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Veterinary pathology1990; 27(6); 419-425; doi: 10.1177/030098589902700606

Immunocytochemical demonstration of proopiomelanocortin-derived peptides in pituitary adenomas of the pars intermedia in horses.

Abstract: Adenomas of the pars intermedia from 19 horses and normal pituitary glands from seven horses were evaluated histologically and immunocytochemically for adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin (beta-END), proopiomelanocortin (POMC), prolactin, neuron specific enolase, and glial fibrillary acidic protein (GFAP). The 26 horses ranged in age from 7 to 31 years. Histologically, all adenomas had a uniform pattern characterized by cords of large columnar cells forming palisades and pseudoacini separated by a delicate fibrovascular stroma. Immunostaining of adenomas derived from the pars intermedia was similar to that of non-neoplastic equine pars intermedia. An immunocytochemical evaluation revealed a diffuse, strong cytoplasmic reaction for POMC, a moderate to strong reaction for alpha-MSH and beta-END, a weak reaction for ACTH, and negative immunostaining for prolactin, GFAP, and neuron specific enolase in the adenomas. The unique clinicopathologic syndrome that develops in horses with pituitary adenomas appears to be the result of an over-production of POMC-derived peptides in addition to space-occupying effects resulting in dysfunction of the hypothalamus and neurohypophysis.
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Publication Date: 1990-11-01 PubMed ID: 2177580DOI: 10.1177/030098589902700606Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates pituitary adenomas in horses, specifically identifying the presence of various hormones and proteins in these tumours. The researchers found that the tumours resulted in the over-production of certain peptides, which may be the leading factor in the syndromes developed by horses with these adenomas.

Research Context

  • The researchers evaluated adenomas (benign tumors) of the pars intermedia, a part of the pituitary gland in horses. They examined samples from 19 horses with adenomas and compared them to normal pituitary glands from seven horses.
  • The focus of the investigation was on several hormones and proteins, including adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin (beta-END), proopiomelanocortin (POMC), prolactin, neuron specific enolase, and glial fibrillary acidic protein (GFAP).
  • The horses involved in the study ranged in age from 7 to 31 years.

Findings and Interpretations

  • On examination, all adenomas had a similar pattern composed of large columnar cells forming rows and pseudoacini (false glandular structures) separated by delicate fibrovascular stroma (connective tissue).
  • Upon using an immunocytochemical approach, the researchers were able to observe the response of these adenoma cells to different hormones and proteins.
  • A strong cytoplasmic reaction was detected for POMC, suggesting an overproduction of POMC-derived peptides within the tumour cells.
  • Similarly, a moderate to strong reaction was seen for alpha-MSH and beta-END, which are derived from POMC.
  • There was a weak reaction for ACTH, and no reaction for prolactin, GFAP, and neuron specific enolase. This suggests that these substances were not significantly produced or affected by the adenomas.

Conclusion and Implications

  • From these observations, the researchers concluded that the unique syndrome, likely characterized by certain physical and behavior changes, seen in horses with pituitary adenomas could be a consequence of the overproduction of POMC-derived peptides.
  • This overproduction and presence of these adenomas, by occupying space and causing dysfunction of the hypothalamus and neurohypophysis (parts of the pituitary), can lead to the said syndrome.
  • The findings of this study can help in understanding the pathophysiology of equine pituitary adenomas and potentially aid in the development of targeted treatments.

Cite This Article

APA
Heinrichs M, Baumgärtner W, Capen CC. (1990). Immunocytochemical demonstration of proopiomelanocortin-derived peptides in pituitary adenomas of the pars intermedia in horses. Vet Pathol, 27(6), 419-425. https://doi.org/10.1177/030098589902700606

Publication

Veterinary pathology
ISSN: 0300-9858
NlmUniqueID: 0312020
Country: United States
Language: English
Volume: 27
Issue: 6
Pages: 419-425

Researcher Affiliations

Heinrichs, M
  • Institut für Veterinär-Pathologie, Justus-Liebig-Universität, Giessen, Federal Republic of Germany.
Baumgärtner, W
    Capen, C C

      MeSH Terms

      • Adenoma / chemistry
      • Adenoma / pathology
      • Adenoma / veterinary
      • Adrenocorticotropic Hormone / analysis
      • Animals
      • Female
      • Glial Fibrillary Acidic Protein / analysis
      • Horse Diseases / metabolism
      • Horse Diseases / pathology
      • Horses
      • Immunohistochemistry
      • Male
      • Peptides / analysis
      • Phosphopyruvate Hydratase / analysis
      • Pituitary Neoplasms / chemistry
      • Pituitary Neoplasms / pathology
      • Pituitary Neoplasms / veterinary
      • Pro-Opiomelanocortin / analysis
      • Prolactin / analysis
      • alpha-MSH / analysis
      • beta-Endorphin / analysis

      Citations

      This article has been cited 19 times.
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