Locus coeruleus lesions decrease norepinephrine input into the medial preoptic area and medial basal hypothalamus and block the LH, FSH and prolactin preovulatory surge

Anselmo-Franci, J; Franci, Celso Rodrigues; Krulich, L.; Antunes‐Rodrigues, José; McCann, Samuel M.

doi:10.1016/s0006-8993(97)00613-6

Cited by 76 publications

(67 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Locus coeruleus (LC) is the major noradrenergic nucleus and sends projections to the entire CNS, including areas involved in GnRH synthesis and secretion (Swanson & Hartman 1975, Foote et al 1983, Wright & Jennes 1993. Data from our laboratory have demonstrated that electrolytic lesion of LC decreases noradrenaline content in medial POA and medial basal hypothalamus and blocks the preovulatory gonadotropin surges observed during proestrus as well as LH pulses (Anselmo-Franci et al 1999) and the steroidinduced surge in ovariectomized rats by decreasing GnRH release (Franci & Antunes-Rodrigues 1985, Anselmo-Franci et al 1997, 1999, Helena et al 2002, Martins-Afferri et al 2003 . Also, an increased number of FOS-immunoreactive (FOS-ir) neurons was observed in LC simultaneously with the preovulatory gonadotropin surges (Martins-Afferri et al 2003).…”

Section: Introductionmentioning

confidence: 95%

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

Helena¹,

Poletini²,

Sanvitto³

et al. 2006

Journal of Endocrinology

View full text Add to dashboard Cite

We have previously shown that the locus coeruleus (LC) is essential for triggering surges of LH. Since LC neurons are responsive to estradiol, which induces progesterone receptor (PR) expression, this study aimed to investigate whether LC neurons express the -estradiol receptor ( ER) and PR as well as comparing such responses to that observed in the preoptic area (POA). Female rats were perfused at 10, 14 and 16 h on each day of the estrous cycle, and a blood sample was collected for estradiol, progesterone and LH measurements. ER-and PR immunoreactive (ir) neurons were detected in POA and LC by immunocytochemistry (ICC). Higher plasma estradiol levels were observed on the day of proestrus, when a smaller number of ER-ir POA neurons were detected. An increase in the number of ER-ir neurons were observed at 16 h of proestrus and estrus. The number of PR-ir neurons increased in POA only at 16 h of proestrus, and remained unchanged during all other days and times. The profile of ER-ir and PR-ir neurons in LC changed over the estrous cycle, with a lower expression on metestrus morning and reaching a peak on diestrus afternoon before declining on the day of proestrus. However, on estrus afternoon, ER-ir neurons increased, while PR-ir neurons decreased which may be related to the prolactin surge of estrus. These data show that LC neurons express ER and PR and seem to be more sensitive to variations in estradiol than POA. Also, the fluctuation in ER and PR observed for LC neurons seems to accompany the hormonal events that occur during the estrous cycle. This profile of ER and PR expression might be related to the ability of estradiol and progesterone in regulating the activity of LC neurons, which could be associated to the control mechanisms of LH and prolactin release.

show abstract

Section: Introductionmentioning

confidence: 95%

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

Helena¹,

Poletini²,

Sanvitto³

et al. 2006

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…To assess the preovulatory LH surge in cycling rats, a right atrial catheter was inserted (20) on the morning of proestrous (before 1200 h) under tribromoethanol anesthesia (21). Pulsatile LH release was assessed in female and male rats castrated for 4 weeks.…”

Section: Evaluation Of Transgene Expression By In Situ Hybridizationmentioning

confidence: 99%

Phosphodiesterase expression targeted to gonadotropin-releasing hormone neurons inhibits luteinizing hormone pulses in transgenic rats

Paruthiyil

Majdoubi

Conti

et al. 2002

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

View full text Add to dashboard Cite

Experiments in the GT1 gonadotropin-releasing hormone (GnRH) cell line have shown that the cAMP signaling pathway plays a central role in regulating the excitability of the cells. Lowering cAMP levels by expressing the constitutively active cAMP-specific phosphodiesterase PDE4D1 in GT1 cells inhibited spontaneous Ca 2؉ oscillations and intrinsic pulsatile GnRH secretion. To address the role of cAMP levels in endogenous GnRH neurons, we genetically targeted expression of PDE4D1 (P) to GnRH neurons in transgenic rats (R) by using the GnRH gene promoter͞enhancer regions (G). Three lines of transgenic rats, GPR-2, -4, and -5, were established. In situ hybridization and RT-PCR studies demonstrated that transgene expression was specifically targeted to GnRH neurons. Decreased fertility was observed in female but not in male rats from all three lines. The mean luteinizing hormone (LH) levels in ovariectomized rats were significantly reduced in the GPR-4 and -5 lines but not in the GPR-2 line. In castrated male and female GPR-4 rats, the LH pulse frequency was dramatically reduced. Six of twelve GPR-4 females studied did not ovulate and had polycystic ovaries. The remaining six females ovulated, but the magnitude of the preovulatory LH surge was inhibited by 63%. These findings support the hypothesis that cAMP signaling may play a central role in regulating excitability of GnRH neurons in vivo. The GPR-4 line of transgenic rats provides a genetic model for the understanding of the role of pulsatile gonadotropin release in follicular development.T he pulsatile release of gonadotropin-releasing hormone (GnRH) underlies reproductive function in male and female mammals. Understanding the molecular mechanisms regulating pulsatile GnRH secretion has been hampered by the low number of GnRH neurons and their scattered localization throughout the preoptic area in rodents. Further complicating the understanding of these questions is the complexity of the neural connectivity of GnRH neurons. The development of the highly differentiated GT1 GnRH neuronal cell lines (1) and the demonstration that pulsatile release was an intrinsic property of the cells provided a model to study molecular events underlying pulsatile GnRH release (2-4). However, one is always faced with the problem of translating findings from an immortalized cell line to the physiological setting. We have attempted to bridge observations made in GT1 cells regarding signaling events regulating GnRH pulsatility to the physiological setting by developing a transgenic rat model. We used an established genetic approach to alter the activity of a signaling pathway that could be used in parallel experiments in GT1 cells and transgenic rats. Transgenic rats, unlike transgenic mice, permit the reliable analysis of pulsatile luteinizing hormone (LH) release that closely mimics pulsatile GnRH release in castrated animals (5).The secretion of GnRH in GT1 neurons is stimulated by elevations in cAMP levels (6-8). The stimulation of GnRH secretion by elevated cAMP levels appears to...

show abstract

“…Moreover, estrogen level during the estrous cycle is associated with the expression of FOS protein in the A1 nucleus (15). Locus coeruleus projects to the preoptic area and to the suprachiasmatic nucleus, which are involved in the regulation of cyclic secretion of hormones in the anterior pituitary (16,17). Luteinizing hormone and prolactin surge (16), as well as secretion of corticotrophin releasing hormone (18) are dependent on noradrenergic inputs.…”

mentioning

confidence: 99%

“…Locus coeruleus projects to the preoptic area and to the suprachiasmatic nucleus, which are involved in the regulation of cyclic secretion of hormones in the anterior pituitary (16,17). Luteinizing hormone and prolactin surge (16), as well as secretion of corticotrophin releasing hormone (18) are dependent on noradrenergic inputs. Electrolytic lesions of the locus coeruleus on the morning of proestrus decrease the content of norepinephrine in the medial preoptic area and medial basal hypothalamus and block the pre-ovulatory surge of gonadotrophins and therefore ovulation (16).…”

mentioning

confidence: 99%

Neonatal handling induces anovulatory estrous cycles in rats

Gomes

Frantz

Sanvitto

et al. 1999

Braz J Med Biol Res

View full text Add to dashboard Cite

Since previous work has shown that stimulation early in life decreases sexual receptiveness as measured by the female lordosis quotient, we suggested that neonatal handling could affect the function of the hypothalamus-pituitary-gonadal axis. The effects of neonatal handling on the estrous cycle and ovulation were analyzed in adult rats. Two groups of animals were studied: intact (no manipulation, N = 10) and handled (N = 11). Pups were either handled daily for 1 min during the first 10 days of life or left undisturbed. At the age of 90 days, a vaginal smear was collected daily at 9:00 a.m. and analyzed for 29 days; at 9:00 a.m. on the day of estrus, animals were anesthetized with thiopental (40 mg/kg, ip), the ovaries were removed and the oviduct was dissected and squashed between 2 glass slides. The number of oocytes of both oviductal ampullae was counted under the microscope. The average numbers for each phase of the cycle (diestrus I, diestrus II, proestrus and estrus) during the period analyzed were compared between the two groups. There were no significant differences between intact and handled females during any of the phases. However, the number of handled females that showed anovulatory cycles (8 out of 11) was significantly higher than in the intact group (none out of 10). Neonatal stimulation may affect not only the hypothalamus-pituitary-adrenal axis, as previously demonstrated, but also the hypothalamus-pituitary-gonadal axis in female rats.

show abstract

Locus coeruleus lesions decrease norepinephrine input into the medial preoptic area and medial basal hypothalamus and block the LH, FSH and prolactin preovulatory surge

Cited by 76 publications

References 28 publications

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

Phosphodiesterase expression targeted to gonadotropin-releasing hormone neurons inhibits luteinizing hormone pulses in transgenic rats

Neonatal handling induces anovulatory estrous cycles in rats

Contact Info

Product

Resources

About