Effects of Lesions in Various Structures of the Suprachiasmatic-Preoptic Region on LH Regulation and Sexual Behavior in Female Rats

Gray, Gary D.; Söderstein, P; Tallentire, D; Davidson, Julian M.

doi:10.1159/000122739

Cited by 145 publications

(52 citation statements)

References 4 publications

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“…Recent studies have further localized the lesion effect in the suprachiasmatic region to the SCN (BrownGrant and Raisman, 1977;Clemens et al, 1976;Gray et al, 1978;Samson and McCann, 1980;Wiegand et al, 1978Wiegand et al, , 1980Wiegand and Terasawa, 1982), the OVLT region (Samson and McCann, 1979) and the MPN (Wiegand et al, 1978Terasawa et al, 1980;Wiegand and Terasawa, 1982). These results were generally attributed to the presence of a trigger in the preoptic region which stimulates release of LHRH from peptidergic neurons in the medial basal hypothalamus (MBH).…”

Section: Discussionmentioning

confidence: 99%

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

Terasawa¹,

Davis²

1983

Endocrinol Japon

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Previously we have found that small lesions confined to the medial preoptic nucleus (MPN) or the suprachiasmatic nucleus (SCN) blocked the cyclic release of gonadotropins in the female rat, inducing a persistent estrous state. Since the MPN is located just caudal to the organum vasculosum of the lamina terminalis (OVLT) where LHRH cell bodies are most concentrated, we applied an immunocytochemical technique to examine the possibility that the lesions had simply disrupted LHRH neurons or fibers.Using a new anti-LHRH provided by Dr. V. D. Ramirez, we found that the distribution pattern of immunoreactive LHRH cell bodies and fibers was similar to that previously reported, although the staining was more intense and extensive with low background.There was no concentration of LHRH cell bodies and fibers in the MPN or SCN and, in fact, these nuclei generally showed a lower density of stained elements than did sorrounding tissue. In persistent estrous animals with lesions confined to the MPN there was no detectable reduction of staind fibers in the median eminence.These results, along with the results of other workers, suggest that persistent estrus following lesions of the MPN or SCN is not due to reduction of LHRH neurons or fibers. Rather, they support the hypothesis that these nuclei are critical for triggering the ovulatory release of LHRH.

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Section: Discussionmentioning

confidence: 99%

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

Terasawa¹,

Davis²

1983

Endocrinol Japon

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“…Thus, maternal condition, health and intact rhythmicity all affect the reproductive success. Disruption of the circadian signal caused by SCN lesions interrupts cyclic ovulation (Gray et al 1978). Specific changes in the molecular function in the SCN, e.g.…”

Section: Introductionmentioning

confidence: 99%

Low reproductive success in Per1 and Per2 mutant mouse females due to accelerated ageing?

Pilorz¹,

Steinlechner²

2008

Reproduction

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Recent studies on mice with mutations in the Clock gene have shown that this mutation disrupts oestrus cyclicity and interferes with successful pregnancy. In order to determine whether two other molecular components of the main clock, namely the period genes, Per1 and Per2, have an effect on the length of the oestrous cycle and the reproductive success, we used Per1-and Per2-deficient females. We show that although fecundity of young adult Per mutant females does not differ from that of wild-type females, middle-aged Per mutant mice are characterised by lower reproductive success than the control group. This may be a consequence of irregularity and acyclicity of the oestrous cycle of the middle-aged mutants. Besides, we demonstrate that Per mutant females have significantly more embryonal implantations in the uterus than successfully delivered offspring. The reproductive deficits of the middle-aged Per mutant females are comparable with those seen in aged wild-type mice. This suggests that Per1 and Per2 mutations cause an advanced ageing.Reproduction (2008) 135 559-568

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“…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).…”

mentioning

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.

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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...

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Effects of Lesions in Various Structures of the Suprachiasmatic-Preoptic Region on LH Regulation and Sexual Behavior in Female Rats

Cited by 145 publications

References 4 publications

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

Low reproductive success in Per1 and Per2 mutant mouse females due to accelerated ageing?

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

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