Domestic cats show episodic variation in plasma concentrations of adrenocorticotropin, α-melanocyte-stimulating hormone (α-MSH), cortisol and thyroxine with circadian variation in plasma α-MSH concentrations

1996 ◽  
Vol 134 (5) ◽  
pp. 602-609 ◽  
Author(s):  
Robert J Kemppainen ◽  
Mark E Peterson
Keyword(s):  
Plasma Sample ◽  
Plasma Concentrations ◽  
Circadian Variation ◽  
Pars Intermedia ◽  
Cortisol Secretion ◽  
Domestic Cats ◽  
Melanocyte Stimulating Hormone ◽  
Circadian Change ◽  
Peptide Secretion ◽  
Stimulating Hormone

Kemppainen RJ. Peterson ME. Domestic cats show episodic variation in plasma concentrations of adrenocorticotropin, α-melanocyte-stimulating hormone (α-MSH), cortisol and thyroxine with circadian variation in plasma α-MSH concentrations. Eur J Endocrinol 1996:134:602–9. ISSN 0804–4643 Blood samples were collected from 31 healthy domestic cats to characterize possible episodic and/or circadian variation in plasma concentrations of adrenocorticotropin (ACTH), cortisol, thyroxine and α-melanocyte-stimulating hormone (α-MSH). Samples were collected with minimal disturbance through indwelling jugular cannulae at two frequencies: at 20-min intervals for 3 h for evaluation of episodic variation, and at 2-h intervals for 48 or 72 h to identify possible circadian changes. Episodic peaks in profiles of all hormones were found in the majority of cats. When data were compared across four bleed periods (each of 3 h duration), no differences were detected in average hormone concentrations or characteristics of episodic pulses. Correlation analyses showed a significant (p < 0.001) relationship between concentrations of ACTH and cortisol (r = 0.44) when these hormones were measured in the same plasma sample. A weaker but significant correlation (r = 0.13,p < 0.05) was also detected between concentrations of ACTH and α-MSH, suggesting that proopiomelanocortin peptide secretion from the pars distalis and pars intermedia occurs at least on occasion in synchrony. No differences in hormonal profiles were noted when comparing data across sexes. Data from the studies designed to evaluate circadian change (48 and 72-h bleed periods) indicated that, of the four hormones, only concentrations of α-MSH changed with a significant circadian periodicity. A significant circadian component of period length 24–25 h was detected in 37% (seven of 19) of cats examined. Concentrations of α-MSH were greatest coincident with or shortly after the onset of darkness. These findings indicate that pituitary–adrenocortical hormones are secreted episodically in domestic cats and that, in contrast to the patterns shown by ACTH and cortisol, secretion of the pars intermedia product α-MSH occurs with a circadian rhythm in about one-third of cats. Robert J Kemppainen, Department of Physiology & Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama 36849, USA

Seasonal and photoperiod-induced changes in the secretion of α-melanocyte-stimulating hormone in Soay sheep: temporal relationships with changes in β-endorphin, prolactin, follicle-stimulating hormone, activity of the gonads and growth of wool and horns

1995 ◽  
Vol 144 (3) ◽  
pp. 471-481 ◽  
Author(s):  
G A Lincoln ◽  
B I Baker
Keyword(s):  
Blood Plasma ◽  
Follicle Stimulating Hormone ◽  
Plasma Concentrations ◽  
Fold Increase ◽  
Molar Ratio ◽  
Pars Intermedia ◽  
Soay Sheep ◽  
Melanocyte Stimulating Hormone ◽  
Short Days ◽  
Stimulating Hormone

Abstract Blood plasma concentrations of α-melanocyte-stimulating hormone (α-MSH), β-endorphin (β-END), prolactin and follicle-stimulating hormone (FSH), and associated changes in the size of the testes, and growth of the horns and pelage were measured in male (n=8), castrated male (n=5) and female (n=9) Soay sheep. The animals were born in April and kept outdoors near Edinburgh (56 °N) during the first two years of life. In all groups there was a close association between the weekly changes in the plasma concentrations of α-MSH and β-END; the molar ratio in mean concentrations was close to 1:1. The blood plasma concentrations of both hormones varied markedly with season with a 3- to 10-fold increase in concentrations from the minimum in winter to the maximum in autumn. The seasonal peak occurred in September in the first year of life as juveniles, and between July (males) and September (females) in the second year when the animals were sexually mature. The plasma concentrations of ACTH did not vary in parallel with the seasonal changes in the concentrations of α-MSH (measured only in males); the molar ratio for the concentrations of α-MSH:ACTH was 1:0·12. The seasonal increase in the concentrations of α-MSH occurred 1–3 months after the seasonal increase in the concentrations of prolactin and the associated growth in horns and pelage, and slightly before, or coincident with the seasonal increase in the concentrations of FSH and the growth in the testes. In a second experiment, the same parameters were measured in a group of adult male Soay sheep (n=8) housed indoors under an artificial lighting regimen of alternating 16-week periods of long (16 h light:8 h darkness) and short days (8 h light:16 h darkness). In this situation, there was a clearly defined photoperiod-induced cycle in the plasma concentrations of α-MSH with a 25-fold increase from a minimum under long days to a maximum under short days. The concentrations of β-END varied in close parallel with the changes in α-MSH, and the temporal associations with the changes in the other pituitary hormones were similar to those observed in animals housed outdoors. Overall, the results support the view that α-MSH is co-secreted with β-END from the melanotrophs in the pars intermedia of the pituitary gland, and that the secretory activity of the melanotrophs changes markedly with season, increasing in summer and autumn, and decreasing in winter and spring. The annual cycle in daylength is likely to be the principle environmental cue timing the cycle in α-MSH and β-END. α-MSH is known to have biological effects in the brain (neuroendocrine control of prolactin and FSH), and in the adrenal gland (secretion of glucocorticoids), adipose tissue (fat storage), and skin (melanogenesis and secretion of sebum). Thus the seasonal increase in the secretion of α-MSH may regulate multiple physiological changes in autumn in preparation for winter. Journal of Endocrinology (1995) 144, 471–481

THE EFFECT OF INGESTION OF HYPERTONIC SALINE ON THE MELANOCYTE-STIMULATING HORMONE CONTENT AND HISTOLOGY OF THE PARS INTERMEDIA OF THE RAT PITUITARY GLAND

1970 ◽  
Vol 46 (2) ◽  
pp. 201-NP ◽  
Author(s):  
A. HOWE ◽  
A. J. THODY
Keyword(s):  
Control Level ◽  
Pars Intermedia ◽  
Type I ◽  
Melanocyte Stimulating Hormone ◽  
Level Of Activity ◽  
Numerous Type ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY The changes in the content of melanocyte-stimulating hormone (MSH) and histology of the neuro-intermediate (n.i.) lobe were followed in rats which drank 2% sodium chloride for periods from 1–15 days. The pars intermedia showed a biphasic response. During the initial phase of 1–4 days there was a rapid rise in the MSH content, by 153% in the first day, falling back to control level by 4 days. These fluctuations were paralleled by an increase in the normally small numbers of Type 2 cells and at the same time numerous Type I cells showed hypertrophy and degranulation. After 4 days on saline there was a second rise in the MSH content, which was still evident at 15 days; during this second period the number of Type 2 cells declined to normal levels. The degranulated Type 1 cells also disappeared, most of Type 1 being smaller in size and intensely PAS-positive. After the ingestion of saline it apparently takes several days before the pars intermedia adapts to a new level of activity. The likely significance of these changes and the possibility of a relationship between the pars intermedia and the neurohypophysis are discussed.

scholarly journals Plasma profiles of adrenocorticotropic hormone, cortisol, α-melanocyte-stimulating hormone, and growth hormone in dogs with pituitary-dependent hyperadrenocorticism before and after hypophysectomy

2006 ◽  
Vol 190 (3) ◽  
pp. 601-609 ◽  
Author(s):  
J M Hanson ◽  
H S Kooistra ◽  
J A Mol ◽  
E Teske ◽  
B P Meij
Keyword(s):  
Plasma Cortisol ◽  
Adrenocorticotropic Hormone ◽  
Plasma Concentrations ◽  
Pulse Frequency ◽  
Cortisol Concentration ◽  
Melanocyte Stimulating Hormone ◽  
Plasma Cortisol Concentration ◽  
Before And After ◽  
Basal Plasma ◽  
Stimulating Hormone

The 6-h plasma profiles of adrenocorticotropic hormone (ACTH), cortisol, α-melanocyte-stimulating hormone (α-MSH), and GH were studied in 17 dogs with pituitary-dependent hyperadrenocorticism (PDH) before and after hypophysectomy. The aim of the study was to investigate the relation between the hormone profile characteristics and recurrence of PDH after surgery. The hormones were secreted in a pulsatile fashion. The basal plasma cortisol concentration and area under the curve (AUC) for cortisol were significantly higher in the PDH cases than in eight controls. The characteristics of the plasma profiles of ACTH and α-MSH were not significantly different between the PDH cases and the controls. In the PDH cases, less GH was secreted in pulses than in the controls, but the difference was not significant. The basal plasma cortisol concentration, the AUC for ACTH and cortisol, and the pulse frequency of ACTH and cortisol decreased significantly after hypophysectomy for the group of PDH cases. The basal plasma concentrations of ACTH and α-MSH, the AUC for α-MSH, and the characteristics of the plasma GH profiles of the PDH cases remained unchanged after hypophysectomy. No pulses of α-MSH were observed after hypophysectomy. The co-occurrence between the ACTH and cortisol pulses decreased significantly with hypophysectomy. The postoperative pulse frequency of ACTH was the only characteristic with predictive value for the recurrence of PDH after hypophysectomy. The results of this study demonstrate that ACTH, cortisol, α-MSH, and GH are secreted in a pulsatile fashion in dogs with PDH. Hypophysectomy effectively reduces the secretion of ACTH and cortisol. The presence of ACTH pulses after hypophysectomy is a risk factor for the recurrence of hyperadrenocorticism.

SYNTHESIS AND SECRETION OF A LARGE GLYCOPROTEIN IN THE PARS INTERMEDIA

1975 ◽  
Vol 65 (2) ◽  
pp. 225-231 ◽  
Author(s):  
C. R. HOPKINS
Keyword(s):  
Molecular Weight ◽  
Xenopus Laevis ◽  
Intracellular Transport ◽  
Pars Intermedia ◽  
Secretory Product ◽  
Melanocyte Stimulating Hormone ◽  
Leucine Residue ◽  
Large Molecular Weight ◽  
Stimulating Hormone

SUMMARY The biosynthesis, intracellular transport and release of [3H]leucine-containing secretory product has been followed in the pars intermedia of Xenopus laevis and, in particular, the synthesis and secretion of a large molecular weight glycoprotein secretory product was demonstrated. However, if Xenopus adrenocorticotrophin does contain a leucine residue the results obtained provided no support for the view that it serves as a precursor for melanocyte-stimulating hormone in this species.

Sign in / Sign up

Export Citation Format

Share Document