Neuro Endocrinology

Neuro
Endocrinology

   

• I
  Shimon, X Yan, S Melmed (Univ of California, Los
  Angeles)
  
  Human
  Fetal Pituitary Expresses Functional Growth
  Hormone-Releasing Peptide Receptors.
  J Clin Endocrinol
  
  Metab
  83:174-178, 1998.
  
   
  
  Background-
  The synthetic hexapeptide (GH)-releasing peptide (GHRP)
  induces a dose-dependent release of GH in humans and
  animals through a specific receptor in the
  hypothalamus and pituitary glands.
  
      

• Campino
  C, Torres C, Ampuero S, et al (Pontificia Universidad
  Catolica de Chile, Casilla; Instituto Chileno de
  Medicina Reproductiva, Santiago, Chile)
  
  Bioactivity
  of Prolactin Isoforms: Lactation and Recovery of
  Menses in Nursing Women.
  
  Hum
  Reprod 14; 898-905, 1999
  
    
  
  Background
  :
  Among women, breastfeeding may coexist with amenorrhea
  or with normal menstrual cycles.
  The factors associated with the resumption of
  menstrual cycles during lactation are not well
  understood. Whether
  differences in plasma prolactin (PRL) isoforms relate
  to the resumption of menses during lactation by
  comparing PRL isoforms between amenorrheic and cycling
  nursing women was examined.
  
    
  
  Conclusions:
  The results demonstrate that lactation in the presence
  or absence of menses is associated with differences 
  in plasma BIO-PRL and in the presence of
  particular PRL isoforms.
  The main difference between amenorrheic and
  cycling nursing women was the presence of BIO-PRL
  eluting at pH 7 to 6.1, with a high BIO/IR (Immunoreceptive)
  ratio exclusively in the amenorrheic nursing women.
  
      

• Barkan
  AL, Chandler WF (Univ of Michigan, Ann Arbor)
  
  Giant
  Pituitary Prolactinoma with Falsely Low Serum
  Prolactin: The Pitfall of the “High-Dose Hook
  Effect” : Case Report.
  
  Neurosurgery
  42: 913-916, 1998
  
   
  
  Background
  : In most clinical laboratories, current practice is
  to measure prolactin using 2-site monoclonal
  immunoradiometric assay (IRMA) or chemiluminometric
  assay (ICMA). Though these assays are more rapid, accurate, and specific than the
  earlier radioimmunoassays, they have a pitfall that
  may severely compromise their performance and provide
  a grossly accurate measure of prolactin excess.
  
    
  
  Conclusion:
  Clinicians should consider the presence of a high-dose
  hook effect in all patients with pituitary adenomas
  larger than 3 cm and normal serum prolactin
  concentration. Subsequent
  assay of diluted serum will reliably demonstrate this
  phenomenon, enabling correct diagnosis and treatment.
  
      

• Verhelst
  J, Abs R, Maiter D, et al (Middelheim Ziekenhuis,
  Antwerp, Belgium; Universitair Ziekenhuis, Antwerp;
  Cliniques Universitaires St-Luc, Brussels, Belgium; et
  al)
  
  Cabergoline
  in the Treatment of Hyperprolactinemia: A Study in 455
  Patients.
  
  J
  Clin Endocrinol Metab 
  84:2518-2522, 1999.
  
   
  
  Background:
  Cabergoline is a new long-acting dopamine agonist that
  is being used in the treatment of patients with
  pathologic hyperprolactinemia.
  It appears to be well-tolerated and very
  effective against the clinical symptoms and visual
  field abnormalities and in shrinking the tumor.
  Cabergoline’s longer half-life and increased
  patient tolerability seem to give it several
  advantages over bromocriptine.
  However, few clinical studies have been done on
  this drug. The
  experience of a group of patients with pathologic
  hyperprolactinemia treated with cabergoline, and a
  subgroup treated with cabergoline who were intolerant
  of or resistant to bromocriptine, was examined.
  
    
  
  Results
  :  Serum PRL levels returned to normal for 86% of all patients
  treated with cabergoline, specifically for 92% of the
  patients with idiopathic hyperprolactinemia or
  microprolactinomas, and for 77% of aptietns with
  macroadenomas. Serum
  PRL levels were normalized for 70% of the
  bromocriptine-resistant and 84% of the bromocriptine-intolerant
  patients. Visual
  field abnormalities evident before cabergoline
  treatment were normalized for 70% of patients.
  For 67% of the patients, tumor shrinkage was
  noted.
  
    
  
  Although
  side effects were experienced by 13% of patients, only
  3.95 discontinued use of cabergoline. In 89% of the women (227 of 254), the menstrual cycle returned to
  normal, and 27 of the patients became pregnant, with
  25 healthy deliveries, 1 elective abortion, and 1
  miscarriage.
  
    
  
  Conclusions-
  Cabergoline demonstrated a high degree of efficacy and
  tolerability in this large-scale study.
  There were few instances of unacceptable side
  effects or inadequate clinical response.
  Cabergoline was highly effective in normalizing
  PRL secretion in the total group and among patients
  intolerant of or resistant to bromocriptine.
  The cost of therapy could be reduced, since
  dosage could be lowered significantly once PRL
  secretion was under control.
  
    
  
  Freda
  et al remind us that pergolide is also an excellent
  treatment for prolactinomas, even if it is not
  FDA-approved for this use.
  
    
  
  Another
  nice series recently reported was that of patients
  with cysts occurring in the hypothalamus (21
  craniopharyngiomas, 26 Rathke’s cleft cysts, and 5
  arachnoid cysts) seen at the University of Toronto.
  The fact that many of these patients had
  hyperprolactinemia (38% of craniopharyngiomas, 46% of
  Rathke’s cleft cysts, and 20% of arachnoid cysts.        
  
                                                                                                                       

• Landolt AM, Haller D, Lomax N, et al (Klinik im Park, Zurich, Switzerland)   
  
  Octreotide May Act As a Radioprotective Agent in Acromegaly     
  
  J Clin Endocrinol Metab 85: 1287-1289, 2000 
  
                                                                                   
  
  Patients with acromegaly can be treated by:     
  
  (1) Microsurgery    
  
  (2) Antisecretory drugs (octreotide)    
  
  (3) Radiation therapy         
  
  in order to decrease circulating levels of GH and insulin-like growth factor I(IGF-I) to normal levels.         
  
                                                                                  
  
  This retrospective study was conducted on 31 patients with acromegaly to determine the effect of octreotide therapy on the results of stereotactic surgery.
  
                                                           
  
  It was found that octreotide therapy has a radioprotective effect on the pituitary adenomas of patients, with acromegaly. Hence, it is recommended that patients should not receive octreotide, when stereotactic radiosurgery is done. Octreotide can be started or resumed after completion of
  radiosurgery.                    
  
                                                 

• Kojima M, Hosoda H, et al (Natl Cardiovascular Ctr Research Inst, Osaka, Japan; Miyazaki Med College, Japan)
  
  Ghrelin is a Growth-Hormone-Releasing Acylated Peptide From Stomach
  
  Nature 402: 656-660, 1999
  
                                    
  
  Release of growth hormone (GH) from the pituitary is stimulated by GH secretagogues (GHSs) that act through a G-protein -coupled receptor (GHS-R)
  
                                                
  
  Ghrelin found in the rat stomach, function as an endogenous ligand specific for GHS-R
  
                                                  
  
  GH releasing hormone (GHRH) had no effect on cells potently induced by ghrelin to increase intracellular calcium concentration; ghrelin inhibited the action of an antagonist, raising calcium concentration back to preantagonist levels.
  
                                               
  
  In humans, the GH-releasing activity of ghrelin compared favourably with GHRH. When ghrelin was injected into anaesthetized rats, only GH concentrations rose to maximal levels, indicating ghrelins specifity for GH.
  
                                                      
  
  The authors concluded that release of GH from the pituitary may be regulated by both hypothalamus GHRH and
  ghrelin.     
  
                                                                                                                                                               

• Beuschlein F,Strasburger CJ et al (Klinikum der Albert Ludwigs-Universitat Freiburg, Germany; Klinikum Innenstadt der Ludwig-Maximilians-Universitat, Munich; German Cancer Research Ctr, Heidelberg, Germany)     
  
  Acromegaly caused by secretion of growth hormone by a non-Hodgkin’s lymphoma.     
  
  N Engl J Med 342: 1871-1876, 2000
  
                                                                         
  
  This is a case report of a patient with recurrent non-Hodgkin’s lymphoma and acromegaly resulting from ectopic production of GH by the lymphoma. The lymphoma was strongly immunoreactive to GH