Posts tagged vasopressin
Articles and news from the latest research reports.
Neurons Can Use Local Stores for Communication Needs
Researchers reveal that neurons can utilize a supremely localized internal store of calcium to initiate the secretion of neuropeptides, one class of signaling molecules through which neurons communicate with each other and with other cells. The study appears in The Journal of General Physiology.
(Image caption: Localization of ryanodine receptors (red) in an isolated nerve terminal from the posterior pituitary gland. Image credit: McNally et al., 2014)
Neuropeptides are released from neurons through a process that—like other secretory events—is triggered primarily by the influx of calcium into the neuron through voltage-gated channels. Although neuropeptides are stored in large dense core vesicles (LDCVs) that also contain large amounts of calcium, it has been unclear whether these locally based calcium supplies can also be used to modulate secretion.
A team of researchers led by José Lemos from the University of Massachusetts Medical School examined the mechanisms at play during secretion of vasopressin from nerve terminals in the posterior pituitary gland, which releases the neuropeptide into the blood so that it can make its way to the kidney and regulate water retention. The researchers found that certain intracellular calcium channels known as ryanodine receptors are likely responsible for mobilizing calcium from LDCVs to facilitate vasopressin release. The findings indicate that neurons have a greater capacity than previously appreciated to fine-tune the release of neuropeptides and thereby their communications with other cells.
(Source: newswise.com)
Researchers find hormone vasopressin involved in jet lag
A team of researchers from several research centers in Japan has together found what appears to be a connection between the hormone vasopressin and jet-lag. In their paper published in the journal Science, the team describes experiments they conducted with test mice that indicate that repressing neural connections that respond to vasopressin reduced the time it took for them to readjust their circadian clock.
Adjustments to the circadian clock can be more than a nuisance for long distance flyers, research over the years has shown that it can cause stressed induced medical problems for those that work odd hours. For that reason, scientists have been looking for a way to reset the circadian clock much quicker than happens naturally. In this new effort the researchers looked at a part of the brain called the suprachiasmatic nucleus—it’s believed to be the main region involved in monitoring the passage of time and hence the circadian clock. Upon closer scrutiny, they found that many of the neurons in that part of the brain had receptors that were sensitive to vasopressin.
To find out why, they genetically altered test mice to inhibit such receptors and then artificially altered their day/night schedule. They found that without the receptors the mice were able to adjust to a radically altered time schedule in just one day, as opposed to the week or more it took unaltered mice. Next, they tried giving test mice a chemical that is known to block the same receptors, but only in the brain (neurons with vasopressin sensitive receptors are found throughout the nervous system) and found the mice were able to readjust their internal clocks in three days, much faster than normal, but still not as fast as those without the receptors.
The findings by the team suggest that a cure for jet-lag may be on the way. The chemical given to the mice has not been tested yet to see if it has other side-effects, most particularly, whether it causes problems with the kidneys—vasopressin is known to play a role in causing the kidneys to retain water to help regulate salt levels throughout the body.