Involvement of cyclic guanosine monophosphosphate (cGMP) and cytosolic guanylate cyclase in the regulation of synaptic ribbon numbers in rat pineal gland

Spessert, Rainer; Gupta, B. B. P.; Seidel, André; Maitra, Saumen Kumar; Vollrath, Lutz

doi:10.1016/0006-8993(92)90586-x

Cited by 28 publications

(14 citation statements)

References 22 publications

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“…Further studies in the rat pineal gland, however, demonstrated a high density of GC-B receptors (not GC-A), whose activation induced a large increase in cGMP levels (Mü ller et al, 2000). These observations, however, were not confirmed (Spessert et al, 1992). The bovine pineal gland also expresses GC-A and GC-B receptors, activation of which also increases the intracellular concentration of cGMP (Middendorff et al, 1996).…”

Section: Multiple Regulation Of Pineal Melatonin Synthesis In Mammalsmentioning

confidence: 95%

“…Consequently, cGMP has no effect on the synthesis and release of MEL (Spessert et al, 1992;Lin et al, 1994). However, some effects of cGMP on pineal biochemistry have been reported.…”

Section: The Third Messengers/transcription Factorsmentioning

confidence: 99%

“…Other studies, however, have reported that SOM potentiates the NEinduced synthesis of MEL (Mess et al, 1991) or activates acetyl coenzyme A hydrolase by protein-thiol/disulfide exchange mechanisms (Namboodiri et al, 1982). The synthesis of SOM in some pineal cells suggests that this peptide could display paracrine effects on other pineal functions (for example, on the number of synaptic ribbons: Gupta et al, 1992). It is also proposed that SOM may be involved in pineal development and cell differentiation since the number of SOM-containing cells and the quantity of mRNA coding for this peptide (Mato et al, 1997) decrease from 8 to 15 days after birth in the rat pineal gland.…”

mentioning

confidence: 99%

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Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

2003

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Section: Multiple Regulation Of Pineal Melatonin Synthesis In Mammalsmentioning

confidence: 95%

“…Consequently, cGMP has no effect on the synthesis and release of MEL (Spessert et al, 1992;Lin et al, 1994). However, some effects of cGMP on pineal biochemistry have been reported.…”

Section: The Third Messengers/transcription Factorsmentioning

confidence: 99%

mentioning

confidence: 99%

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Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

2003

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“…It should be noted though that differences appear to exist between young and adult rats. In young Sprague-Dawley rats of 120-140 g body weight, the injection of the [3-adrenergic receptor agonist isoproterenol almost doubled SR numbers (McNulty et al, 1989), while in adult rats of 200-500 g body weight no hint regarding an adrenergically regulated increase of SR numbers was obtained (Seidel et al, 1990 b;Spessert et al, 1992), based on the use of [3-adrenergic agonists and antagonists, NE as well as phenyl-nephrine, in vivo and/or in vitro. In view of the discrepancy of our results with those of McNulty et al (1989) we have repeated their isoproterenol experiment with rats of 120-140g and 240-280g body weight and found that, in vivo, isoproterenol increased SR numbers in the first, but not the second group (unpublished observations).…”

Section: Synaptic Ribbon Numbersmentioning

confidence: 96%

“…These observations were corroborated by in vitro studies in which norepinephrine (NE) stimulated melatonin synthesis in a dosedependent manner, but did not increase SR numbers (Seidel etal., 1990b). Moreover, in vitro, simultaneous stimulation of ~-and 13-adrenergic receptors with phenylephrine plus isoproterenol was without effect on SR numbers (Spessert et al, 1992). Hence, to gain insight into the regulatory mechanisms of pineal SR, in the present study pineal glands were incubated with pineal-related neurotransmitters/-peptides.…”

Section: Introductionmentioning

confidence: 98%

In vitro effects of putative neurotransmitters on synaptic ribbon numbers and N-acetyltransferase activity in the rat pineal gland

Gupta

Seidel

Spessert

et al. 1992

J. Neural Transmission

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The pineal contains a large number of classical transmitters and neuropeptides. Some of these neurochemicals are involved in the regulation of serotonin N-acetyltransferase (NAT) activity and hence in melatonin synthesis. Synaptic ribbons present in the pineal gland also exhibit a numerical day/night rhythm parallel to that of NAT activity. There is scarcity of information regarding the regulation of synaptic ribbon (SR) numbers. In the present study, we have investigated in vitro effects of a number of classical neurotransmitters and neuropeptides. NAT activity was used to monitor melatonin synthesis under the experimental conditions used. Norepinephrine (NE), Delta sleep-inducing peptide (DSIP), vasoactive intestinal polypeptide (VIP), adenosine and N-acetyl-asp-glu (NAAG) significantly increased NAT activity in rat pineal. DSIP and VIP also increase the stimulatory effect of NE on NAT activity. These neurochemicals had no effect on SR numbers. Gamma aminobutyric acid (GABA), serotonin and taurine affected neither NAT activity nor SR. Somatostatin increased SR numbers significantly, without having any effect on NAT activity. The effect of somatostatin is regarded to be pharmacologic, since rather high dosages (10(-4) M) were required to obtain a significant effect. Although somatostatin is present in the pineal and may change rhythmically, the inconsistency of the day/night rhythmicity and the lack of such a rhythm in female rats and male gerbils speaks against an important physiological role of somatostatin in regulating SR numbers.

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Plasticity of retinal ribbon synapses

Vollrath

Spiwoks-Becker

1996

Microsc. Res. Tech.

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Ribbon synapses differ from conventional chemical synapses in that they contain, within the cloud of synaptic vesicles (SV's), a specialized synaptic body, most often termed synaptic ribbon (SR). This body assumes various forms. Reconstructions reveal that what appear as rod‐ or ribbon‐like profiles in sections are in fact rectangular or horseshoe‐shaped plates. Moreover, spherical, T‐shaped, table‐shaped, and highly pleomorphic bodies may be present. In mammals, ribbon synapses are present in afferent synapses of photoreceptors, bipolar nerve cells, and hair cells of both the organ of Corti and the vestibular organ. Synaptic ribbons (SR's) are also found in the intrinsic cells of the third eye, the pineal gland, and in the lateral line system. The precise function of SR's is enigmatic. The prevailing concept is that SR's function as conveyor belts to channel SV's to the presynaptic membrane for neurotransmitter release by means of exocytosis. The present article reviews the evidence that speaks for a plasticity of these organelles in the retina and the third eye, as reflected in changes in number, size, shape, location, and grouping pattern. SR plasticity is especially pronounced in the mammalian and submammalian pineal gland and in cones and bipolar cells of teleost fishes. Here, SR number and size wax and wane according to the environmental lighting conditions. In the pineal SR numbers increase at night and decrease during the day. In teleost cones, SR's are in their prime during daytime and decrease or disappear at night, when transmitter release is enhanced. In addition to numerical changes, SR's may also exhibit changes in size, shape, grouping pattern, and location. In the mammalian retina of adults, in contrast to the developing retina, the reported signs of SR plasticity are subtle and not always consistent. They may reflect changes in function or may represent signs of degradation. To distinguish between the two, more detailed studies under selected experimental conditions are required. Probably the strongest evidence for SR plasticity in the mammalian retina is that in hibernating squirrels SR's leave the synaptic site and accumulate in areas as far as 5 μm from the synapse. Changes in shape include the occurrence of club‐shaped SR's and round SR's or synaptic spheres (SS's). SS's may represent a special type of synaptic body, yet belonging to the family of SR's, or may be related to the catabolism of SR's. SR number is regulated by Ca2+ in teleost cones, whereas in the mammalian pineal gland cGMP is involved. An interesting biochemical feature of ribbon synapses is that they lack synapsins. The presently reviewed results suggest to us that SR's do not primarily function as conveyor belts, but are devices to immobilize SV's in inactive ribbon synapses. © 1996 Wiley‐Liss, Inc.

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Involvement of cyclic guanosine monophosphosphate (cGMP) and cytosolic guanylate cyclase in the regulation of synaptic ribbon numbers in rat pineal gland

Cited by 28 publications

References 22 publications

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

In vitro effects of putative neurotransmitters on synaptic ribbon numbers and N-acetyltransferase activity in the rat pineal gland

Plasticity of retinal ribbon synapses

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