Lesions of the Suprachiasmatic Nuclei and the Serotonin-Dependent Phasic Release of Luteinizing Hormone in the Rat: Effects on Drinking Rhythmicity and on the Consequences of Preoptic Area Stimulation

Coen, Clive W.; Mackinnon, P. C. B.

doi:10.1677/joe.0.0840231

Cited by 39 publications

(16 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This finding was confirmed in another report that also found a disruption of the ACTH rhythm by SCN lesions [73]. It was reported that lesions of the SCN of ovariectomized female rats abolished the estrogen-induced LH surge as well as disrupting the rhythmicity of drinking behavior [74]. In squirrel monkeys, SCN lesions resulted in the abolition of circadian drinking behavior [75]; however, this process took several weeks, suggesting the existence of other circadian components outside the SCN in this primate.…”

Section: Evidence For the Scn As The Circadian Pacemakersupporting

confidence: 80%

“…The literature on TSH release both in young and elderly humans is somewhat limited and controversial, with reports of increased [15] or unchanged [16] levels during aging. In the most convincing study comparing young (20-27 year) and elderly (67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84) year) men in a circadian context, it was found that in young humans, TSH release has a circadian rhythmicity, with increases observed beginning at night (#22:00 h), approximately 3-4 h before sleep onset, levels remaining elevated at night and then decreasing during the morning ( fig. 2) [17].…”

Section: Thyroid-stimulating Hormonementioning

confidence: 99%

See 1 more Smart Citation

Circadian Rhythms during Aging

Gore¹

1998

Interdisciplinary Topics in Gerontology

View full text Add to dashboard Cite

Section: Evidence For the Scn As The Circadian Pacemakersupporting

confidence: 80%

Section: Thyroid-stimulating Hormonementioning

confidence: 99%

Circadian Rhythms during Aging

Gore¹

1998

Interdisciplinary Topics in Gerontology

View full text Add to dashboard Cite

“…The SCN is the center for the major 'biological clock', and its integrity is critical for maintenance of regular estrous cyclicity [36] as well as circa dian rhythmicity of other physiological functions [37,38[. In males, diurnal rhythms in cAMP concentrations occur in SCN which can be entrained to the photoperiod and are independent of corticosterone rhythm [39].…”

Section: Discussionmentioning

confidence: 99%

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Weiland

Wise²

1989

Neuroendocrinology

View full text Add to dashboard Cite

The effect of norepinephrine on LH is complex: the ovarian steroidal milieu appears to determine whether norepinephrine stimulates or inhibits LH secretion. It has been proposed that steroids allow norepinephrine to have opposite effects on LH by altering the relative concentrations of α₁-(stimulatory) and β-(inhibitory) adrenergic receptors in the hypothalamus. Thus, many investigators have argued that estradiol may permit norepinephrine to stimulate LH release by increasing the density of α₁- and decreasing the density of β-adrenergic receptors in one or more key hypothalamic regions. To test this hypothesis specifically, we measured the density of β₁- and β₂-adrenergic receptor densities in proestrous, ovariectomized, and ovariectomized estradiol-treated rats at various times of day to determine (1) whether the densities of β-receptors exhibit diurnal rhythmicity, (2) whether β-receptors decrease during the time of increased LH secretion and/or (3) how steroidal milieu influences the density and/or the rhythm of receptor densities. The densities of β₁- and β₂-receptors exhibit a diurnal rhythm in some brain areas. These rhythms are detectable only in proestrous and ovariectomized rats and only in selected brain regions. Estrogen treatment has opposing effects in different brain regions. It suppresses the rhythm of β₁-receptor concentrations in ovariectomized rats and also suppresses the average density of receptors in the suprachiasmatic nucleus and pineal gland. In contrast, estrogen increases the density of β₁-receptors in the medial preoptic nucleus. In summary, the results of this study demonstrate that the diurnal rhythm in β-receptors and the effect of estradiol correlate with previously reported changes in receptor-mediated functions. In addition, they reveal the complex interactions of time of day and steroidal milieu on the density of β₁- and β₂-receptors in various brain regions. Finally, the data strongly suggest that decreases in the densities of β-receptors cannot explain the timing of the proestrous or estradiol-induced LH surge or the ability of norepinephrine to inhibit LH release in ovariectomized rats or stimulate LH release in steroid-treated rats.

show abstract

“…If these signals are delayed or suppressed sufficiently, preovulatory gonadotropin release is delayed by an entire day and occurs at the proper time 24 hr later. The suprachiasmatic nucleus (SCN) is often called the "biological clock" because its integrity is critical to the maintenance of biological functions that have a circadian basis, including cyclic reproductive function (8)(9)(10)(11)(12). Previous studies demonstrated that the diurnal rhythms of norepinephrine and serotonin turnover rates, which accompany cyclic luteinizing hormone (LH) release, are altered in the SCN of middle-aged rats when they enter the transition to age-related estrous acyclicity (13)(14)(15).…”

Section: Introductionmentioning

confidence: 99%

Aging alters the circadian rhythm of glucose utilization in the suprachiasmatic nucleus.

Wise

Weiland

et al. 1988

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

View full text Add to dashboard Cite

We examined the possibility that alterations in the timing of cyclic luteinizing hormone (LH) release during the middle age transition to infertility reflect differences in the circadian pattern of neural function in pacemaker areas of the hypothalamus, particularly the suprachiasmatic nucleus. We measured local cerebral glucose utilization (LCGU) because this parameter is an index of local brain function. We assessed LCGU in several brain areas of young and middle-aged ovariectomized estradiol-treated rats since LH surges are altered when rats are middle-aged. This alteration is correlated with changes in the diurnal pattern of neurotransmitter turnover in several hypothalamic areas that regulate cyclic LH release. The data demonstrate a circadian rhythm in glucose utilization in the dorsal and ventral suprachiasmatic nucleus. In young rats, LCGU increases within 1 hr of lights-on, increases further just prior to the initiation of the LH surge, and decreases within 1 hr oflights-off. In contrast, middle-aged rats show a more gradual increase in LCGU after lights-on, with no further increase prior to the LH surge, and a premature decrease during the afternoon and evening. The data suggest that changes in the circadian pattern of LCGU may be related to the alteration in timing and amplitude of estradiol-induced LH surges in middle-aged rats. Changes in the integrity of the biological clock or in the ability of the biological clock to entrain other neurochemical events may underlie the onset of altered cyclic reproductive function and the transition to irregular estrous cyclicity.The female reproductive system provides a unique model system to investigate mechanisms regulating endocrinedependent aging processes because changes that lead ultimately to infertility and the disappearance of reproductive cycles occur relatively early during adulthood. Thus, one can examine the regulation of aging processes in the virtual absence of age-related pathologies. The reproductive system of the aged female is characterized by the absence of both cyclic gonadotropin release and cyclic ovarian function. The period of total acyclicity and infertility follows a transitional phase during which ovulations occur at increasingly irregular intervals, the probability that a given cycle will be ovulatory is reduced, and the pattern of preovulatory gonadotropin surges and steroid hormone release is altered. Hypothalamic, pituitary, and ovarian functions are altered during the middleage transitional phase (1-4); however, the relative contribution of each to the transition to reproductive acyclicity is not well understood. The present study tested the hypothesis that a loss in precision of the circadian rhythm of hypothalamic function occurs during middle age, disrupting cyclic reproductive function.Reproductive cyclicity has a circadian basis and depends on the integrity of a neural pacemaker (5-7). Everett et al. (5) proposed that, in rodents, the timing and regularity of preovulatory gonadotropin surges are governed by diurnal ne...

show abstract

Lesions of the Suprachiasmatic Nuclei and the Serotonin-Dependent Phasic Release of Luteinizing Hormone in the Rat: Effects on Drinking Rhythmicity and on the Consequences of Preoptic Area Stimulation

Cited by 39 publications

References 4 publications

Circadian Rhythms during Aging

Circadian Rhythms during Aging

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Aging alters the circadian rhythm of glucose utilization in the suprachiasmatic nucleus.

Contact Info

Product

Resources

About