Lack of circadian patterns in vasoactive intestinal polypeptide release and variability in vasopressin release in vole suprachiasmatic nuclei in vitro

1999 ◽  
Vol 259 (2) ◽  
pp. 107-110 ◽  
Author(s):  
Menno P. Gerkema ◽  
Kazuyuki Shinohara ◽  
Fukuko Kimura
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Suprachiasmatic Nuclei ◽  
Vasopressin Release ◽  
Circadian Patterns ◽  
Intestinal Polypeptide

Effects of Vasoactive Intestinal Polypeptide on Neurones of the Rat Suprachiasmatic Nuclei In Vitro

2002 ◽  
Vol 14 (8) ◽  
pp. 639-646 ◽  
Author(s):  
H. E. Reed ◽  
D. J. Cutler ◽  
T. M. Brown ◽  
J. Brown ◽  
C. W. Coen ◽  
...  
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Suprachiasmatic Nuclei ◽  
Intestinal Polypeptide

scholarly journals The roles of vasoactive intestinal polypeptide in the mammalian circadian clock

2003 ◽  
Vol 177 (1) ◽  
pp. 7-15 ◽  
Author(s):  
HD Piggins ◽  
DJ Cutler
Keyword(s):  
Circadian Clock ◽  
Vasoactive Intestinal Polypeptide ◽  
Chemical Constituents ◽  
Neural Pathways ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Environmental Signals ◽  
Intestinal Polypeptide

Biological oscillations with an endogenous period of near 24 h (circadian rhythms) are generated by the master circadian pacemaker or clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus. This clock is synchronised to recurring environmental signals conveyed by selective neural pathways. One of the main chemical constituents of SCN neurones is vasoactive intestinal polypeptide (VIP). Such neurones are retinorecipient and activated by light. Exogenous application of VIP resets the SCN circadian clock in a light-like manner, both in vivo and in vitro. These resetting actions appear to be mediated through the VPAC2 receptor (a type of receptor for VIP). Unexpectedly, genetically ablating expression of the VPAC2 receptor renders the circadian clock arrhythmic at the molecular, neurophysiological and behavioural levels. These findings indicate that this intrinsic neuropeptide acting through the VPAC2 receptor participates in both resetting to light and maintenance of ongoing rhythmicity of the SCN.

scholarly journals Disrupted Neuronal Activity Rhythms in the Suprachiasmatic Nuclei of Vasoactive Intestinal Polypeptide-Deficient Mice

2007 ◽  
Vol 97 (3) ◽  
pp. 2553-2558 ◽  
Author(s):  
T. M. Brown ◽  
C. S. Colwell ◽  
J. A. Waschek ◽  
H. D. Piggins
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Wheel Running ◽  
Brain Slices ◽  
Suprachiasmatic Nuclei ◽  
Wild Type ◽  
Behavioral Rhythms ◽  
Adult Mice ◽  
Deficient Mice ◽  
Intestinal Polypeptide

Vasoactive intestinal polypeptide (VIP), acting via the VPAC2 receptor, is a key signaling pathway in the suprachiasmatic nuclei (SCN), the master clock controlling daily rhythms in mammals. Most mice lacking functional VPAC2 receptors are unable to sustain behavioral rhythms and lack detectable SCN electrical rhythms in vitro. Adult mice that do not produce VIP (VIP/PHI−/−) exhibit less severe alterations in wheel-running rhythms, but the effects of this deficiency on the amplitude, phasing, or periodicity of their SCN cellular rhythms are unknown. To investigate this, we used suction electrodes to extracellularly record multiple- and single-unit electrical activity in SCN brain slices from mice with varying degrees of VIP deficiency, ranging from wild-type (VIP/PHI+/+) to heterozygous (VIP/PHI+/−) and VIP/PHI−/− animals. We found decreasing proportions of rhythmic cells in SCN slices from VIP/PHI+/+ (∼91%, n = 23) through VIP/PHI-/+ (∼71%, n = 28) to VIP/PHI−/− mice (62%; n = 37) and a parallel trend toward decreasing amplitude in the remaining rhythmic cells. SCN neurons from VIP/PHI−/− mice exhibited a broad range in the period and phasing of electrical rhythms, concordant with the known alterations in their behavioral rhythms. Further, treatment of VIP/PHI−/− slices with a VPAC2 receptor antagonist significantly reduced the proportion of oscillating neurons, suggesting that VPAC2 receptors still become activated in the SCN of these mice. The results establish that VIP is important for appropriate periodicity and phasing of SCN neuronal rhythms and suggest that residual VPAC2 receptor signaling promotes rhythmicity in adult VIP/PHI−/− mice.

scholarly journals Participation of vasoactive intestinal polypeptide in ovarian steroids production during the rat estrous cycle and in the development of estradiol valerate-induced polycystic ovary

Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 147-154 ◽  
Author(s):  
Claudio Parra ◽  
Jenny L Fiedler ◽  
S Leticia Luna ◽  
Monika Greiner ◽  
Vasantha Padmanabhan ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Vasoactive Intestinal Polypeptide ◽  
Polycystic Ovary ◽  
Secretory Activity ◽  
Estradiol Valerate ◽  
Steroid Secretion ◽  
Cyclic Changes ◽  
Intestinal Polypeptide

Vasoactive intestinal polypeptide (VIP) stimulates estradiol and progesterone release from ovarian granulosa cells in vitro. Very little information is available as to the role VIP plays in the control of steroid secretion during reproductive cyclicity and in ovarian pathologies involving altered steroid secretion. In this study, we determined the involvement of VIP in regulating ovarian androgen and estradiol release during estrous cyclicity and estradiol valerate (EV)-induced polycystic ovarian development in rats. Our findings show that androgen and estradiol release from ovaries obtained during different stages of rat estrous cycle mimic cyclic changes in steroid release observed in vivo with maximal release occurring during late proestrus. VIP increased androgen release from ovaries of all cycle stages except late proestrus and estradiol release from all cycle stages. Increases in VIP-induced androgen and estradiol release were maximal at early proestrus. Inclusion of saturating concentrations of androstenedione increased magnitude of VIP-induced estradiol release at diestrus and estrus but not proestrus. Magnitude of VIP-induced androgen and estradiol release tended to be greater in the ovaries from EV-treated rats with polycystic ovary compared with estrous controls. At the tissue level, ovarian VIP concentration was cycle stage dependent with highest level seen in diestrus. Maximum concentration of VIP was found in EV-treated rats. Changes in VIP were inversely related to changes in ovarian nerve growth factor, a neuropeptide involved in ovarian androgen secretion. These results strongly suggest that intraovarian VIP participates in the control of estradiol secretion during the rat estrous cycle and possibly in the maintenance of increased ovarian estradiol secretory activity of EV-treated rats.

Reversal of nerve damage in streptozotocin-diabetic rats by acute application of insulin in vitro

1988 ◽  
Vol 75 (6) ◽  
pp. 629-635 ◽  
Author(s):  
Geoffrey Burnstock ◽  
Rhona Mirsky ◽  
Abebech Belai
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Calcitonin Gene Related Peptide ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Rat Ileum ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Enteric Nerves ◽  
Intestinal Polypeptide

1. Immunohistochemical, immunoblotting and release experiments were performed on ileum from control rats, from 8-week streptozotocin-diabetic rats and from diabetic rats after acute application of insulin in vitro. 2. There was an increase in vasoactive-intestinal-polypeptide-like and a decrease in calcitonin-gene-related-peptide-like immunoreactivity in the myenteric plexus of the diabetic rat ileum, although electrically evoked release of both peptides from enteric nerves was defective. Acute application of insulin in vitro reversed the defective release and changes in immunoreactivity of vasoactive intestinal polypeptide and calcitonin-gene-related peptide seen in the enteric nerves of streptozotocin-diabetic rat ileum. 3. In addition, using a monoclonal neurofilament antibody RT 97 that recognizes a phosphorylated neurofilament epitope present in normal enteric nerves, it was shown that this phosphorylated neurofilament epitope was absent in diabetic nerves, even though a polyclonal neurofilament antibody revealed that neurofilaments were present in both axons and cell bodies of the myenteric plexus of diabetic rat ileum. After only 2 h of insulin incubation in vitro, the phosphorylated neurofilament epitope was again present in the nerves. 4. It is suggested that the abnormal distribution of phosphorylated neurofilaments and defective storage and release of vasoactive intestinal polypeptide and calcitonin-gene-related peptide in the present study may be a more general feature of diabetes. The restoration of these abnormalities by continuous acute insulin application in vitro shown here suggests that the availability of a steady level of insulin might prevent some of the changes which occur in early stages of diabetes. If so, this could influence the use of insulin in the treatment of diabetes, particularly in view of the recent report that short-term continuous subcutaneous insulin infusion restores the function of the autonomic and peripheral nerves in type I diabetic patients [Krönert, K., Hülsen, J., Luft, D., Stetter, T. & Eggstein, M. (1987) Journal of Clinical Endocrinology and Metabolism, 64, 1219–1223].

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