Age-Related Change in the Twenty-Four Hour Spontaneous Secretion of Growth Hormone

Finkelstein, Jordan W.; Roffwarg, Howard P.; Boyar, Robert M.; Kream, Jacob; Hellman, Louis M.

doi:10.1210/jcem-35-5-665

Cited by 660 publications

(237 citation statements)

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“…Although it is generally accepted that basal GH secretion decreases in humans and animals with increasing age (Borst et al, 1994;De Genarro Colonna et al, 1994;Finkelstein et al, 1972;Sonntag et al, 1980;Wilshire et al, 1995;Zadik et al, 1985), the basal plasma GH concentration in our study was not significantly different in the young and the old dogs. For identifying age-related differences in GH secretion, determination of the pulsatile secretion pattern of GH is much more sensitive.…”

Section: Ghrp-6contrasting

confidence: 72%

“…Both basal and stimulated GH secretion and circulating insulin-like growth factor-I (IGF-1) concentrations decline with age in several mammalian species (Corpas et al, 1992;Finkelstein et al, 1972;Muller et al, 2002;Rudman, 1985;Wilshire et al, 1995;Zadik et al, 1985). In dogs too the GH responsiveness to GH stimuli, such as GHRH and hexarelin, decreases with ageing (Cella et al, 1989(Cella et al, , 1995.…”

Section: Introductionmentioning

confidence: 99%

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Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

Bhatti

Duchateau

Ham

et al. 2006

The Veterinary Journal

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The effects of three growth hormone secretagogues (GHSs), ghrelin, growth hormone-releasing peptide-6 (GHRP-6), and growth hormone-releasing hormone (GHRH), on the release of adenohypophyseal hormones, growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinising hormone (LH), prolactin (PRL) and on cortisol were investigated in young and old healthy Beagle dogs.Ghrelin proved to be the most potent GHS in young dogs, whereas in old dogs GHRH administration was associated with the highest plasma GH concentrations. The mean plasma GH response after administration of ghrelin was significantly lower in the old dogs compared with the young dogs. The mean plasma GH concentration after GHRH and GHRP-6 administration was lower in the old dogs compared with the young dogs, but this difference did not reach statistical significance. In both age groups, the GHSs were specific for GH release as they did not cause significant elevations in the plasma concentrations of ACTH, cortisol, TSH, LH, and PRL. It is concluded that in young dogs, ghrelin is a more powerful stimulator of GH release than either GHRH or GHRP-6. Ageing is associated with a decrease in GH-releasing capacity of ghrelin, whereas this decline is considerably lower for GHRH or GHRP-6.

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Section: Ghrp-6contrasting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

Bhatti

Duchateau

Ham

et al. 2006

The Veterinary Journal

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“…It is well known that GH secretion also has a nocturnal increment in humans [7]. Therefore, it was hypothesized that MEL could be involved in the increase in GH during the night.…”

Section: Discussionmentioning

confidence: 99%

Effect of Melatonin Injected into the Third Ventricle on Growth Hormone Secretion in Holstein Steers

Kasuya

Kushibiki

Sutoh

et al. 2006

The Journal of Veterinary Medical Science

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ABSTRACT. The effects of melatonin (MEL) injection into the third ventricle (3V) on growth hormone (GH) secretion were investigated in conscious Holstein steers. A stainless steel cannula was stereotaxically implanted in the 3V based on the ventriculogram. In Exp. 1, three doses of MEL (100, 300 or 600 µg) were injected into the 3V through the cannula and the GH concentration after the injection was determined. In Exp. 2, intracerebroventricular (icv) and intravenous (iv) injections of MEL (100 µg) and GH-releasing hormone (GHRH; 0.25 µg/kg body weight), respectively, were performed simultaneously to examine the effect of MEL on GHRH-induced GH release. The icv injection of MEL significantly stimulated GH release at 100 µg. The increase in GH concentrations by 100 µg of MEL was persistent. Intravenous injection of GHRH dramatically increased GH release. The injection of MEL did not alter GHRH-induced GH release. These results suggest that MEL stimulates GH secretion possibly through the hypothalamus in cattle. KEY WORDS: cattle, melatonin, somatotropic axis, stereotaxic, third ventricle.J. Vet. Med. Sci. 68(10): 1075-1080, 2006 Growth hormone (GH) is a very important factor for livestock production [6]. GH-releasing hormone (GHRH) and somatostatin (SS) from the hypothalamus are primary factors controlling GH secretion in mammals. In addition to GHRH and SS, many neuromodulators have been considered to be involved in GH release regulation in many species. Although the central regulatory mechanism of GH secretion has been studied in sheep using hypophyseal portal blood sampling technique [4], such information is not well obtained in cattle.The evidences have shown the possibility that melatonin (MEL) from the pineal gland is one of those factors controlling GH secretion; however, the exact effect of MEL on GH secretion is controversial. For example, in humans it was reported that MEL induced an increase in GH levels [27,29]; however, other groups obtained no effects of MEL on GH secretion [13,31]. The intramuscular injection of MEL decreased GH secretion in prepubertal boys and the same dose of MEL increased GH level in some pubertal subjects [17]. In vitro experiments showed that MEL reduced GH secretion from rat pituitary cells [8]. These variations of the effects of MEL on GH secretion could be caused by the differences in the experimental and physiological conditions, and there might be inter-species differences regarding the role of MEL in the regulation of GH secretion.The purpose of the present study was to determine the role of MEL in the regulatory system of GH secretion in cattle. Since MEL has been reported to stimulate GH release via the hypothalamus [23,29], the technique for the direct injection of MEL into the third ventricle (3V) at three doses (100, 300 and 600 µg) was used. We also assessed whether MEL affects GHRH-induced GH release to reveal the involvement of the hypothalamus in GH secretion modulated by MEL. MATERIALS AND METHODS Animals:Eleven Holstein steers (7 to 8 mo old at the time of su...

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“…However, we have recently shown that growth hormone enhances cathepsin D and acid phosphatase in cartilage of Hx rats (20). Since growth hormone secretion appears to diminish with age (21,22), the initial decline in cartilage cathepsin D and acid phosphatase activities with age could be related in part to their growth hormone-dependence. Interestingly, however, at 25 weeks of age normal enzyme activities appeared to be even lower than that of the hypophysectomized animals (Fig.…”

Section: Discussionmentioning

confidence: 95%

Alteration of Cartilage Lysosomal Enzyme Activities during Development. (acid hydrolases/cartilage development/cartilage growth/hypophysectomy)

Hubbard¹,

Liberti²

1982

Dev Growth Differ

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Cartilage cathepsin D, cathepsin B and acid phosphatase activities decreased with maturation of Sprague-Dawley rats. Although this phenomenon may largely be due to an age-dependent decrease in cell concentration at young ages (1-8 weeks), in older (8-25 weeks) rats there appeared to be a decrease in enzyme activity per cell.' The dimunition in cartilage cathepsin D activity coincided with an apparent decrease in its concentration. In addition, the inverse correlation between rat age and cartilage lysosomal enzyme activities was, at least in part, tissue specific as the pattern of liver lysosomal enzyme activities was quite different from that noted with cartilage. Interestingly, hypophysectomy greatly diminished age-related modulations in lysosomal enzyme activities suggesting that one or more pituitary hormones may be involved in the mechanism of this age-dependent phenomenon. In addition, cartilage grow;h rate appeared to be correlated with the level of cartilage lysosomal enzyme activities, indicating that these enzymes may be related to the biochemical mechanism of cartilage growth and development.Lysosomes contain many degradative enzymes which function optimally at acidic pH. Although these enzymes were first thought to be involved in cell autolysis, it is becoming increasingly apparent that they may play vital roles in the biochemical mechanism of many normal and pathological processes (1, 2).Developmental changes in lysosomal enzymes have been examined primarily .in liver (3, 4) and cardiac (5) tissues. Cartilage lysosomal enzymes have been highly studied with regard to certain pathological disorders such as osteoarthritis (6). However, age-related perturbations of cartilage lysosomal enzymes have not been well characterized. Examination of cartilage lysosomal enzyme changes with age could lead to important insights regarding the mechanism of cartilage growth, development and pathology.Recently, we found that a nonspecific cartilage acid protease activity was age-dependent (7). The primary purpose of the present investigation was to characterize developmental changes of specific lysosomal enzymes in rat cartilage. Our results show that cartilage (but not liver) cathepsin D, acid phosphatase, and cathepsin B activities decrease with age. In addition, these alterations in enzyme activities were significantly depressed in hypophysectomized rats suggesting that one or more pituitary hormones may be involved in the mechanism of these age-related metabolic changes.

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Age-Related Change in the Twenty-Four Hour Spontaneous Secretion of Growth Hormone

Cited by 660 publications

References 0 publications

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

Effect of Melatonin Injected into the Third Ventricle on Growth Hormone Secretion in Holstein Steers

Alteration of Cartilage Lysosomal Enzyme Activities during Development. (acid hydrolases/cartilage development/cartilage growth/hypophysectomy)

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