Abstract. Histamine, which acts as a neurotransmitter, stimulates the release of the pro-opiomelanocortin derived peptides ACTH, β-lipotropin, and β-endorphin. Since stress affects the hypothalamic turn-over of neuronal histamine, we investigated the role of histaminergic neurons in the mediation of the stress-induced release of ACTH and β-endorphin immunoreactivity in male rats. In control animals histamine receptor antagonists had no effect on the release of ACTH or β-endorphin immunoreactivity. Restraint and ether stress increased plasma ACTH 3- and 2-fold, respectively. The responses were almost prevented by intracerebroventricular or intra-arterial infusion of the H2-receptor antagonists cimetidine and ranitidine. Infused intracerebroventricularly the H1-receptor antagonist mepyramine inhibited the ACTH response to restraint by 45% (P< 0.01), but had no effect on the response to ether. Infused intra-arterially the H1-receptor antagonists mepyramine or SKF-93944 had no effect. Restraint and ether stress increased plasma β-endorphin immunoreactivity 6- and 5-fold, respectively. Sephadex G-50 gel chromatography of plasma showed that the β-endorphin immunoreactivity in stressed rats coeluted with β-lipotropin and β-endorphin, whereas the immunoreactivity in control animals co-eluted almost exclusively with β-endorphin. The H2-receptor antagonists cimetidine and ranitidine infused intracerebroventricurlarly inhibited the responses of β-endorphin immunoreactivity to restraint and ether stress by 90 and 70%, respectively, whereas intra-arterial infusion of these antagonists inhibited the responses by only 50 and 60%, respectively. The H1-receptor antagonist mepyramine infused intracerebroventricularly inhibited the β-endorphin immunoreactivity response to restraint and ether stress by 40 and 25%, respectively, whereas intra-arterial infusion of mepyramine or the other H1-receptor antagonist SKF-93944 prevented the response to restraint stress, but had no effect on the response to ether stress. We suggest that hypothalamic histamine is involved in the mediation of the stress-induced release of the proopiomelanocortin-derived peptides ACTH, β-endorphin and β-lipotropin. The effect is mediated preferentially via H2-receptors, but H1-receptors may also play a role.
Ulrich Knigge, Steen Matzen, Flemming W. Bach, Peter Bang and Jørgen Warberg
Ulrich Knigge, Flemming W. Bach, Steen Matzen, Peter Bang and Jørgen Warberg
Abstract. In conscious male rats intracerebroventricular infusion of histamine increased the plasma concentrations of ACTH and β-endorphin immunoreactivity 2.5-fold (P < 0.01). Gel filtration of plasma revealed two peaks of β-endorphin immunoreactivity corresponding to β-endorphin and β-lipotropin. The two fractions increased almost equally in histamine-stimulated animals, whereas most of the circulating β-endorphin immunoreactivity in control animals corresponded to β-endorphin. Central infusion of the H1-receptor agonist 2-thiazolylethylamine and of the H2-receptor agonists dimaprit or 4-methylhistamine increased the plasma ACTH and β-endorphin immunoreactivity concentrations 2- and 3-fold, respectively (P < 0.01). Infused intracerebroventricularly, the H2-receptor antagonists cimetidine or ranitidine prevented the histamine-induced increase in plasma ACTH and β-endorphin immunoreactivity (P < 0.01), whereas the H1-receptor antagonist mepyramine inhibited the peptide responses by 70% (P < 0.01). Infused intra-arterially cimetidine or ranitidine inhibited the histamine-induced increase in plasma ACTH by 80% (P < 0.01) and plasma β-endorphin immunoreactivity by 45% (P < 0.05), whereas mepyramine or the other H1-receptor antagonist SKF-93944 inhibited the ACTH response by 50% (P < 0.05), but had no effect on the β-endorphin immunoreactivity. The results indicate that histamine increases the release of the pro-opiomelanocortin derived peptides ACTH, β-lipotropin and β-endorphin from the anterior pituitary lobe, whereas an effect of histamine on the release of β-endorphin from the neurointermediate lobe is possible. The effect of histamine seems primarily mediated by H2-receptors, whereas H 1-receptors appear to play a minor role.
Peter Bang, Ulla Eriksson, Vicki Sara, Inga-Lena Wivall and Kerstin Hall
Insulin-like growth factor binding proteins interfere in the IGF-I and -II radioimmunoassays. In an attempt to overcome this problem, we have compared the use of truncated IGF-I, with reduced IGFBP affinity, and IGF-I as radioligands for IGF-I RIA measurements in serum separated by acid gel filtration or acid ethanol extraction followed by cryo-precipitation. With truncated IGF-I as radioligand the IGF-I measurements in acid gel filtrates and acid ethanol extracts were significantly correlated in healthy subjects (N=42, r=0.91, p<0.001) and in patients with acromegaly (N=10, r=0.85, p<0.01), GH deficiency (N=10, r=0.88, p<0.001) or Type I diabetes mellitus (N=10, r=0.90, p<0.001). In contrast, the IGF-I concentrations in acid ethanol extracts determined with IGF-I as radioligand did not correlate with those in acid gel filtrates using truncated IGF-I radioligand in patients with acromegaly (r=0.61, NS) or GH deficiency (r=0.46, NS). In the latter group the mean IGF-I concentrations measured in acid ethanol extracts were erroneously elevated by 112%. Low-affinity antibodies used for IGF-II RIA determinations failed to give reliable results in acid ethanol extracts from patients with Type I diabetes mellitus or GH deficiency. In conclusion, erroneously high IGF-I concentrations owing to binding of the radioligand to IGFBPs not completely removed by acid ethanol extraction can be avoided by the use of truncated IGF-I as radioligand.
Mikkel G Mieritz, Peter Christiansen, Martin Blomberg Jensen, Ulla N Joensen, Loa Nordkap, Inge A Olesen, A Kirstine Bang, Anders Juul and Niels Jørgensen
Gynaecomastia is a benign proliferation of glandular tissue of the breast; however, it is an important clinical observation because it can be the first symptom of an underlying disease. Some controversy exists concerning the clinical importance of an in-depth investigation of men who develop gynaecomastia. We hypothesise that a thorough work-up is required in adult men with gynaecomastia.
All adult men (n = 818) referred to a secondary level andrological department at Rigshospitalet in Copenhagen, Denmark during a four-year period (2008–2011) under the diagnosis of gynaecomastia (ICD-10: N62) were included.
Thirty-two men who did not have gynaecomastia when examined were excluded; leaving 786 men for final analyses. They underwent an andrological examination, ultrasound of the testicles and analysis of endogenous serum hormones levels.
In 43% of men with adult onset of gynaecomastia (≥18 years) an underlying, and often treatable, cause could be detected. In men younger at onset an underlying cause for gynaecomastia could be detected in merely 7.7%. The study is limited by the fact that we did not have access to investigate men who were referred directly by their GP to private clinics for plastic surgery or who sought cosmetic correction without consulting their GP first.
Our study demonstrates the importance of a thorough examination and provides a comprehensible examination strategy to disclose the underlying pathology leading to the development of gynaecomastia in adulthood.