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S Reuss

Publications and source records attributed to S Reuss.

At least 91 records · Page 5Linked to original sources
PubMed1987

Electrophysiological characterization of the pineal gland of golden hamsters.

In one of the most-widely used species in pineal gland research, the strongly photoperiodic golden hamster, Mesocricetus auratus, no electrophysiological data on pinealocytes are currently available. To fill this gap, in the present study 185 spontaneously active pinealocytes from male golden hamsters were recorded extracellularly, both during day- and night-time (light: dark cycle 12: 12, lights on at 07.00 h). As in other species, pinealocytes exhibited action potentials of 1-2 ms duration. An irregular firing pattern was observed in 95% of the pinealocytes, the remainder fired more regularly or showed a phasic discharge pattern. The firing frequencies ranged from 0.2 to 25 Hz and showed clear time-dependent differences. From 07.00 h to 22.00 h the mean firing frequencies were identical, i.e. in the range of 2 Hz; between 22.00 h and 01.00 h mean discharge rate increased to 5 Hz and exhibited a peak of 7 Hz between 01.00 h and 04.00 h, followed by a decrease to 4 Hz between 04.00 h and 07.00 h. Electrical stimulation of the superior cervical ganglion during day-time resulted in an augmentation of firing frequency in some pinealocytes and a decrease in others; during night-time, inhibitory responses only were observed. Photic stimulation, or electrical stimulation of either the optic chiasm or the habenular nuclei mostly decreased the firing rate of pinealocytes. Compared to other mammalian species, the electrophysiological properties of golden hamster pinealocytes appear to be basically similar.

Action Potentials↗
PubMed1986

Lamina-specific differences of visual latencies following photic stimulation in the cat striate cortex.

Vertical penetrations were made in the part of the cat's area 17 subserving central vision. Single units were recorded every 100-200 micron and the recording sites histologically reconstructed. Visual latencies of complex cells following whole-field ON/OFF stimulation were determined as a function of cortical depth. The shortest latencies were found for cells in layers IV and VI (mean ON response 44 ms/OFF response 51 ms for IV and 43 ms/42 ms for VI). In contrast, mean latencies in layer V were 54 ms/57 ms, while cells of the supragranular layers had the longest mean latencies of 62 ms/73 ms. Furthermore, this analysis revealed significant differences of between 10 and 30 ms on the average between the individual layers (the differences between individual cells can even be in the range of more than 60 ms). These differences cannot easily be explained by conduction time and synaptic delays, which both can account for a few ms only. One possible explanation is based on a dynamic model of intracortical information processing with multiple positive feedback loops.

Animals↗
PubMed1986

Magnetic field effects on pineal gland melatonin synthesis: comparative studies on albino and pigmented rodents.

Previous investigations have shown that the inhibitory effects of an earth-strength magnetic field on albino rat pineal melatonin synthesis is dependent on optic input. The possibility that ocular pigmentation might play a role in mammalian magnetosensitivity was explored in the present study by comparing hooded rat and golden hamsters with albino rats. Pineal melatonin synthesis, i.e. N-acetyl-transferase activity and melatonin content, was utilized as a parameter for assessing magnetosensitivity. In both rat strains nocturnal pineal melatonin synthesis was markedly inhibited following a single 30-min magnetic field stimulus consisting of a 50 degree rotation of the earth's field horizontal component. However, golden hamsters did not respond to the same magnetic stimulus, indicating a species-specific magnetosensitivity that is apparently independent of ocular pigmentation. Possible reasons for these differences are discussed.

Albinism↗
PubMed1986

Magnetic field effects on the rat pineal gland: role of retinal activation by light.

In view of the reported involvement of the retinae in mediating magnetic field effects on pineal function in rats, the present study sought to test the hypothesis - based on theoretical calculations - that dim light activation of photoreceptors is necessary for magnetoreception by the retinae. Adult male rats were exposed to a single nocturnal inversion of the earth's magnetic field in the presence or absence of dim red light. Pineal gland N-acetyltransferase and hydroxyindole-O-methyltransferase activities were measured as indices of magnetosensitivity. In animals exposed to dim red light, pineal enzyme activities were inhibited significantly by the magnetic stimulus in comparison to controls (dim red light only). In contrast, the pineal response to a magnetic stimulus was absent in total darkness. These results support the notion that photoreceptor stimulation by dim light is necessary for the perception of weak magnetic fields.

Acetylserotonin O-Methyltransferase↗
PubMed1986

Direct projections to the rat pineal gland via the stria medullaris thalami. An anterograde tracing study by use of horseradish peroxidase.

The possible presence of a direct nervous projection from the paraventricular nucleus (PVN) of the hypothalamus to the pineal gland of the rat was investigated by means of the anterograde neuron-tracing method using horseradish peroxidase. The tracer was injected unilaterally into the PVN and the animals were allowed to survive between 12 and 26 h. Numerous peroxidase-positive fibers were observed, ipsilateral to the injection site, in the stria medullaris thalami and could be followed into the medial habenular nucleus and the habenular commissure. From there, fibers penetrated into the deep pineal gland (lamina intercalaris), and further into the pineal stalk. These data support results of previous investigations describing retrograde labeling of the PVN following intrapineal injections of horseradish peroxidase and are in accordance with recent experiments demonstrating an influence of the PVN on electrical and biochemical activity of the pineal gland.

Afferent Pathways↗
PubMed1986

Effects of chemical and surgical ganglionectomy on electrical activity of the pineal gland of male rats.

In order to elucidate further the role of sympathetic innervation for pineal function, the influence of sympathectomy on the spontaneous electrical activity of single cells in the pineal gland of adult male rats was investigated. Extracellular single-unit recordings were made during nighttime in the pineal gland of urethane-anesthetized, blinded adult male rats that had been treated neonatally with 6-hydroxydopamine, or that were ganglionectomized either during, or 12-16 h or 36-40 h, prior to the recording experiment. These experiments revealed that the excitatory influence of the sympathetic system on pineal nocturnal electrical activity can be abolished by either chemical sympathectomy of neonatal rats or surgical superior cervical ganglionectomy in adult animals.

Animals↗
PubMed1986

Electrophysiological and endocrinological aspects of aging in the rat pineal gland.

Previous morphological and biochemical studies point to an age-dependent loss of pineal gland function. In order to investigate the possible alterations of electrical activity of aged rat pineal glands, electrophysiological recordings in 3- and 18-month-old male Sprague-Dawley rats were undertaken at both daytime and nighttime. Extracellularly recorded action potentials were characterized according to discharge frequency and serum melatonin levels were determined concomitantly. Significant differences in the frequency distributions between young adult and old rats were found to occur at nighttime, with a shift towards lower frequencies in old animals. Serum melatonin levels were reduced significantly in old rats and the characteristic nocturnal peak was attenuated. These results demonstrate a distinct decrease of pineal electrical and secretory activity with advancing age, which may contribute to an age-dependent decline of neuroendocrine capacity.

Action Potentials↗
PubMed1985

Evidence for the involvement of the visual system in mediating magnetic field effects on pineal melatonin synthesis in the rat.

In order to elucidate whether magnetic field effects on mammalian pineal function are direct, or instead indirect via retinal disturbances, acutely blinded and intact male rats were subjected to a single nocturnal magnetic stimulus. Then pineal N-acetyltransferase activity and melatonin content were assayed. Only in intact animals did the magnetic stimulus significantly reduce pineal activity, i.e. no effects were detected in blinded animals. These data point to a retinal magnetosensitivity which may serve to modulate pineal gland function.

Acetyltransferases↗
PubMed1985

Changes in the electrical activity of the rat pineal gland following stimulation of the cervical sympathetic ganglia.

In order to elucidate the role of sympathetic innervation for pineal function, the influence of both unilateral and bilateral electrical stimulation of the superior cervical ganglia on the electrical activity of single cells in the rat pineal gland was investigated. These experiments revealed a clear influence on spontaneous electrical activity of single pinealocytes. About half of the units tested by unilateral stimulation exhibited either a graded continuous augmentation or inhibitions of different magnitude. In addition, 'silent' cells without spontaneous activity could be activated by sympathetic stimulation. Sequential and simultaneous bilateral stimulations showed that only a few cells could be influenced by both ganglia and in these cases the influence seemed to be additive. Some pineal cells do not appear to be under the control of the sympathetic nervous system.

Animals↗
PubMed1985

Electrical stimulation of the hypothalamic paraventricular nuclei inhibits pineal melatonin synthesis in male rats.

Recent findings have shown that lesions of the hypothalamic paraventricular nuclei (PVN) disrupt the synthesis of melatonin in the rat pineal gland. In order to further clarify the role of the PVN in the control of pineal function, the effects of electrical stimulation of these nuclei were investigated in acutely blinded adult male Sprague-Dawley rats. Following electrical stimulation, pineal serotonin-N-acetyltransferase (NAT) activity and pineal melatonin content were measured by means of radioenzymatic and radioimmunoassay methods, respectively. Stimulation had no significant effect on pineal melatonin synthesis throughout the early part of the dark phase, but caused a significant reduction in NAT activity during the light phase and the latter part of the dark phase. The pineal melatonin content appeared reduced, but due to large individual variations this reduction was not statistically significant. Stimulation duration experiments reveal that reduction of NAT activity is time dependent, with significant inhibition occurring after 30 min of stimulation. These observations further support the involvement of the PVN in the melatonin rhythm generating pathway and suggest that electrical activation of fibers in the PVN is similar to the effects of light on pineal melatonin synthesis.

Animals↗
PubMed1984

Electrophysiological properties of rat pinealocytes: evidence for circadian and ultradian rhythms.

Extracellular single-unit recordings were made during day- and night-time in the pineal gland of urethane-anesthetized adult male Sprague-Dawley rats. All cells exhibiting spontaneous electrical activity had firing frequencies from less than 1 Hz to about 100 Hz, and their discharge patterns were characterized as regular, irregular or bursting. While most of the spontaneously active cells (n = 163) showed a uniform activity level throughout the recording period (30-120 min), a group of 9 cells exhibited oscillatory rhythms with periods of 4-8 min. In addition, long-term recordings across day- and night-time from five cells revealed increasing activity during night-time in three cells, while the remaining two units showed constant activity throughout the recording time (8-20 h). Comparison of day- and night-data in general indicated an overall higher level of activity at night.

Action Potentials↗
PubMed1984

Electrophysiological investigations on the central innervation of the rat and guinea-pig pineal gland.

The possible influence of central nervous structures on the electrical activity of single pineal cells was investigated in rat and guinea-pig. In the rat electrical stimulation of the hippocampal formation elicited both single cell responses with different latencies and mostly long-term excitations in single pineal cells, while stimulation of the habenular nuclei caused clear orthodromical responses with different latencies, alterations in the rate of spontaneous electrical activity and evoked discharges of "silent" units. In the guinea-pig electrical stimulation of the paraventricular nucleus influenced predominantly cells in the deeper layers of the posterior part of the pineal gland. Electrical stimulation of both the superior and inferior colliculi elicited field potentials with a constant latency, indicating a functional relationship between the corpora quadrigemina and the pineal organ.

Animals↗
PubMed1983

Different types of magnetically sensitive cells in the rat pineal gland.

Extracellular recordings from rat pinealocytes reveal different cell responses following experimental changes in the horizontal component of the ambient magnetic field. While two-thirds of the units recorded did not respond at all, one group is activated, the activation continuing after switching off the magnetic stimuli. These cells were not further activated by a second stimulus. Another group comprises cells characterized by a sustained inhibition or excitation, respectively, during magnetic stimulation. These cells could be influenced by a second stimulus. After guinea pigs and homing pigeons the rat is now the third species in which the pineal gland has been shown electrophysiologically to respond to changes of the ambient magnetic field.

Animals↗
PubMedDate not supplied

Trigeminal innervation of the mammalian pineal gland.

There is evidence that the trigeminal (Gasserian) ganglia innervate the mammalian pineal gland and serve in its regulation in addition to the sympathetic and cholinergic as well as further influences. By means of immunohistochemical methods, previous studies demonstrated fibers containing calcitonin gene-related peptide (CGRP-LI) or substance P (SP) in the superficial pineal of various mammalian species. In addition, SP and the related tachykinin, neurokinin A, were detected by radioimmunoassay and HPLC, respectively, in the rat and human pineal gland. In the present study, retrograde neuronal tracing upon injection of a tracer substance into the superficial pineal gland of rats was used in combination with immunohistochemistry to show that trigeminal ganglionic neurons innervate the gland, and that a considerable amount of these neurons are also CGRP- or SP-immunoreactive. These results reveal that afferent neuropeptidergic entering the superficial pineal gland originate from the trigeminal ganglia. The present paper reviews the evidence for a CGRP- and SP-ergic innervation of the mammalian pineal gland and discusses the possible role of these neuropeptides with regard to pineal function.

Animals↗
PubMedDate not supplied

Calcitonin gene-related peptide-like immunoreactivity in spinal cord and superior cervical ganglion of the Djungarian hamster (Phodopus sungorus).

The indirect immunofluorescent method was employed to investigate the distribution of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in the spinal cord and superior cervical ganglion of the Djungarian hamster Phodopus sungorus. In cross-sections of the spinal cord, immunoreactive fibres and terminals were found in laminae 1 and 2 in high density, in the dorsolateral (Lissauer's) tract, in ventral and lateral horns, and in the area surrounding the central canal. A few CGRP-LI perikarya were seen in the ventral but not the dorsal horn. CGRP-LI was further observed in preganglionic sympathetic neurons which were labelled by retrograde axonal transport of fluoro-gold (FG) following injection of the substance unilaterally into the superior cervical ganglion. Preganglionic sympathetic neurons (PSN) were localized ipsilateral to the injection site mainly in the intermediolateral nucleus and the lateral funiculus of the upper thoracic segments. Most PSN exhibited CGRP-LI. Immunoreactive PSN were not seen contralaterally to the site of FG application nor in animals that did not receive injections. When the preganglionic fibres were ligated 4 days before perfusion, CGRP-LI cell bodies were found in preganglionic sympathetic neurons similar to the situation seen upon FG treatment. In the superior cervical ganglia of untreated hamsters, immunoreactive fibres were seen to enter the ganglion in which they terminated at non-immunoreactive principal ganglion cells. The present study, the first in a hamster species, describes the widespread distribution of CGRP in the spinal cord of P. sungorus and supports the view that considerable interspecies differences exist in occurrence and location of this neuropeptide.

Animals↗