Search results for "Melatonin"
showing 10 items of 165 documents
'TRPing' synaptic ribbon function in the rat pineal gland: neuroendocrine regulation involves the capsaicin receptor TRPV1.
2009
Synaptic ribbons (SRs) are presynaptic structures thought to regulate and facilitate multivesicular release. In the pineal gland, they display a circadian rhythm with higher levels at night paralleling melatonin synthesis. To gain more insight into the processes involved and the possible functions of these structures, a series of experiments were conducted in rodents. We studied the regional distribution of a molecular marker of pineal SRs, the kinesin motor KIF3A in the gland. Respective immunoreactivity was abundant in central regions of the gland where sympathetic fibers were less dense, and vice versa, revealing that intercellular communication between adjacent pinealocytes is enhanced …
Depressive effect of LHRH on the numbers of "synaptic" ribbons and spherules in the pineal gland of diestrous rats.
1983
Previous studies have shown that LHRH or LHRH-like substances are present in the pineal gland. In order to investigate whether exogenous LHRH may affect the pineal gland, in the present study the effects of a single dose of LHRH (1 microgram, i.p.) on pineal "synaptic" ribbons and spherules as well as serum melatonin levels were examined in diestrous Wistar rats. One hour after the injection both ribbons and spherules exhibited a statistically significant decrease in number. Serum melatonin levels were not affected. It is concluded that humoral feedback mechanisms may exist between the hypothalamus and the pineal gland.
In vitro effects of estradiol, testosterone, and progesterone on 5-methoxyindole content, cyclic adenosine 3',5'-monophosphate synthesis, and norepin…
1986
To examine the effects of estradiol, testosterone, or progesterone on cyclic adenosine 3',5'-monophosphate (AMP) accumulation, 5-methoxyindole levels, and norepinephrine (NE) release by the female guinea pig pineal complex, samples of the deep, intermediate, or superficial portions of the complex were incubated in vitro with varied concentrations of either hormone. Exposure for 10 minutes to physiological amounts of estradiol (10 nM) or to 100 microM NE increased significantly cyclic AMP levels to the same extent in the three pineal regions. A maximal effect on cyclic AMP accumulation was observed at 100-nM concentrations of estradiol, with a tendency to return to basal levels at 1-10 micro…
Zirkadiane Serotonin- und Melatonin-Serumspiegel bei Anorexia-nervosa-Patientinnen im Vergleich zu normal-menstruierenden Frauen
1996
Day and night rhythms of melatonin and serotonin were measured in four female anorexia nervosa patients and for comparison in a control group with normal 28-day menstrual cycle. In the anorexia nervosa group the levels of gonadotropins and sexual steroids were distinctly lowered. In the LHRH test the hormonal profile showed pubertal to prepubertal patterns of secretion with an only moderate increase of LH and distinct shifting of the LH/FSH ratio in direction of FSH. For both groups the 24-hour profiles of melatonin and serotonin showed a normal cycle, i.e. melatonin had its maximum by night, whereas serotonin in contrast displayed its highest values by day. However, in the group of patient…
Melatonin stimulates the nonamyloidogenic processing ofβAPP through the positive transcriptional regulation of ADAM10 and ADAM17
2014
Melatonin controls many physiological functions including regulation of the circadian rhythm and clearance of free radicals and neuroprotection. Importantly, melatonin levels strongly decrease as we age and patients with Alzheimer's disease (AD) display lower melatonin than age-matched controls. Several studies have reported that melatonin can reduce aggregation and toxicity of amyloid-β peptides that are produced from the β-amyloid precursor protein (βAPP). However, whether melatonin can directly regulate the βAPP-cleaving proteases ('secretases') has not been investigated so far. In this study, we establish that melatonin stimulates the α-secretase cleavage of βAPP in cultured neuronal an…
Lack of "Synaptic" Ribbons in the Pineal Gland of BALB/c Mice
1988
In mammalian pinealocytes "synaptic" ribbons (SR) are regularly occurring organelles that are functionally poorly understood. Since in a number of studies on the mouse pineal gland the presence of SR has not been mentioned, it was the aim of this investigation to quantitate SR in mice. BALB/c mice were chosen, which have recently been shown to have a genetic defect for melatonin synthesis. The pineals of 15 mice killed at night, when SR numbers are normally high, were examined electron microscopically, scanning an area of greater than 20,000 micron 2 per gland. In none of these pineals were SR detected. It is concluded that the lack or extreme rarity of SR in laboratory mice may be related …
Sleep Induction by Intranasal Application of Melatonin
1981
The sleep inducing potency of melatonin was tested in a double-blind study against placebo. The application form was a nasal spray with a 0.85% solution of melatonin in ethanol. 70% of the subjects fell asleep after treatment with the hormone.
Circadian variations of ?synaptic? bodies in the pineal glands of Brattleboro rats
1990
The function of the mammalian pineal gland is regulated primarily by the sympathetic system. Arginine-vasopressin (AVP) may also be involved in the regulation of pineal melatonin synthesis under experimental conditions. The present study was conducted in the AVP-deficient rat strain, the Brattleboro rat, to investigate whether the numbers and rhythms of pineal "synaptic" bodies in this strain are different from those found in intact rats. AVP or its non-vasoconstrictive analog, deamino-D-AVP, was also injected intra-arterially in Brattleboro or Sprague-Dawley rats to test whether this procedure influences "synaptic" body numbers. Brattleboro rats were killed at different time-points through…
Development of day-night rhythmicity in "synaptic" ribbon numbers in the pinealocytes of posthatch chicks kept under either natural photoperiodic con…
1991
: Pineal synaptic ribbons (SR) undergo characteristic changes over a period of 24 hr under natural photoperiodic conditions in various vertebrates, being low in number during daytime and elevated at night. During posthatch development of chicks, the rhythmicity of SR numbers is reported to appear at the age of about 2 weeks. Because the influence of external light during the growth phase of chicks on the development of day-night rhythmicity in SR numbers is unknown, we studied day-night differences in SR numbers in the pinealocytes of chicks at the posthatch ages of 15, 17, and 19 days; chicks had previously been kept under natural photoperiodic conditions or continuous illumination. Under …
Orientation and molecular contacts of melatonin confined into AOT and lecithin reversed micellar systems
2008
Abstract The state of increasing amounts of melatonin (MLT) confined in dry AOT or lecithin reversed micelles dispersed in CCl 4 has been investigated by UV–vis and 1 H NMR spectroscopies. The experimental results are consistent with MLT totally entrapped in reversed micelles, as a consequence of specific melatonin/surfactant interaction; the main driving force of the MLT solubilization in the core of reversed micelles is the establishment of H-bonding between the MLT NH groups (both indolic and amidic) and the head group of surfactants. The short contacts deduced from intermolecular NOEs are accounted for by favourable interactions between the surfactant's polar head and the H7–NH–H2 fragm…