Ontogenetic Diurnal Variation of Adrenal Responsiveness to ACTH and Stress in Rats

Leal, Ângela M. O.; Carvalho, Jordana; Moreira, Ayrton Custódio

doi:10.1159/000023428

Cited by 7 publications

(7 citation statements)

References 23 publications

(38 reference statements)

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“…From P14, as previously described by many groups, including us, there was a nocturnal increase of corticosterone concentrations. The well-known adult rat circadian rhythm acrophase was observed at ZT12 and nadir at ZT0 (11)(12)(13).…”

Section: Discussionmentioning

confidence: 96%

“…Moreover, the amplitude of the rhythms of the gene expression in SCN gradually increases during the postnatal development and achieves adult-like levels from P10 (10). The development of the HPA axis circadian rhythm was previously described in neonatal rats with predominant vespertine corticosterone plasma acrophase around postnatal day 16 (P16) (11)(12)(13). This pattern follows the gradual maturation of the SCN (14) Circadian rhythm has been detected in several peripheral fetal organs in rats even when the fetal SCN has not been completely functional (15,16).…”

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confidence: 90%

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Postnatal Ontogeny of the Circadian Expression of the Adrenal Clock Genes and Corticosterone Rhythm in Male Rats

et al. 2017

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The postnatal synchronization of the circadian variation of the adrenal clock genes in mammals remains unknown. We evaluated the postnatal ontogeny of daily variation of clock genes (Clock/Bmal1/Per1/Per2/Per3/Cry1/Cry2/Rorα/Rev-Erbα) and steroidogenesis-related genes (Star and Mc2r) in rat adrenals and its relationship with the emergence of plasma corticosterone rhythm using cosinor analysis. Plasma corticosterone circadian rhythm was detected from postnatal day (P)1, with morning acrophase, between zeitgeber time (ZT)0 and ZT2. From P14, there was a nocturnal acrophase of corticosterone at ZT20, which was associated with pups' eye opening. From P3 there was a circadian variation of the mRNA expression of Bmal1, Per2, Per3, and Cry1 genes with morning acrophase, whereas Rev-Erbα had nocturnal acrophase. From P14, Bmal1, Per2, Per3, and Cry1 acrophases advanced by approximately 10 hours, as compared with early neonatal days, becoming vespertine-nocturnal. In all postnatal ages, Per2 and Cry1 circadian profiles were synchronized in phase with the circadian rhythm of plasma corticosterone, whereas Bmal1 was in antiphase. An adult-like Star circadian rhythm profile was observed only from P21. In conclusion, our original data demonstrated a progressive postnatal maturation of the circadian variation of the adrenal clock genes in synchrony with the development of the corticosterone circadian rhythm in rats.

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Section: Discussionmentioning

confidence: 96%

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confidence: 90%

Postnatal Ontogeny of the Circadian Expression of the Adrenal Clock Genes and Corticosterone Rhythm in Male Rats

et al. 2017

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“…The differential effect of separation versus vehicle administration on adult GR expression is especially surprising given that the differences in neonatal plasma corticosterone concentrations are small for neonatal separation versus neonatal vehicle injections. However, our manipulations were performed during the stress hyporesponsive period (originally termed the stress non-responsive period) when the basal and stress response levels of corticosterone are markedly reduced or absent (De Kloet et al, 1988a, Walker, 1991, Leal et al, 1999, Zilz et al, 1999), and the differential increase in corticosterone in separated versus vehicle-injected pups was small but significant. These data suggest that corticosterone's regulation of GR expression during this period operates within a very narrow range, and thus even small variations in neonatal corticosterone may have profound effects on GR expression.…”

Section: 4 Discussionmentioning

confidence: 99%

Neonatal corticosterone administration impairs adult eyeblink conditioning and decreases glucocorticoid receptor expression in the cerebellar interpositus nucleus

2011

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Neonatal maternal separation alters adult learning and memory. Previously, we showed that neonatal separation impaired eyeblink conditioning in adult rats and increased glucocorticoid receptor (GR) expression in the cerebellar interpositus nucleus, a critical site of learning-related plasticity. Daily neonatal separation (1h/day on postnatal days 2-14) increases neonatal plasma corticosterone levels. Therefore, effects of separation on GR expression in the interpositus and consequently adult eyeblink conditioning may be mediated by neonatal increases in corticosterone. As a first step in exploring a potential role for corticosterone in the neonatal separation effects we observed, we assessed whether systemic daily (postnatal days 2-14) corticosterone injections mimic neonatal separation effects on adult eyeblink conditioning and GR expression in the interpositus. Control uninjected animals were compared to animals receiving either daily corticosterone injections or daily injections of an equal volume of vehicle. Plasma corticosterone values were measured in a separate group of control, neonatally separated, vehicle injected, or corticosterone injected pups. In adulthood, rats underwent surgery for implantation of recording and stimulating electrodes. After recovery from surgery, rats underwent 10 daily sessions of eyeblink conditioning. Then, brains were processed for GR immunohistochemistry and GR expression in the interpositus nucleus was assessed. Vehicle and corticosterone injections both produced much larger increases in neonatal plasma corticosterone than did daily maternal separation, with the largest increases occurring in the corticosterone-injected group. Neonatal corticosterone injections impaired adult eyeblink conditioning and decreased GR expression in the interpositus nucleus, while the effects of vehicle injections were intermediate. Thus, while neonatal injections and maternal separation both produce adult impairments in learning and memory, these manipulations produce opposite changes in GR expression. This suggests an inverted U-shaped relationship may exist between both neonatal corticosterone levels and adult GR expression in the interpositus nucleus, and adult GR expression in the interpositus and eyeblink conditioning.

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“…This indicates that the 3-week old rats do not respond to the stress of trauma and hemorrhage as in 6- and 10-week old rats, but are capable of secreting high basal levels of corticosterone. A likely reason for the lack of an increase in corticosterone following trauma and hemorrhage in 3-week old rats is the lesser sensitivity of the hypothalamic-pituitary-adrenal axis to stress in young rats (Leal et al 1999; Yoshimura et al 2003). The response of 6-week old rats was more modest than in 10-week old rats, but there was an increase of corticosterone in response to trauma and hemorrhage.…”

Section: Discussionmentioning

confidence: 99%

Age and tissue specific differences in the development of acute insulin resistance following injury

Zhai

Messina

2009

Journal of Endocrinology

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Injuries, hemorrhage, sepsis, burn, and critical illnesses all induce insulin resistance, and insulin resistance is strongly associated with advancing age. However, the effect of age on injury induced insulin resistance is not well studied. We performed surgical trauma in male rats of three different ages (3-, 6-, and 10-weeks old). Rats were either hemorrhaged to a mean arterial pressure of 35-40 mmHg and subsequently maintained at that pressure for up to 90 min, or maintained without hemorrhage as controls. Results indicate that insulininduced intracellular signaling was diminished in liver and skeletal muscle of 6-and 10-week old rats following trauma and hemorrhage. In even younger rats, immediately postweaning (w3 weeks of age), insulin signaling was lost in liver, but not in skeletal muscle. Glucocorticoids can play a role in the chronic development of insulin resistance. Our results demonstrate that corticosterone levels were increased in 6-and 10-week old animals following hemorrhage, but little change was measured in 3-week old animals. Blockade of glucocorticoid synthesis prevented the development of insulin resistance in skeletal muscle, but not in liver of 6-and 10-week old rats. Moreover, skeletal muscle glucocorticoid receptor levels increased dramatically between 3 and 6 weeks of age. These results indicate that trauma and hemorrhage-induced hepatic insulin resistance occurs at all ages tested. However, there is no development of insulin resistance following trauma and hemorrhage in skeletal muscle of post-weaning rats. In skeletal muscle of 6-and 10-week old rats, inhibition of glucocorticoid levels prevents the development of insulin resistance.

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Ontogenetic Diurnal Variation of Adrenal Responsiveness to ACTH and Stress in Rats

Cited by 7 publications

References 23 publications

Postnatal Ontogeny of the Circadian Expression of the Adrenal Clock Genes and Corticosterone Rhythm in Male Rats

Postnatal Ontogeny of the Circadian Expression of the Adrenal Clock Genes and Corticosterone Rhythm in Male Rats

Neonatal corticosterone administration impairs adult eyeblink conditioning and decreases glucocorticoid receptor expression in the cerebellar interpositus nucleus

Age and tissue specific differences in the development of acute insulin resistance following injury

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