus. In the second series of experiments these areas receiving primary afferent fibers were explored for single units responding to stimulation for the buffer nerves in chloralosed cats, paralyzed and artificially ventilated. Of 177 responsive units, 80 responded only to stimulation of the CSN, 44 only to the ADN and 53 to both nerves. Responsive units were found throughout the rostrocaudal extent of the solitary complex and areas adjacent to the solitary complex. However, most of the units were found in 3 regions: the Sm, Slt and adjacent areas. Units in the Slt and Com were found to respond to only one input, either the CSN or the ADN alone. On the other hand, units in the Int responded only to both buffer nerves and not selectively to one nerve. These results demonstrate that the CSN has a wider distribution in the solitary complex than the ADN and that second order neurons in the solitary complex receive inputs from either one or both buffer nerves, suggesting a degree of separation of central pathways carrying cardiovascular afferent information.

Afferent Pathways↗
PubMed1981

Altered concentration of catecholamines in the hypothalamus of the rat after renal denervation.

Concentrations of noradrenaline, adrenaline, and dopamine were measured using a sensitive radioenzymatic assay in hypothalamic nuclei of rats 4 days after bilateral renal denervation. After renal denervation, catecholamine levels in several hypothalamic nuclei were found to be different from those of sham-operated animals. Noradrenaline was found to be increased in the supraoptic nucleus, adrenaline was increased in the paraventricular nucleus and lateral hypothalamic area, and dopamine was decreased in the supraoptic nucleus, medial preoptic nucleus and lateral hypothalamic area. These data suggest that afferent renal fibers influence the metabolism of hypothalamic catecholamines and that neural information originating in the kidney and transmitted to the hypothalamus is probably involved in physiological responses related to cardiovascular adjustments and body fluid balance.

Animals↗
PubMed1981

Noradrenergic mechanisms in brain and peripheral organs after aortic nerve transection.

Noradrenergic mechanisms were studied in the hypothalamus, midbrain, medulla, kidney, duodenum, and skeletal muscle of Wistar rats at 3 or 13 days after either bilateral transection of the aortic depressor nerve (ADN) or a sham operation. The rate of decline of tissue norepinephrine (NE) concentration after inhibition of tyrosine hydroxylase with alpha-methyltyrosine was used as an index of NE turnover. Three days after ADN transection, arterial pressure and heart rate were elevated significantly, and NE turnover was increased in all three brain areas, kidney, and skeletal muscle but not in duodenum. The largest change occurred in skeletal muscle, where the time required for tissue NE concentration to decline to 50% of control decreased from 9.0 to 2.5 h. In rats 13 days after ADN transection, arterial pressure was significantly higher than in sham-operated controls, but heart rate was similar to control values. NE turnover was slightly increased in hypothalamus but was not significantly different in muscle and kidney when compared to sham-operated controls. These results suggest that 3 days after ADN transection in the rat, arterial pressure is elevated as a result of increased activity of noradrenergic neurons in the hypothalamus and brain stem, which is translated into increased sympathetic nerve activity to peripheral organs, particularly skeletal muscle. The normal turnover of NE in peripheral organs 13 days after ADN transection suggests that mechanisms other than increased sympathetic activity are responsible for maintaining the elevated arterial pressure.

Animals↗
PubMed1980

Hypothalamic projections of renal afferent nerves in the cat.

In 10 cats anaesthetized with chloralose the electrical activity of spontaneously active hypothalamic units was recorded for changes in discharge rate during electrical stimulation of renal afferent nerves. The discharge rate of 141 single units was altered by stimulation of either the ipsilateral or contralateral renal nerves. Most of the responsive units were located in the regions of lateral preoptic nucleus, lateral hypothalamus, and paraventricular nucleus. These results demonstrate that renal afferent nerves provide information to hypothalamic structures known to be involved in the regulation of arterial pressure and fluid balance.

Afferent Pathways↗
PubMed1980

Distribution of vagal cardioinhibitory neurons in the medulla of the cat.

Experiments were done in cats anesthetized with chloralose, paralyzed and artificially ventilated cats to obtain electrophysiological evidence on the medullary site of origin of vagal cardioinhibitory fibers. The regions of the nucleus ambiguus (AMB), dorsal motor nucleus of the vagus (DMV), nucleus tractus solitarius (NTS), and external cuneate nucleus (ECN) were systematically explored for units responding both to antidromic stimulation of the cardiac branches of the vagus (CBV) and to orthodromic stimulation of the carotid sinus and aortic depressor nerves. Eighty-six single units conforming to these criteria were found in the medulla: 30 in the AMB, 26 in the DMV, 12 in the NTS, 8 in the NTS-DMV border region, and 10 in the ECN. Antidromically evoked spikes had durations of 0.5--2.5 ms and followed stimulation frequencies of 20--500 Hz. The axons of these units conducted at velocities of 3.3--20.8 m/s. The specificity of activation of medullary units by cardioinhibitory fibers was tested in 11 units, which were found to respond consistently with an antidromic spike to stimulation of CBV but not to stimulation of the thoracic vagus. In eight spinal animals low threshold (less than 15 microA) sites eliciting vagal bradycardia were found in the same medullary nuclei where cardioinhibitory units had been located. These results indicate that vagal cardioinhibitory axons, originate in at least three medullary nuclei, the AMB, DMV, and NTS. Unit activity from the ECN may have been recorded from carioinhibitory fibers because of the short duration of the spike potentials.

Animals↗
PubMed1980

Projections to the hypothalamus from buffer nerves and nucleus tractus solitarius in the cat.

In 18 cats anesthetized with chloralose, electrical activity of spontaneously active hypothalamic units was monitored for changes in firing frequency during electrical stimulation of carotid sinus (CSN) and aortic depressor (ADN) nerves and the nucleus tractus solitarius (NTS). Stimulation of the CSN altered the activity of 55% (381/691) of the tested. These responsive units were widely distributed in the ipsi- and contralateral hypothalamus. Of the units tested during stimulation of the ADN only 6% (17/274) changed their firing frequency. Responsive units were located only on the ipsilateral side and primarily in the paraventricular and supraoptic nuclei, Electrical stimulation of the NTS altered the firing frequency of all 84 hypothalamic units previously identified by stimulation of the CSN. NTS stimulation elicited responses that had a significantly shorter latency and followed significantly higher frequencies of stimulation when compared to stimulation of the CSN. These results demonstrate that the two buffer nerves have distinctly different central projections to the hypothalamus and suggest different functional roles for the ADN and CSN in homeostatic regulatory mechanisms mediated by the hypothalamus.

Animals↗
PubMed1980

Role of paraventricular and supraoptic nuclei in central cardiovascular regulation in the cat.

To investigate the role of the paraventricular (PAH) and supraoptic (SON) nuclei in regulation of the cardiovascular system experiments were done in 26 cats anesthetized with alpha-chloralose, paralyzed, and artificially ventilated. Electrical stimulation of histologically verified sites in the region of the PAH and SON elicited increases in arterial pressure in bilaterally vagotomized animals and increases in heart rate both in spinal (C2) animals and in animals bilaterally vagotomized, In addition, stimulation of either the PAH or SON inhibited the reflex vagal bradycardia elicited by stimulation of the carotid sinus nerve (CSN) and bilateral lesions of these areas increased the magnitude of the response. On the other hand, stimulation and lesions of these hypothalamic regions did not alter the magnitude of the cardiovascular responses to stimulation of the aortic depressor nerve. These results demonstrate that stimulation of the PAH and SON elicit cardiovascular responses due to reciprocal changes in activity of the parasympathetic and sympathetic nervous systems and that these structures maintain a tonic inhibitory influence on the heart rate component of the CSN reflex.

Animals↗
PubMed1979

Separate medullary pathways mediatiating reflex vagal bradycardia to stimulation of buffer nerves in the cat.

In this investigation of medullary pathways mediating reflex vagal bradycardia to stimulation of buffer nerves, four series of experiments were done in 37 cats anesthetized with chloralose, paralyzed and artificially ventilated. In the first series using animals in which the contralateral vagus was sectioned and the spinal cord was transected at C2, simultaneous stimulation of the aortic depressor (ADN) and carotid sinus (CSN) nerves elicited a bradycardia of magnitude not significantly different from the algebraic sum of the responses elicited by stimulation of the two buffer nerves separately, suggesting the existence of two separate central pathways mediating vagal bradycardia. In the second series, in spinal unilaterally vagotomized animals, lesions of the nucleus ambiguus (AMB) selectively attenuated the ADN reflex vagal bradycardia but not the CSN response; on the other hand, lesions of the external cuneate nucleus (ECN) attenuated the reflex vagal bradycardia elicited by stimulation of the CSN, but did not alter the ADN response. In the third series of experiments, 153 spontaneously firing single units in the region of the AMB and 98 in the region of the ECN were tested for responses to ADN and CSN stimulation. In the AMB 42% of the responsive units were excited only by stimulation of the ADN, 25% were activated only by stimulation of the CSN and 33% were activated by stimulation of both buffer nerves. Of the single units in the ECN region 85% were excited only by stimulation of the CSN, 15% during stimulation of both the CSN and ADN and none responded to stimulation of only the ADN. In the final series, electrical stimulation of the ECN evoked antidromic compound action potentials in the CSN but not in the ADN. Electrical stimulation of the AMB did not evoke antidromic activity in either the CSN or ADN. These studies provide evidence for the existence of two separate medullary pathways mediating the vagal reflex bradycardia to stimulation of the ADN and CSN.

Animals↗
PubMed1978

Vagal bradycardia elicited by stimulation of the external cuneate nucleus in the cat.

The role of the external cuneate nucleus (ECN) in the control of heart rate was systematically investigated in 26 chloralosed and 2 decerebrated, paralyzed, and artifically ventilated cats. Electrical stimulation of histologically verified sites in the ventral ECN and dorsal spinal trigeminal tract elicited a marked decrease in heart rate, with threshold currents of 5-25 muA and an optimal frequency of 20 Hz when using a 0.2 ms pulse; this response was shown to be due to vagal excitation. In seven experiments intravenous pentobarbital sodium decreased the magnitude of the bradycardia elicited by stimulation of the ECN, of the nucleus ambiguus (AMB), and of the cervical vagus significantly less than the response from the nucleus of the tractus solitarius. In eight additional experiments in cats with lesions of the AMB made 11-27 days earlier stimulation of the ECN elicited a bradycardia of the same magnitude as that observed in intact animals, although the bradycardia elicited by stimulation of the ipsilateral cervical vagus was significantly reduced by the lesion. Similarly, lesions of the ECN in four cats significantly attenuated the bradycardia elicited by stimulation of the ipsilateral cervical vagus. These results suggest that the ECN is a site of origin of cardioinhibitory axons in the cat.

Animals↗