Age-Related Changes in Central Nervous System Beta-Endorphin and ACTH

Gambert, Steven; Garthwaite, Thomas L.; Pontzer, Carol H.; Hagen, Thad C.

doi:10.1159/000123083

Cited by 129 publications

(29 citation statements)

References 13 publications

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“…Consistently, studies carried out in the rat have dem onstrated age-induced changes in [1-endorphin content in the hypothalamus, in the pituitary and plasma [34][35][36], as well as in p-receptor number and in the molecular form of (1-and y-endorphins in the hypothalamus of aged rats [37,38], Accordingly, the present and some other studies have shown that naloxone is unable to modify plasma LH levels in aged male rats [21] and in elderly humans of ei ther sex [39,40].…”

Section: Discussionsupporting

confidence: 57%

Melatonin Treatment Delays Reproductive Aging of Female Rat via the Opiatergic System

et al. 1992

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In female rat age-related reproductive decline is accompanied by progressive impairment of the neuroendocrine mechanisms that regulate LH secretion. The biosynthetic activity of the pineal gland is markedly depressed and the nocturnal secretion of melatonin decreases significantly. The aim of the present study was to evaluate whether the nocturnal administration of melatonin via the drinking water (0.4 µg/ml) throughout the course of aging from 14 to 24 months of age could (1) influence the age-related changes that occur in basal serum levels of LH and in the LH response to GnRH or to naloxone stimulation at 16, 18 and 20 months of age, and (2) delay the onset of the postreproductive constant estrous-anovulatory state as evaluated by the daily recording of vaginal smears and by occurrence of polyfollicular ovaries at 24 months of age. Our results demonstrate that melatonin replacement delays the increase in LH serum levels and the decrease in LH response to GnRH that occur in 18-month-old control animals. Furthermore, they show that melatonin treatment prevents the loss of LH response to naloxone manifested in control rats between 16 and 20 months of age. Melatonin also appears to prevent the progressive increase in the monthly occurrence of estrus phases as well as to decrease the number of rats with polyfollicular ovaries at 24 months of age in comparison to control animals. These results suggest that the age-related decrease in circulating melatonin during the night may contribute to the reproductive decline of aging, and that this effect may involve the central opioid system.

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Section: Discussionsupporting

confidence: 57%

Melatonin Treatment Delays Reproductive Aging of Female Rat via the Opiatergic System

et al. 1992

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“…The anterior pituitary ACTH content does not change with age [24], We were unable to find studies reporting the in vitro activity of the aged pituitary. However, a different time course of plasma immunoreactive ACTH response to in vivo ovine CRH (oCRH) administration has been reported between young and old rats [25].…”

Section: Discussionmentioning

confidence: 88%

Age-Related Changes in Hypothalamo-Pituitary-Adrenocortical Axis Activity in the Rat

Scaccianoce¹,

Sciullo²,

Angelucci³

1990

Neuroendocrinology

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In the aged rat, the activity of the hypothalamo-pituitary-adrenocortical (HPA) axis was found to be increased. In fact, the plasma corticosterone concentrations in the aged (25 months) Sprague-Dawley rat were higher than in the young (3 months) Sprague-Dawley rat. To determine which component of the HPA axis principally contributes to this hyperactivity, an in vitro approach was applied. Neither the adrenal nor the pituitary revealed any age-induced modification in their basal or hormone-stimulated in vitro activity. Moreover, the ability of corticosterone to inhibit the in vitro stimulated pituitary adrenocorticotropic hormone release was preserved in aged rats. On the contrary, the in vitro hypothalamic activity was altered in aged rats. The basal and stimulated release of bioactive corticotropin-releasing factor were increased in aged rats. The results obtained in this study indicate that the hypercorticosteronemia of the aged Sprague-Dawley rat is associated with hypothalamic hyperactivity and with normal in vitro activity and reactivity of the adrenal and pituitary.

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“…With few exceptions (20,21), prior studies examining peptide content in the aged brain describe either no change or decreases (22)(23)(24)(25)(26)(27). Elevations in peptide content and/or peptide gene expression can be induced experimentally by manipulations that alter neural activity.…”

Section: Discussionmentioning

confidence: 99%

Elevated dynorphin in the hippocampal formation of aged rats: relation to cognitive impairment on a spatial learning task.

Jiang

Owyang

Hong

et al. 1989

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

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Radioimmunoassayrevealedincreaseddynorphin A(1-8)-like immunoreactivity [dynA(1-8)LIJ in the aged rat brain. Among a number of brain regions examined, an age-related dynA(l-8)LI elevation was found only in the hippocampal formation and frontal cortex. Moreover, the increase in dynA(l-8)LI in the aged hippocampus was associated with a decline in spatial learning ability: dynA(l-8)LI distinguished aged rats that were behaviorally impaired from aged cohorts that learned the spatial task as rpidly as younger animals. Northern blot hybridization US a 2P-labeled complementary RNA probe encoding rat prodyporphin indicated that the abundance of prodynorphin mRNA was also significantly icreased in the hippocampal formation ofaged rats with identified spatial learning impairments.The neurobiological status of the aging hippocampal formation includes a loss of afferent input (1, 2), a modest decline in neuron number (3-5), a diminished complement of synaptic connections (6,7), and decreases in some measures that reflect neurochemical function (8,9). A more severe deterioration in this system is evident in the brains of patients with Alzheimer disease (10,11). The effects of aging and agerelated pathology on the hippocampal formation are likely to contribute to the emergence of mild cognitive deficits in normal aging and the progressive cognitive decline associated with Alzheimer dementia.In contrast to the attrition reported for many parameters in the aged hippocampus, this study describes a significant elevation of a neuropeptide system that, within the hippocampal formation of young adult rats, is largely restricted to the dentate granule cells and their mossy fiber projections to CA3 (12). We report that dynorphin A(1-8)-like immunoreactivity [dynA(1-8)LI] and prodynorphin mRNA are increased in the aged hippocampal formation relative to young adults. This neurobiological change was also examined in relation to the performance of aged rats on a spatial learning task that is sensitive to hippocampal dysfunction (13 Rats were trained to locate the camouflaged escape platform, which remained in the same position in the maze throughout training. Animals received three trials per day for 12 consecutive days, using a 60-sec intertrial interval. On each training trial, an animal was released in the maze from one of four equally spaced starting positions around the perimeter of the tank. The starting position varied from trial to trial, thus precluding the effective use of a response strategy (e.g., always turning left from the starting location to locate the escape platform). If an animal did not locate the escape platform within 120 sec on any trial, the experimenter placed the animal on the platform, where it remained for 30 sec. Every sixth trial consisted of a 30-sec probe trial to assess the development of a spatial bias in the maze. During these trials, animals swam with the platform removed from the pool. A criterion performance was achieved on a probe trial when an animal crossed the precise position of the esca...

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Age-Related Changes in Central Nervous System Beta-Endorphin and ACTH

Cited by 129 publications

References 13 publications

Melatonin Treatment Delays Reproductive Aging of Female Rat via the Opiatergic System

Melatonin Treatment Delays Reproductive Aging of Female Rat via the Opiatergic System

Age-Related Changes in Hypothalamo-Pituitary-Adrenocortical Axis Activity in the Rat

Elevated dynorphin in the hippocampal formation of aged rats: relation to cognitive impairment on a spatial learning task.

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