Influence of age and splanchnic nerve on glucagon-induced changes of adrenomedullary catecholamine content and blood glucose level in the avian group
01 Sep 1991-Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology (Springer Nature)-Vol. 161, Iss: 5, pp 532-536
TL;DR: The results indicate that the splanchnic nerve regulates release and/or resynthesis of CA induced by glucagon and that aging modulates glucagon-induced changes of catecholamine (CA) content.
Abstract: Glucagon (0.1 mg · 100 g body wt-1) increased norepinephrine (NE) content in adult pigeon (31%) and parakeet (58%), decreased NE content in the adrenal medulla of newly-hatched pigeon (36%), parakeet (52%), and crow (44%) 0.5 h after treatment. Epinephrine (E) content decreased to 26% and 59% of control values, respectively, in newly-hatched pigeon and parakeet 0.5 h after treatment. Glucagon produced hyperglycemia irrespective of age and species. The results indicate that aging modulates glucagon-induced changes of catecholamine (CA) content. In the innervated (I) adrenal gland of pigeon, glucagon caused a 31% increase of NE content 0.5 h after injection, a 46% decrease of NE content 12 h after injection, and a 192% increase of NE 24 h after injection. In the I gland of pigeons, glucagon also caused a 61% decrease of E content 4 h after injection, and brought about a 100% increase of E 24 h after injection. Glucagon-induced changes of CA content differ significantly between the I and denervated (D) glands. The results indicate that the splanchnic nerve regulates release and/or resynthesis of CA induced by glucagon.
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89 citations
01 Jan 2001
TL;DR: Although progress has been made, it is apparent that research on the avian adrenal medulla still lags behind work on the mammalian organ.
Abstract: The purpose of this review is to explore the world literature on the avian adrenal medulla from the last 20 years. Unlike the mammalian adrenal medulla, the adrenal gland in birds has chromaffin cells mixed with cortical cells. Studies have investigated the ultrastructure (both transmission and scanning electron microscopy), biochemistry, and physiology (partic- ularly interactions with other endocrine glands) of the avian adrenal medulla. Although progress has been made, it is apparent that research on the avian adrenal medulla still lags behind work on the mammalian organ.
15 citations
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TL;DR: It is concluded that the elevation of tyrosine hydroxylase is mediated by a prolonged reflex increase in the splanchnic nerve activity as a consequence of drug-induced impairment of postganglionic sympathetic transmission.
Abstract: Pretreatment of rats with 6-hydroxydopamine, reserpine and phenoxybenzamine, drugs which interfere with postganglionic sympathetic transmission by different mechanisms, induces an increase in the in vitro adrenal tyrosine hydroxylase activity. This increase in the rate-limiting enzyme in catecholamine synthesis can be prevented by interruption of the splanchnic nerves supplying the adrenal glands, whereas an elevation of the enzyme activity is still present in hypophysectomised animals. Adrenal denervation also partially prevents the depletion of catecholamines caused by reserpine and phenoxybenzamine. It is concluded that the elevation of tyrosine hydroxylase is mediated by a prolonged reflex increase in the splanchnic nerve activity as a consequence of drug-induced impairment of postganglionic sympathetic transmission.
281 citations
"Influence of age and splanchnic ner..." refers background in this paper
...Analogous findings (CA content) were also reported in rats (Thoenen et al. 1969)....
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TL;DR: It is suggested that the co-existence of hyperglucagonemia and hyperinsulinemia may tend to favor incorporation of glucose into adipose tissue rather than muscle, and the failure of forearm A-V blood glucose differences to reflect accurately total peripheral glucose assimilation under these experimental conditions is discussed.
Abstract: Glucagon in doses of 0.25 or 1.0 mg. was injected rapidly, intravenously, into healthy normal subjects. There was a striking rise in arterial immunoreactive insulin levels within one minute of the start ot the injection before any change in arterial glucose concentration occurred Plasma insulin levels reached their peak within ten minutes and began to fall thereafter. In contrast, blood glucose levels were highest twenty to thirty minutes after the injection. A second glucagon injection during the hyperglycemic phase produced a larger rise in plasma insulin than the first. During constant infusions of smaller amounts of glucagon, the insulinogenic effect of glucagon was usually only apparent if blood glucose levels were raised. The effect of consecutive forty-minute intravenous infusions of glucagon (10μg./min.), glucose (0.5 gm./min.) and a glucagon-glucose (5μg. and 250 mg./min., respectively) on plasma insulin and arterio-venous blood glucose differences in six healthy normal subjects was studied. Plasma insulin levels were two to five times higher during glucose infusions alone, despite similar peak arterial blood glucose levels during the infusions. Similar results were obtained in other subjects during separate infusions of glucose and glucagon. Total body glucose clearance, judged by the rate of fall in arterial blood glucose levels, was faster after glucagon- than after glucose-induced hyperglycemia. Forearm A-V blood glucose differences were not obviously greater during glucagon, in spite of the higher plasma insulin levels, than during glucose infusions. Possible reasons for the failure of forearm A-V blood glucose differences to reflect accurately total peripheral glucose assimilation under these experimental conditions are discussed, and it is suggested that the co-existence of hyperglucagonemia and hyperinsulinemia may tend to favor incorporation of glucose into adipose tissue rather than muscle. Plasma glucagon levels were measured by immunoassay and the half-life was about ten minutes. The results provide evidence of a direct effect of glucagon upon insulin secretion. The suggestion is made that the insulinogenic effect of glucagon is physiological importance and is due to accelerated intra-β-cell glycogenolysis.
184 citations
TL;DR: The fluorometric procedure developed in the laboratory allows the rapid determination of the levels, in a single sample, of what are considered to be the major biogenic amines-norepinephrine, dopamine, and serotonin, as well as the latter’s major metabolite, 5-hydroxyindoleacetic acid.
Abstract: OVER the last decade the role of biogenic amines and their metabolites in the brain has been the subject of considerable interest with regard to the relationship of these substances to the actions of various drugs (CARISSON, 1964), alterations of behaviour (SCHILDKRAUT and KETY, 1967), and such disease entities as hypertension (SMOOKLER and BUCKLEY, 1969). However, until recently it was necessary to perform one assay for the determination of norepinephrine and dopamine (CHANG, 1964) and another for the measurement of serotonin (5-hydroxytryptamine) and 5-hydroxy-3indoleacetic acid (AHTEE et al., 1970). Combined assay procedures have been developed for the determinations of norepinephrine and serotonin (MAICKEL et al., 1968) and norepinephrine, dopamine and serotonin (ANSELL and BEESON, 1968; SHELLENRERGER and GORDON, 1971 ; WELCH and WELCH, 1969) but only one (WELCH and WELCH, 1969) includes the possibility for determination of 5-hydroxyindoleacetic acid, the chief metabolite of serotonin. The fluorometric procedure developed in our laboratory allows the rapid determination of the levels, in a single sample, of what are considered to be the major biogenic amines-norepinephrine. dopamine, and serotonin, as well as the latter’s major metabolite, 5-hydroxyindoleacetic acid. This assay utilizes the adsorption of the catecholamines onto alumina to remove noncatechol fluorescent substances, as described by CHANG (1964); the extraction of serotonin similar to that described by ANSELL and BEESON (1968); the development of a solvcnt extraction for 5-hydroxyindoleacetic acid; and utilization of the o-phthaldialdchyde reaction described by MAICKEL et al. (1968) for the determination of serotonin and 5-hydroxyindoleacetic acid. The value of obtaining data on discrete areas of the brain rather than from the whole brain has been shown to be of considerable importance (MILLER et al., 1968; HANK and APRISOS, 1971). Our procedure has been designed for application to the brain, but could be applied to other tissues and urine. In addition to measurement of the substances described, this assay could also be used for the determination of epinephrine with the appropriate adjustment of the standards (Cmrici, 1964).
159 citations
89 citations
TL;DR: Data are in accord with the conclusion that the hyperglycemic response to glucagon is the resultant of the combined effects of rapid hepatic glycogenolysis and stimulation of the release of epinephrine, which acts to depress the rate of glucose uptake by peripheral tissues.
Abstract: A single injection of glucagon (50 μg/kg) given to anesthetized dogs rapidly elevates glucose, lactate and epinephrine levels in peripheral plasma. A 10-min infusion of glucagon (0.1 mg/min) produced a marked elevation of both epinephrine and norepinephrine in adrenal vein blood. These data are in accord with the conclusion that the hyperglycemic response to glucagon is the resultant of the combined effects of rapid hepatic glycogenolysis and stimulation of the release of epinephrine, which acts to depress the rate of glucose uptake by peripheral tissues. Evidence for the postulate that hypoglycemia stimulates release of glucagon, which in turn elicits the release of epinephrine, is discussed.
65 citations
"Influence of age and splanchnic ner..." refers result in this paper
...Earlier workers have reported analogous findings in adult mammals (Scian et al. 1960; Sarcione et al. 1963; Lupulescu et al. 1966)....
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