Circadian Rhythms during Aging

Gore, Andrea C.

doi:10.1159/000061417

Cited by 2 publications

(3 citation statements)

References 163 publications

(251 reference statements)

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“…A hallmark of aging is changes in concentrations of the release patterns of peripheral hormones (Gore, 1998). Our results add to the literature of effects of castration and E2 treatment during aging in male rats.…”

Section: Discussionmentioning

confidence: 99%

Aging and estradiol effects on gene expression in the medial preoptic area, bed nucleus of the stria terminalis, and posterodorsal medial amygdala of male rats

Nutsch

Bell

Will

et al. 2017

Molecular and Cellular Endocrinology

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Studies on the role of hormones in male reproductive aging have traditionally focused on testosterone, but estradiol also plays important roles in the control of masculine physiology and behavior. Our goal was to examine the effects of E2 on the expression of genes selected for E2-sensitivity, involvement in behavioral neuroendocrine functions, and impairments with aging. Mature adult (MAT, 5 mo.) and aged (AG, 18 mo.) Sprague-Dawley male rats were castrated, implanted with either vehicle or estradiol (E2) subcutaneous capsules, and euthanized one month later. Bilateral punches were taken from the bed nucleus of the stria terminalis (BnST), posterodorsal medial amygdala (MePD) and the preoptic area (POA). RNA was extracted, and expression of 48 genes analyzed by qPCR using Taqman low-density arrays. Results showed that effects of age and E2 were age- and region-specific. In the POA, 5 genes were increased with E2 compared to vehicle, and there were no age effects. By contrast the BnST showed primarily age-related changes, with 6 genes decreasing with age. The MePD had 5 genes that were higher in aged than mature males, and 17 genes with significant interactions between age and E2. Gene families identified in the MePD included nuclear hormone receptors, neurotransmitters and neuropeptides and their receptors. Ten serum hormones were assayed in these same males, with results revealing both age- and E2-effects, in several cases quite profound. These results support the idea that the male brain continues to be highly sensitive to estradiol even with aging, but the nature of the response can be substantially different in mature and aging animals.

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Section: Discussionmentioning

confidence: 99%

Aging and estradiol effects on gene expression in the medial preoptic area, bed nucleus of the stria terminalis, and posterodorsal medial amygdala of male rats

Nutsch

Bell

Will

et al. 2017

Molecular and Cellular Endocrinology

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“…Presumably, the signal regulating the estrous cycle is sexually dimorphic, thereby lending further support for VIP regulation of estrus. Furthermore, antisense oligonucleotides directed against VIP lead to a delayed and attenuated LH surge (Harney et al, 1996), reminiscent of that seen in middle-aged rats (Gore, 1998). Sex differences also exist in the pattern of projections from the SCN (Horvath et al, 1998;Van der Beek et al, 1997a,b).…”

Section: Neural Scn Output and Estrus Regulationmentioning

confidence: 96%

“…The present review highlights the current understanding of circadian system regulation of endocrine rhythms via multiple means of modulation and proposes a novel mechanism of hierarchical control beginning with the master brain clock. For a complete description of daily hormone secretion patterns, the reader is referred to the following reviews (Gore, 1998;Hastings, 1991;Kriegsfeld et al, 2002a;Turek and Van Cauter, 1994).…”

Section: Circadian Control Of Endocrine Secretionsmentioning

confidence: 99%

The regulation of neuroendocrine function: Timing is everything

Kriegsfeld

Silver

2006

Hormones and Behavior

131

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Hormone secretion is highly organized temporally, achieving optimal biological functioning and health. The master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus coordinates the timing of circadian rhythms, including daily control of hormone secretion. In the brain, the SCN drives hormone secretion. In some instances, SCN neurons make direct synaptic connections with neurosecretory neurons. In other instances, SCN signals set the phase of "clock genes" that regulate circadian function at the cellular level within neurosecretory cells. The protein products of these clock genes can also exert direct transcriptional control over neuroendocrine releasing factors. Clock genes and proteins are also expressed in peripheral endocrine organs providing additional modes of temporal control. Finally, the SCN signals endocrine glands via the autonomic nervous system, allowing for rapid regulation via multisynaptic pathways. Thus, the circadian system achieves temporal regulation of endocrine function by a combination of genetic, cellular, and neural regulatory mechanisms to ensure that each response occurs in its correct temporal niche. The availability of tools to assess the phase of molecular/cellular clocks and of powerful tract tracing methods to assess connections between "clock cells" and their targets provides an opportunity to examine circadian-controlled aspects of neurosecretion, in the search for general principles by which the endocrine system is organized. KeywordsCircadian; Diurnal; Endocrinel; Neurosecretion; Clock genes; Suprachiasmatic Circadian aspects of reproductionThe importance of circadian (about a day) timing in hormone production/secretion has been known since the 1950s when Everett and Sawyer determined that a stimulatory signal occurring during a narrow temporal window on the afternoon of proestrus is necessary for induction of ovulation later that night (Everett and Sawyer, 1950). Such close temporal organization is important for successful reproduction, as numerous hormone-dependent behavioral and physiological processes must be coordinated. If optimal temporal relationships are disrupted, pronounced deficits in fertility can result. For example, ovulation, behavioral estrus, fertilization, and pregnancy maintenance require a specific

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Circadian Rhythms during Aging

Cited by 2 publications

References 163 publications

Aging and estradiol effects on gene expression in the medial preoptic area, bed nucleus of the stria terminalis, and posterodorsal medial amygdala of male rats

Aging and estradiol effects on gene expression in the medial preoptic area, bed nucleus of the stria terminalis, and posterodorsal medial amygdala of male rats

The regulation of neuroendocrine function: Timing is everything

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