Tag: dopamine

Characterization of pituitary function with emphasis on GH secretion in the chronic fatigue syndrome

Abstract:

OBJECTIVE: Previous studies have revealed that hormonal disturbances may accompany the chronic fatigue syndrome (CFS). Changes in the secretion of the pituitary-adrenal axis have been demonstrated, as well as abnormalities in the GH-IGF-I axis. However, data have not always been well characterized and were sometimes conflicting. The small number of CFS patients investigated in earlier studies may have played a role in the interpretation of the results.

SUBJECTS AND DESIGN: Hormonal testing was performed in 73 nonobese CFS patients and nonobese 21 age-and gender-matched healthy controls. We investigated GH, ACTH and cortisol responses to insulin-induced hypoglycaemia. In a subgroup of patients arginine and clonidine stimulation for GH was also performed. Nocturnal secretion of GH, ACTH and cortisol were determined. Serum levels of IGF-I, prolactin, TSH, and free thyroxine were also measured. Visceral fat mass was assessed by CT scanning.

RESULTS: GH response to insulin induced hypoglycaemia assessed by peak value (17.0 +/- 13.1 microg/l vs. 22. 1 +/- 9.8 microg/l; P = 0.01) and by AUC (450.0 +/- 361.3 microg/l vs. 672.3 +/- 393.0 microg/l; P = 0.002) was significantly decreased in CFS patients vs. controls. Nocturnal GH secretion assessed by GH peak value (5.4 +/- 3.7 vs. 9.0 +/- 5.1 microg/l; P = 0.44) and by AUC (34.4 +/- 20.2 vs. 67.4 +/- 43.1; P = 0.045) was also significantly impaired in CFS patients. Arginine and clonidine administration showed no differences in GH secretion between CFS patients and controls. In the CFS group, GH peak values were significantly higher after ITT than after arginine (P = 0.017) or clonidine (P = 0.001). No differences in serum IGF-I levels were found between CFS patients and controls. Except for a significantly lower nocturnal cortisol peak value, no differences were found in ACTH and cortisol secretion between CFS patients and controls. Significantly higher serum prolactin levels (7.4 +/- 4.7 microg/l vs. 4.4 +/- 1.3 microg/l; P = 0.004) and significantly higher serum TSH levels (1.6 +/- 1.0 mU/l vs. 1.0 +/- 0.4 mU/l; P = 0.011) were found in CFS patients. Serum free thyroxine was comparable in both groups. Visceral fat mass was significantly higher in CFS patients (86.6 +/- 34.9 cm2 vs. 51.5 +/- 15.7 cm2; P < 0.001).

CONCLUSIONS: We observed a significant impairment of GH response during insulin-induced hypoglycaemia and a low nocturnal GH secretion in CFS patients. These changes did, however, not lead to different concentrations in serum IGF-I. The clinical expression of this inadequate GH secretion can thus be questioned, although the alteration in body composition may be related to this relative GH deficiency. Significantly increased prolactin and TSH levels were found when compared to controls. These findings give support to the hypothesis of a decreased dopaminergic tone in CFS. Further investigations are required in order to identify specific adaptations within the neurotransmitter system in CFS and to determine the clinical importance of the impaired GH homeostasis.

 

Source: Moorkens G, Berwaerts J, Wynants H, Abs R. Characterization of pituitary function with emphasis on GH secretion in the chronic fatigue syndrome. Clin Endocrinol (Oxf). 2000 Jul;53(1):99-106.http://www.ncbi.nlm.nih.gov/pubmed/10931086

 

Parallels between post-polio fatigue and chronic fatigue syndrome: a common pathophysiology?

Abstract:

Fatigue is the most commonly reported and most debilitating of post-polio sequelae affecting the >1.8 million North American polio survivors. Post-polio fatigue is characterized by subjective reports of difficulty with attention, cognition, and maintaining wakefulness. These symptoms resemble those reported in nearly 2 dozen outbreaks of post-viral fatigue syndromes (PVFS) that have recurred during this century and that are related clinically, historically, anatomically, or physiologically to poliovirus infections.

This article reviews recent studies that relate the symptoms of post-polio fatigue and chronic fatigue syndrome (CFS) to clinically significant deficits on neuropsychologic tests of attention, histopathologic and neuroradiologic evidence of brain lesions, impaired activation of the hypothalamic-pituitary-adrenal axis, increased prolactin secretion, and electroencephalogram (EEG) slow-wave activity.

A possible common pathophysiology for post-polio fatigue and CFS, based on the Brain Fatigue Generator Model of PVFS, and a possible pharmacotherapy for PVFS based on replacement of depleted brain dopamine, will be described.

 

Source: Bruno RL, Creange SJ, Frick NM. Parallels between post-polio fatigue and chronic fatigue syndrome: a common pathophysiology? Am J Med. 1998 Sep 28;105(3A):66S-73S. http://www.ncbi.nlm.nih.gov/pubmed/9790485

 

Increased prolactin response to buspirone in chronic fatigue syndrome

Abstract:

We studied the endocrine and subjective responses that followed acute administration of the 5-HT1A receptor agonist buspirone (0.5 mg/kg orally) in 11 male patients with chronic fatigue syndrome (CFS) and a group of matched healthy controls.

Patients with CFS had significantly higher plasma prolactin concentrations and experienced more nausea in response to buspirone than did controls. However, the growth hormone response to buspirone did not distinguish CFS patients from controls.

Our data question whether the enhancement of buspirone-induced prolactin release in CFS is a consequence of increased sensitivity of post-synaptic 5-HT1A receptors. It is possible that the increased prolactin response to buspirone in CFS could reflect changes in dopamine function.

 

Source: Sharpe M, Clements A, Hawton K, Young AH, Sargent P, Cowen PJ. Increased prolactin response to buspirone in chronic fatigue syndrome. J Affect Disord. 1996 Nov 4;41(1):71-6. http://www.ncbi.nlm.nih.gov/pubmed/8938208

 

Postviral fatigue syndrome

Comment on: Possible upregulation of hypothalamic 5-hydroxytryptamine receptors in patients with postviral fatigue syndrome. [BMJ. 1992]

 

EDITOR,-A M 0 Bakheit and colleagues report an enhanced prolactin response to buspirone in patients with postviral fatigue syndrome and suggest this may be due to upregulation of hypothalamic 5-hydroxytryptamine receptors. They fail to mention the considerable evidence indicating that the drug is a moderately potent dopamine antagonist, a pharmacological action which suggests an alternative explanation for their data.

They administered a single 60 mg dose of buspirone-in excess of the daily maximum of 45 mg recommended by the British National Formulary-so antidopaminergic effects may well have been significant in their studies. The fact that the prolactin releasing effect of buspirone can be blocked by the drug metergoline does not prove 5-hydroxytryptamine receptor specificity. Indeed, metergoline is used commonly as an alternative dopamine agonist to bromocriptine in managing hyperprolactinaemia. Thus enhanced prolactin release after buspirone in postviral fatigue syndrome may reflect, at least in part, inhibition of increased hypothalamic dopaminergic tone on the  It would be interesting to study the same groups of patients using a specific D2 dopamine antagonist (such as domperidone) to see whether this is the case.

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1882431/pdf/bmj00077-0052d.pdf

 

Source: Bevan JS. Postviral fatigue syndrome. BMJ. 1992 Jun 13;304(6841):1566; author reply 1567. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1882431/