The role of the hypothalamic paraventricular nuclei for the regulation of pineal melatonin synthesis: new aspects derived from the vasopressin-deficient Brattleboro rat

There is evidence for an involvement of the hypothalamic paraventricular nuclei (PVN) in the regulation of pineal melatonin synthesis in rats. Since electrical stimulation of the PVN or the systemic administration of arginine-vasopressin (AVP) result in a depression of the nocturnal melatonin surge, this neuropeptide appears to be pivotal for the transduction of PVN-efferent, pinealopetal signals. We therefore used an AVP-deficient animal model, the Brattleboro rat, to further investigate the mechanisms responsible for pineal regulation. Anesthetized adult male animals received 2 min of bilateral electrical stimulation of the PVN either during the day or at night. Thirty min later, pineal glands were removed and pineal N-acetyltransferase (NAT) activities and melatonin contents were determined. Stimulation resulted neither during the day nor at night in any significant alterations of pineal NAT activity or melatonin content when compared to control or sham-stimulated animals. These data further support the proposed modulatory role of AVP for the regulation of melatonin synthesis in the Epiphysis cerebri of genetically intact rats.     

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

Summary 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.Intrapineal stimulation and recording in the guinea-pig indicate functional connections between anterior and posterior parts of the pineal organ and that information can be conducted in both directions of the pineal axis.The data from the rat pineal gland are part of a thesis presented by St. Reuss in partial fulfillment for the degree of Dr. rer. nat. Preliminary data have been presented at the NATO Symposion The pineal gland and its endocrine role, Sicily 1982 (cf. Semm, 1983) and at the 6th European Neuroscience Congress, Malaga 1982 (cf. Reuss andSemm, 1982). — Financial support of the Stiftung Volkswagenwerk is gratefully acknowledged.     

Nitric oxide synthase in trigeminal ganglion cells projecting to the cochlea of rat and guinea pig

Nitric oxide (NO) influences electrophysiological and morphological parameters of the mammalian cochlea. Recently, the isoform of the NO-producing enzyme neuronal NO synthase (nNOS) has been demonstrated in spiral ganglion cells and olivocochlear neurons. The cochlea is also innervated by fibers stemming from the trigeminal ganglion (TG) and superior cervical ganglion (SCG). Whether these ganglion cells contain nNOS is not known yet. We therefore identified TG and SCG cells upon injection of Fluoro-Gold (FG) into the cochlea and retrograde neuronal transport of FG in rat and guinea pig. These ganglion cells were investigated for neuronal NOS immunohistochemically. Perikarya labeled by FG were found in the ipsilateral TG and SCG. In both species investigated, a considerable number of FG-labeled TG cells were also nNOS-immunoreactive whereas SCG cells were not. These data, demonstrating the existence of nNOS-containing TG cells that project to the cochlea, provide evidence that these neurons are further sources of nitric oxide in the cochlea.     

Survival and differentiation of dopaminergic mesencephalic neurons are promoted by dopamine-mediated induction of FGF-2 in striatal astroglial cells

Survival of dopaminergic (DAergic) midbrain neurons during development and after lesioning depends, in part, on the presence of astroglia-derived growth factors, as, e.g., fibroblast growth factor (FGF)-2. Astrocytes express DA receptors in a brain-region-specific manner. We show here that DA (10(-3) to 10(-6) mol/liter) applied continuously for 12 h or as a 10-min pulse significantly upregulates FGF-2 immunoreactivity quantified by Western blot and densitometry in astrocytes cultured from two target areas of DAergic neurons, striatum and cortex, but not in mesencephalic astroglia. Semiquantitative competitive RT-PCR confirmed the increase in FGF-2 on the mRNA level. The effects were specific in that glutamate, which can also activate receptors on astroglial cells, did not influence FGF-2 synthesis. In addition to the DA-mediated increase in FGF-2 synthesis the capability of conditioned medium (CM) from DA-stimulated striatal and cortical astrocytes to promote survival and process formation of cultured rat DAergic neurons was significantly enhanced. These effects could be fully blocked by preincubation of the CM with an FGF-2-specific polyclonal antiserum. Our results suggest that DA released from DAergic axon terminals in target regions of DAergic neurons and astroglial FGF-2 production are interdependent in that DA triggers synthesis of FGF-2, which, in turn enhances survival and differentiation of DAergic neurons.     

Sonography in Crohn disease--the conclusions of an experts' group

Sonography is adding a new dimension to diagnosis of Crohn's disease: the analysis of the transmural and peri-intestinal manifestations of the chronic inflammation. Distortions in the structure of intestinal wall are recognizable, the impact on transport of intestinal content can be judged, penetration of inflammation into the bowel surrounding as fistula, abscess, mesenteriitis und peritonitis is safely seen. Differential diagnosis on a strictly sonographic basis is difficult. The paper represents the results of an expert meeting held at the University of Frankfurt/M.     

Three methods for evaluation of left atrial volume.

AIM: To compare and contrast 3 different echocardiographic methods used to measure left atrial (LA) volume: biplane area length (AL), biplane modified Simpson (SIMP), and prolate ellipse (PE) methods. METHODS AND RESULTS: A review of consecutive patients who presented to our outpatient echocardiography laboratory for a resting transthoracic study between April 2006 and May 2006 was performed. Echocardiograms were reexamined and LA volume measured using the AL, SIMP, and PE methods. Of 102 consecutive patients evaluated, 97 had a measure of LA volume using all 3 methods. A significant difference in the measurement of mean +/- SD LA volume was noted among the 3 different methods: 37 +/- 16 mL/m(2) for AL, 34 +/- 14 mL/m(2) for SIMP, and 27 +/- 12 mL/m(2) for PE. The PE method yielded routinely smaller values compared with either the AL or SIMP method (P < 0.001). Differences increased with increased LA volume. The SIMP method derived consistently smaller (<5 mL/m(2)) values than those of the AL method, consistent across the full range of LA volumes. CONCLUSION: Significant differences exist among these 3 commonly used methods for measuring LA volume. Standardization of the measurement of LA volume is recommended.     

Smoking, alcohol and caffeine in relation to ovarian age during the reproductive years

BACKGROUND: We sought to determine whether smoking, alcohol and caffeine are related to four indicators of ovarian age: antral follicle count (AFC), follicle stimulating hormone (FSH), inhibin B and estradiol. METHODS: Analyses drew on ultrasound scans and sera from 188 women, aged 22-49. We used least squares regression to estimate differences in AFC and hormone levels for women who smoke cigarettes or who drink alcohol or caffeine. RESULTS: Current smoking is related to elevated FSH (beta for ln(FSH) = 0.21, 95% CI 0.04, 0.39), but not to AFC, inhibin B or estradiol. Neither alcohol nor caffeine is related to any ovarian age indicator. Exploratory analyses suggest that the association of current smoking with FSH varies with age: comparing current with never smokers, at ages 30, 35, 40 and 45, estimated differences in mean FSH are 0.3, 1.3, 3.2 and 6.9 mIU/ml. CONCLUSIONS: The association of current smoking with FSH may reflect accelerated oocyte atresia, impaired follicle quality or dysregulation of the hypothalamic-pituitary-ovarian axis. Identification of the causal mechanism has implications for prevention or treatment of conception delay, infertility and morbidity associated with early menopause.     

Biphasic effect of linoleic acid on connexin 46 hemichannels

Connexins form hemichannels at undocked plasma membranes and gap-junction channels (GJCs) at intercellular contacting zones. Under physiological conditions, hemichannels have low open probabilities, but their activation under pathological conditions, such as ischemia, induces and/or accelerates cell death. Connexin 46 (Cx46) is a major connexin of the lens, and mutations of this connexin induce cataracts. Here, we report the effects of linoleic acid (LA) on the electrical properties of Cx46 GJCs and hemichannels expressed in Xenopus laevis oocytes. LA has a biphasic effect, increasing hemichannel current at 0.1 μM and decreasing it at concentrations of 100 μM or higher. The effects of extracellular and microinjected LA conjugated to coenzyme A (LA-CoA) suggest that the current activation site is accessible from the intracellular but not extracellular compartment, whereas the current inhibitory site is either located in a region of the hemichannel pore inaccessible to intracellular LA-CoA, or requires crossing of LA through an organelle membrane. Experiments with other fatty acids demonstrated that the block of hemichannels depends on the presence of a hydrogenated double bond at position 9 and is directly proportional to the number of double bonds. Experiments in paired oocytes expressing Cx46 showed that LA does not affect GJCs. The block by unsaturated fatty acids reported here opens the possibility that increases in the concentration of these lipids in the lens induce cataract formation by blocking Cx46 hemichannels.     

Characterization of the Major Aroma-Active Compounds in Peel Oil of an HLB-Tolerant Mandarin Hybrid Using Aroma Extraction Dilution Analysis and Gas Chromatography-Mass Spectrometry/Olfactometry

Introduction

The main purposes of this study were to identity major peel oil odorants and determine which aroma compounds are primarily responsible for the overall aroma profile of a recently developed Huanglongbing (HLB)-tolerant mandarin hybrid.

Methods

The aroma-active compounds present in the recently developed mandarin hybrid peel oil were extracted by solvent-assisted flavor evaporation (SAFE) and then analyzed by gas chromatography-mass spectrometry/olfactometry (GC-MS/O) and aroma extract dilution analysis (AEDA).

Results

Thirty odor-active compounds in the flavor dilution (FD) factor range of 2 to 256 have been identified. On the basis of high FD factors, α-pinene, limonene, β-myrcene, linalool, and β-caryophyllene were characterized as the most essential aroma compounds at a FD factor ≥ 128, followed by γ-terpinene, β-pinene, terpinolene, p-dimethylstyrene, (E)-linalool oxide, decanal, β-cubebene, α-terpineol, and perilla aldehyde at a FD factor ≥ 16. Among all the detected aroma compounds, limonene was the most abundant compound (86.5 ± 2.8%), followed by γ-terpinene (5.3 ± 0.1%), β-myrcene (2.4 ± 0.1%), and α-pinene (1.2 ± 0.0%).

Conclusions

The compounds including α-pinene, limonene, β-myrcene, linalool, and β-caryophyllene were characterized as the most essential aromas. The sensory evaluation results indicated that the major attributes (FD ≥ 2) such as floral, lemon, peel-like, green, mint, and sweet were comparable to that of natural mandarin peel oil.

Implications

Based on the human perception, olfactometry and AEDA were used to determine the aroma-active compounds in the peel oil. Human perception also involved in aroma reconstitution to compare the re-engineering solution containing the essential aroma compounds with the natural mandarin oil.