Evidence for a Brain Site of Melatonin Action in the White-Footed Mouse, &lt;i&gt;Peromyscus leucopus&lt;/i&gt;

Jd, Glass; Gr, Lynch

doi:10.1159/000123269

Cited by 105 publications

(64 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The six animals with misplaced cannulas constitute a control group for spread of Mel from the implant sites. The distance of spread observed from similar sized implants in previous experiments was 0.2 mm (14). The resulting number of animals per group were as follows; SCN: n ϭ 13 Mel, three misplaced Mel and three beeswax implants; NRE: n ϭ 10 Mel, one misplaced Mel, and three beeswax; PVT: n ϭ 8 Mel, two misplaced Mel, and four beeswax.…”

Section: Resultsmentioning

confidence: 87%

“…ref. 14) or beeswax alone. The internal cannulas were removed beginning on week 4 and every other week thereafter and repacked with fresh hormone or beeswax before being reinserted into the animal.…”

Section: Methodsmentioning

confidence: 99%

“…Microdialysis of Mel for 10 h͞day in the SCN, PVT, or NRE prevents gonadal maturation in photo-inhibited juvenile male Siberian hamsters housed in constant light (13). Constant release implants or timed injections of Mel in the vicinity of the SCN also cause gonadal inhibition in female white-footed mice (14,15). Because the SCN responds to lower concentrations of Mel (7.5 and 20 pg͞infusion) than the PVT or NRE (75 pg͞infusion), one can infer that this tissue is particularly sensitive to the hormone (13).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Refractoriness to melatonin occurs independently at multiple brain sites in Siberian hamsters

Freeman

Zucker

2001

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The mid-winter development of refractoriness to melatonin (Mel) triggers recrudescence of the atrophied reproductive apparatus of rodents. As a consequence, over-wintering animals become reproductively competent just before the onset of spring conditions favorable for breeding. The neural target tissues that cease to respond to winter Mel signals have not been identified. We now report that the suprachiasmatic nucleus of the hypothalamus, which contains the principal circadian clock, and the reuniens and paraventricular nuclei of the thalamus, each independently becomes refractory to melatonin. Small implants of Mel that were left in place for 40 wk and that act locally on these brain nuclei, induced testicular regression within 6 wk in male Siberian hamsters; 12 wk later Mel implants no longer suppressed reproduction and gonadal recrudescence ensued. Hamsters that were then given a systemic Mel infusion s.c. immediately initiated a second gonadal regression, implying that neurons at each site become refractory to Mel without compromising responsiveness of other Mel target tissues. Refractoriness occurs locally and independently at each neural target tissue, rather than in a separate ''refractoriness'' substrate. Restricted, target-specific actions of Mel are consistent with the independent regulation by day length of the several behavioral and physiological traits that vary seasonally in mammals.

show abstract

Section: Resultsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Refractoriness to melatonin occurs independently at multiple brain sites in Siberian hamsters

Freeman

Zucker

2001

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…In fact, the distribution of tissues that exhibit melatonin binding and receptor expression is highly species specific; the pars tuberalis (PT) of the pituitary gland is thought to be the only melatonin target tissue common to all mammals (Bittman 1993;Morgan et al 1994). Melatonin implants directed at various targets (including the anterior hypothalamus, SCN, nucleus reuniens, paraventricular nucleus of the thalamus or MBH) in sheep, Siberian hamsters or white-footed mice induce seasonal changes in various traits (Glass & Lynch 1982;Dowell & Lynch 1987;Badura & Goldman 1992;Lincoln & Maeda 1992;Malpaux et al 1998;. Although these studies provide evidence that melatonin can act at multiple structures to effect seasonal changes, they do not specify the precise role of the hormone at each site.…”

Section: On the Location Of Interval Timers And Circannual Clocksmentioning

confidence: 99%

Tracking the seasons: the internal calendars of vertebrates

Paul

Zucker

Schwartz

2007

Phil. Trans. R. Soc. B

175

152

View full text Add to dashboard Cite

Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.Keywords: seasonality; photoperiodism; circannual; interval timers While the Earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease.Genesis 8: 22, King James Version (1611) As the Earth makes its yearly orbit around the Sun, the planet's 23.58 axial tilt leads to the cyclical environmental changes that we call the seasons. Recurrent challenges to the survival of organisms and their offspring arise with the dawning of each new season, and animals have evolved seasonally induced changes in phenotype that adapt them to these predictable events. For example, in many temperate environments, winter is generally characterized by severe decreases in ambient temperature and food availability, leading to increased energetic demands at a time when resources are diminished. Because energy requirements of female mammals typically increase markedly during lactation (Bronson 1989) and newly weaned offspring are particularly vulnerable to environmental perturbations (Hill 1992), raising offspring during this time of year is often futile. Thus, many temperate species have evolved winter-specific behaviours and physiology to conserve energy (e.g. hibernation, a more insulative pelage, huddling) or provide for escape (e.g. migration). Many species also increase the chances of offspring survival by timing their mating behaviours so that parturition occurs during energetically favourable times of year.

show abstract

“…Melatonin may regulate progesterone synthesis by acting in one or a variety of organs such as the gonad (Abhilasha & Krishna 1999), pituitary (Martin & Saltler 1979), hypothalamus (Glass & Lynch 1981, Malpaux et al 2001, and CN (Glass & Lynch 1982). Most studies investigating the mechanism by which melatonin regulates reproduction have been focused in the hypothalamus and pituitary as target tissues (Malpaux et al 2001) with little attention directed to the role of melatonin in the ovary itself.…”

Section: Discussionmentioning

confidence: 99%

Melatonin regulates delayed embryonic development in the short-nosed fruit bat, Cynopterus sphinx

Banerjee

Meenakumari²,

Udin³

et al. 2009

Reproduction

View full text Add to dashboard Cite

The aim of the present study was to evaluate the seasonal variation in serum melatonin levels and their relationship to the changes in the serum progesterone level, ovarian steroidogenesis, and embryonic development during two successive pregnancies of Cynopterus sphinx. Circulating melatonin concentrations showed two peaks; one coincided with the period of low progesterone synthesis and delayed embryonic development, whereas the second peak coincided with regressing corpus luteum. This finding suggests that increased serum melatonin level during November-December may be responsible for delayed embryonic development by suppressing progesterone synthesis. The study showed increased melatonin receptors (MTNR1A and MTNR1B) in the corpus luteum and in the utero-embryonic unit during the period of delayed embryonic development. The in vitro study showed that a high dose of melatonin suppressed progesterone synthesis, whereas a lower dose of melatonin increased progesterone synthesis by the ovary. The effects of melatonin on ovarian steroidogenesis are mediated through changes in the expression of peripheral-type benzodiazepine receptor, P450 side chain cleavage enzyme, and LH receptor proteins. This study further showed a suppressive impact of melatonin on the progesterone receptor (PGR) in the utero-embryonic unit; this effect might contribute to delayed embryonic development in C. sphinx. The results of the present study thus suggest that a high circulating melatonin level has a dual contribution in retarding embryonic development in C. sphinx by impairing progesterone synthesis as well as by inhibiting progesterone action by reducing expression of PGR in the utero-embryonic unit. Reproduction (2009) 138 935-944

show abstract

Evidence for a Brain Site of Melatonin Action in the White-Footed Mouse, <i>Peromyscus leucopus</i>

Cited by 105 publications

References 29 publications

Refractoriness to melatonin occurs independently at multiple brain sites in Siberian hamsters

Refractoriness to melatonin occurs independently at multiple brain sites in Siberian hamsters

Tracking the seasons: the internal calendars of vertebrates

Melatonin regulates delayed embryonic development in the short-nosed fruit bat, Cynopterus sphinx

Contact Info

Product

Resources

About