The Organization of the Suprachiasmatic Circadian Pacemaker of the Rat and Its Regulation by Neurotransmitters and Modulators

Gillette, Martha U.; DeMarco, S. J.; Ding, Jian; Gallman, Eve A.; Faiman, Lia E.; Liu, C.; McArthur, Angela J.; Medanic, M.; Richard, Dominique; Tcheng, Thomas K.

doi:10.21236/ada266113

Cited by 7 publications

(6 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An additional means by which Mel may modulate food intake is via an action on the hypothalamic suprachiasmatic nucleus (SCN), a region rich in MT1 and MT2 Mel receptors ( 33 ). Mel modulation in the SCN is usually associated to its chronobiotic effects, controlling the mechanism of the circadian clock ( 34 – 36 ) acting through MT2. Additionally by acting on MT1, Mel modulates the firing rate of SCN neurons, modulating signal transmission down its projections pathways.…”

Section: Discussionmentioning

confidence: 99%

Melatonin Absence Leads to Long-Term Leptin Resistance and Overweight in Rats

et al. 2018

View full text Add to dashboard Cite

Melatonin (Mel), a molecule that conveys photoperiodic information to the organisms, is also involved in the regulation of energy homeostasis. Mechanisms of action of Mel in the energy balance remain unclear; herein we investigated how Mel regulates energy intake and expenditure to promote a proper energy balance. Male Wistar rats were assigned to control, control + Mel, pinealectomized (PINX) and PINX + Mel groups. To restore a 24-h rhythm, Mel (1 mg/kg) was added to the drinking water exclusively during the dark phase for 13 weeks. After this treatment period, rats were subjected to a 24-h fasting test, an acute leptin responsiveness test and cold challenge. Mel treatment reduced food intake, body weight, and adiposity. When challenged to 24-h fasting, Mel-treated rats also showed reduced hyperphagia when the food was replaced. Remarkably, PINX rats exhibited leptin resistance; this was likely related to the capacity of leptin to affect body weight, food intake, and hypothalamic signal-transducer and activator of transcription 3 phosphorylation, all of which were reduced. Mel treatment restored leptin sensitivity in PINX rats. An increased hypothalamic expression of agouti-related peptide (Agrp), neuropeptide Y, and Orexin was observed in the PINX group while Mel treatment reduced the expression of Agrp and Orexin. In addition, PINX rats presented lower UCP1 protein levels in the brown adipose tissue and required higher tail vasoconstriction to get a proper thermogenic response to cold challenge. Our findings reveal a previously unrecognized interaction of Mel and leptin in the hypothalamus to regulate the energy balance. These findings may help to explain the high incidence of metabolic diseases in individuals exposed to light at night.

show abstract

Section: Discussionmentioning

confidence: 99%

Melatonin Absence Leads to Long-Term Leptin Resistance and Overweight in Rats

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The 5-HT modulation of circuits and behaviors along phylogeny requires large amounts of transmitter molecules acting at different levels of the nervous system (Saller and Stricker, 1976; Willard, 1981; Lent, 1985; Raleigh et al, 1991; Gillette et al, 1993; Barnes and Jacklet, 1997; Hull et al, 1999; Kravitz, 2000; Prosser, 2003; Alekseyenko et al, 2010; Tomioka et al, 2012). Somatic exocytosis seems particularly well fitted for this function.…”

Section: Discussionmentioning

confidence: 99%

Exocytosis of serotonin from the neuronal soma is sustained by a serotonin and calcium-dependent feedback loop

Leon-Pinzon

Cercós

Noguez

et al. 2014

Front. Cell. Neurosci.

View full text Add to dashboard Cite

The soma of many neurons releases large amounts of transmitter molecules through an exocytosis process that continues for hundreds of seconds after the end of the triggering stimulus. Transmitters released in this way modulate the activity of neurons, glia and blood vessels over vast volumes of the nervous system. Here we studied how somatic exocytosis is maintained for such long periods in the absence of electrical stimulation and transmembrane Ca2+ entry. Somatic exocytosis of serotonin from dense core vesicles could be triggered by a train of 10 action potentials at 20 Hz in Retzius neurons of the leech. However, the same number of action potentials produced at 1 Hz failed to evoke any exocytosis. The 20-Hz train evoked exocytosis through a sequence of intracellular Ca2+ transients, with each transient having a different origin, timing and intracellular distribution. Upon electrical stimulation, transmembrane Ca2+ entry through L-type channels activated Ca2+-induced Ca2+ release. A resulting fast Ca2+ transient evoked an early exocytosis of serotonin from sparse vesicles resting close to the plasma membrane. This Ca2+ transient also triggered the transport of distant clusters of vesicles toward the plasma membrane. Upon exocytosis, the released serotonin activated autoreceptors coupled to phospholipase C, which in turn produced an intracellular Ca2+ increase in the submembrane shell. This localized Ca2+ increase evoked new exocytosis as the vesicles in the clusters arrived gradually at the plasma membrane. In this way, the extracellular serotonin elevated the intracellular Ca2+ and this Ca2+ evoked more exocytosis. The resulting positive feedback loop maintained exocytosis for the following hundreds of seconds until the last vesicles in the clusters fused. Since somatic exocytosis displays similar kinetics in neurons releasing different types of transmitters, the data presented here contributes to understand the cellular basis of paracrine neurotransmission.

show abstract

“…In these animals, there tended to be some sparing of the rostral ventrolateral portions of the SCN. In an elegant series of electrophysiological experiments designed to determine if the pacemaking properties of the SCN in laboratory rats are distributed throughout the nuclei, Gillette et al (1993) reported that isolation of the ventrolateral SCN from the dorsomedial SCN resulted in normal neuronal activity in the former in an in vitro slice preparation, but not in the latter. These in vitro data seem to support the in vivo findings in the present experiment.…”

Section: Time Of Infusion (Wk) 6cmentioning

confidence: 99%

The Effects of Anterior Hypothalamic Lesions on Short-Day Responses in Siberian Hamsters Given Timed Melatonin Infusions

Song¹,

Bartness

1996

J Biol Rhythms

View full text Add to dashboard Cite

The suprachiasmatic nucleus (SCN) of the hypothalamus is an area of dense 2-[125I]Iodomelatonin binding in Siberian hamsters (Phodopus sungorus sungorus) that is suggestive of a possible role in the reception and/or relaying of melatonin (MEL) signals. Indeed, in pinealectomized male Siberian hamsters given short day (SD) MEL signals (long-duration MEL infusions), lesions of the SCN (SCNx) block testicular regression and decreases in body and fat pad masses seen in identically treated hamsters with sham lesions (SCNs). In similar studies using Syrian hamsters (Mesocricetus auratus), anterior hypothalamic lesions (AHx), but not SCNx, blocked SD MEL signal-induced gonadal regression despite the similarity in the 2-[125I]Iodomelatonin binding pattern between the two species. The discrepancy between the ability of SCNx to block the reception of SD MEL signals between the two species is puzzling, given the similarity in the reproductive status of the Syrian and Siberian hamsters to systemically administered and timed MEL infusions. One possible way of reconciling the differences between these studies was that ancillary damage to areas neighboring the SCN, including the AH, may have occurred in our attempt to achieve complete SCNx in Siberian hamsters. Therefore, the purpose of the present study was to challenge AHx Siberian hamsters with SD MEL signals. Adult male hamsters were pinealectomized, fitted with subcutaneous catheters, and given daily timed infusions of MEL for 5 or 10 h (long day-like and short day-like, respectively) or the saline vehicle for 6 wk following bilateral electrolytic, or sham (AHs) lesions of the AH. Hamsters receiving 10 h MEL infusions that lacked evidence of anatomical or functional damage to the SCN showed SD-like gonadal regression, decreases in body and fat pad mass, and food intake similar to that observed in AHs animals. In contrast, 10 h MEL-infused SCNx hamsters did not exhibit SD-like responses, a finding confirming our previous report. These data suggest that interspecies differences exist between Syrian and Siberian hamsters in central nervous system sites and pathways involved in the reception/transmission of SD MEL signals.

show abstract

The Organization of the Suprachiasmatic Circadian Pacemaker of the Rat and Its Regulation by Neurotransmitters and Modulators

Cited by 7 publications

References 21 publications

Melatonin Absence Leads to Long-Term Leptin Resistance and Overweight in Rats

Melatonin Absence Leads to Long-Term Leptin Resistance and Overweight in Rats

Exocytosis of serotonin from the neuronal soma is sustained by a serotonin and calcium-dependent feedback loop

The Effects of Anterior Hypothalamic Lesions on Short-Day Responses in Siberian Hamsters Given Timed Melatonin Infusions

Contact Info

Product

Resources

About