Search results for "Pineal Gland"
showing 10 items of 143 documents
Transcriptional regulation of nucleoredoxin-like genes takes place on a daily basis in the retina and pineal gland of rats.
2015
AbstractThe nucleoredoxin-like gene Nxnl1 (Txnl6) and its paralogue Nxnl2 encode the rod-derived cone viability factors (RdCVF and RdCVF2), which increase the resistance to photooxidative damage and have therapeutic potential for the survival of cones in retinitis pigmentosa. In this study, the transcription of Nxnl genes was investigated as a function of the day/night cycle in rats. The transcript levels of Nxnl1 and Nxnl2 were seen to display daily rhythms with steadily increasing values during the light phase and peak expression around dark onset in preparations of whole retina, photoreceptor cells and—but only in regard to Nxnl1—in photoreceptor-related pinealocytes. The cycling of Nxnl…
Effect of pinealectomy and circadian rhythm on avoidance behavior in the male rat.
1985
Male adult albino rats were divided into six groups: two pinealectomized (Px); two sham-operated (Sh) and two serving as controls (C). Half of these groups were studied in daylight and the other half at night. The animals were open-field tested and then conditioned by the avoidance behavior test in the appropriate light period. No differences were observed among the groups when they were conditioned in the dark; however, the Px were conditioned significantly more rapidly than Sh or C in daylight. Intragroup comparisons between night/day conditioning showed them to be similar in Px but more rapid at night in both Sh and C. The Sh group is unique and not comparable to controls.
Distribution of dopamine-beta-hydroxylase—like immunoreactivity in the rat pineal organ
1985
The aim of the present investigation was to study the distribution in the rat pineal gland of dopamine-beta-hydroxylase (DBH) which is essential for the formation of the melatonin synthesis-regulating substance noradrenaline (NA). In 5- and 8-month-old male Sprague-Dawley rats DBH-like immunoreactivity (DBH-LI) was studied using polyclonal antibodies against DBH and the indirect immunofluorescent technique. DBH-LI was mainly located in pineal nerve fibres coming from the superior cervical ganglia. The intensity of the staining reaction was considerably lower than in non-pineal noradrenergic nerve fibres and the impression was gained by comparison of DBH-LI specimens with glyoxylic acid-trea…
Electrophysiological characterization of the pineal gland of golden hamsters.
1987
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…
Principal neurons projecting to the pineal gland in close association with small intensely fluorescent cells in the superior cervical ganglion of rats
1988
The localization in the superior cervical ganglia (SCG) of small, intensely fluorescent (SIF) cells and of principal nerve (PN) cells innervating the pineal gland was examined in adult male Sprague-Dawley rats. PN cells were demonstrated by means of the retrograde neuron-tracing method using the fluorescent tracer Fluoro-Gold (FG) injected into the pineal gland. SIF cells were visualized by the formaldehyde-induced fluorescence method. Twenty-nine percent of the FG-labeled PN cells were found closely associated with SIF cells. In the rostral half of the ganglion, 43% of the SIF cells were situated in juxtaposition to one or several labeled neurons. The possible influence of SIF cells on the…
Epinephrine Preworkout Elevation May Offset Early Morning Melatonin Concentrations to Maintain Maximal Muscular Force and Power in Track Athletes
2014
The optimal time of day for training has become an important question for many strength and conditioning specialists, and this study was designed to add some insights into this complex question. The primary purpose of this investigation was to examine physical performance within the temporal context of the relationship between physical performance, epinephrine, and melatonin concentrations in the early morning (0530 hours) and late (1500 hours) afternoon in elite collegiate male track and field athletes (jumpers and sprinters). Subjects had a mean (±SD) age, height, and body mass of 20.4 (±1.6) years, 185.8 (±9.4) cm, and 77.9 (±8.5) kg, respectively. Blood was obtained before each AM and P…
Biphasic 24-Hour Variations in Cyclic GMP Accumulation in the Rat Pineal Gland Are Due to Corresponding Changes in the Activity of Cytosolic and Part…
2006
Various parameters of the rat pineal gland display a 24-h rhythm. However, nothing is known about possible 24-h variations in cyclic GMP (cGMP) metabolism. In the present study, 24-h variations in pineal gland cGMP accumulation were investigated by determining the increase in cGMP level with and without inhibitors of phosphodiesterase at different time points over a light/dark cycle (12/12 h). Furthermore, the activity of guanylate cyclase (GC) was determined under substrate-saturated conditions regarding the cytosolic and particulate forms of the enzyme. It has been found that cGMP accumulation and GC activity display biphasic 24-h variations with two peaks--one approximately 7 h after lig…
Components and connections of the circadian timing system in mammals
1996
The circadian timing system is a neural network consisting of the hypothalamic suprachiasmatic nucleus, aided by the retina, other hypothalamic nuclei, autonomic regions of the spinal cord, sympathetic ganglia and the pineal gland. Extensive studies conducted over the last two decades have unravelled the principal items of its functional neuroanatomy. The system is responsible for the generation of the circadian rhythm, its synchronization by environmental factors such as light, and its mediation with respect to morphological, physiological and biochemical parameters of mammals that exhibit distinct alterations throughout the 24-h cycle. This review characterizes the brain sites involved an…
Chronoendokinologia — Quo vadis?
2002
The present review deals with important new chronobiological results especially in the field of chronoendocrinology, shedding new light on the circadian organisation of mammals including man. In vitro studies have shown that the concept of the existence of a single circadian oscillator located in the suprachiasmatic nucleus has to be extended. Circadian oscillators have also been found to exist in the retina, islets of Langerhans, liver, lung, and fibroblasts. Another major result is the detection of a new photopigment, melanopsin, present in a subpopulation of retinal ganglion cells which are lightsensitive and project to the suprachiasmatic nucleus, acting as zeitgeber for the photic entr…
Circadian gene expression patterns of melanopsin and pinopsin in the chick pineal gland
2004
The directly light-sensitive chick pineal gland contains at least two photopigments. Pinopsin seems to mediate the acute inhibitory effect of light on melatonin synthesis, whereas melanopsin may act by phase-shifting the intrapineal circadian clock. In the present study we have investigated, by means of quantitative RT-PCR, the daily rhythm of photopigment gene expression as monitored by mRNA levels. Under a 12-h light/12-h dark cycle, the mRNA levels of both pigments were 5-fold higher in the transitional phase from light to dark than at night, both in vivo and in vitro. Under constant darkness in vivo and in vitro, the peak of pinopsin mRNA levels was attenuated, whereas that of melanopsi…