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Neonatal treatment with monosodium glutamate (MSG): structure
of the TSH-immunoreactive pituitary cells
B. Miskowiak1,2 and M. Partyka1
1Chair and Department of Histology and Embryology
and 2Chair of Optometry and Biology of Visual System, Karol Marcinkowski
University of Medical Sciences, Poznan, Poland
Offprint requests to:
Prof. Bogdan Mi´skowiak, Department of Histology and Embryology,
Karol Marcinkowski Unversity of Medical Sciences 6 ´Swiecicki
Str., 60-781 Pozna´n, Poland. e-mail: bmiskow@usoms.poznan.pl
Summary. Glutamic
acid represents the most abundant stimulatory neurotransmitter
in the central nervous system. Monosodium glutamate (MSG), subcutaneously
administered to newborn rats in the perinatal period, induces
lesions in 80 to 90% of the neurocytes of arcuate nuclei in the
hypothalamus. These nuclei are the site of production of numerous
stimulatory and inhibitory hormones including growth hormone releasing
hormone (GHRH).
The present studies were performed on male Wistar strain rats,
subcutaneously injected on days 2, 4, 6, 8, and 10 of postnatal
life with MSG at a dose of 4 mg/g body weight. Eighteen-month-old
rats were additionally treated with Ambinon. When the animals
reached the ages of 6 or 12 months, their body weight, body length
and weight of pituitary were determined. On paraffin sections,
using immunohistochemical techniques, TSH-immunoreactive cells
were detected and characterised by computerised image analysis.
The results were subjected to statistical analysis using Student's
t test.
The rats which were perinatally treated with MSG and examined
after 6 or 12 months of life were obese and shorter than control
rats by 7% and 10% respectively. They also exhibited a reduction
in the weight of the pituitary of 30% and 40% respectively in
the two age groups.
The proportion of TSH-immunoreactive cells in the pituitary remained
unchanged and amounted to 4.5% in the 6-month-old and 5.4% in
the 12-month-old rats, respectively. The number of TSH-positive
cells per mm2 area remained unchanged. The area and circumference
of the cells in the 12-month-old rats were reduced by 22% and
18%, respectively.
Perinatal injury to hypophyseal arcuate nuclei induced by monosodium
glutamate injection, was not associated with any significant alterations
in pituitary structure, as defined by the proportion of pituitary
volume occupied by TSH-immunoreactive cells. Histol. Histopathol.
15, 415-419 (2000)
Key words: MSG,
Pituitary, TSH-immunoreactive cells, Immunocytometry
DOI: 10.14670/HH-15.415
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