Exp Toxic Pathol 1992; 44: 141-143 Gustav Fischer Verlag Jena

Short Communication

Institute of Pathological Anatomy, Friedrich Schiller University, lena, Germany

Morphom~tric

investigations on endocrine glands

VIII. Karyometry in epithelial cells of thyroid glands during inhibition of lactation by quinestrol O . Low and S. GRIMM With one table Received: September 13, 1990; Accepted: October 17, 1990

Address for correspondence: Dr. rer. nat. OTTO Low, Institut fUr Pathologische Anatomie "Robert Rossie", Friedrich-SchillerUniversitiit, Ziegelmiihlenweg 1, D - 0 - 6900 lena, Deutschland Key words: morphometry; karyometry; thyroid gland; lactation; quinestrol

Summary

A single dosis of 12.5 mg quinestrol per os post partum causes an inhibition of lactation in rats, which is accompanied by an moderate increase of the nuclear volume of the epithelial cells of the thyroid gland.

Introduction Mammary and thyroid glands are included in a complex endocrine interconnected control system. For a long time an enlargement of the human thyroid is known during gestation, and in many of such cases a return to normal in the first days post partum (FREUND 1882; review WEGELIN 1926). A new increase starting about a week after birth was not confirmed by other authors, but BERNARD (1927) observed a short inactivation stage between bearing and the following lactation period, and a higher activity in the thyroid during this time was also seen in groundsquirrels (ZALESKY 1935). The aim of the measurements was to study wether of not the thyroid is influenced by an inhibition of lactation.

Material and Methods Pregnant Wi star rats (Koloniezucht lenapharm lena) were maintained individually in plastic cages on sawdust at room temperature (21 ± 1.5°C). Food pellets and water were available ad libitum. The number of sucklings per female was standardized to 6 in the beginning, but the survival rate was different. 1 day post partum 6 control animals received 0.5 ml onicetan per os and always 6 animals per group were applied 12.5 mg quinestrol in 0.5 ml onicetan. After 7 or 15 days, respectively, the animals were sacrificed under ether anesthesia. The glands were fixed individually in 10 % formol for 7 days and embedded in par~ffin under standard conditions. Stage sections of about 5 [.tm were stained after V AN GIESON in the modification by VON BRZEZINSKY (1967, 1968) with naphthol red .

Karyometry of always 400 nuclei per organ was performed at a magnification of X 4,300. The longest diameter and in its middle the perpendicular one were measured in mm. The volume was calculated via the formula V = 3.14 . L . B . B . The mean values were estimated graphically in diagrams with the cumulative frequency distribution on the ordinate and the log volume on the abscissa, or by calculation, also with the original data. The mean values per group were ascertained with all single data per group (n = 2,400) or via the mean values per animal (n = 6).

Results After 7 days the quinestrol treated rats showed an enlargement in the thyroid nuclear volumes of about 10 %, one week later a further increase of 23 % was observed. There are no differences in the mean values estimated graphically or by calculation, but the statistical tests led to higher probability values, when n = 2,400 and the corresponding data are used . Skewness and kurtosis showed greater divergencies , when calculations are performed using the original data, compared with those after log-Transformation.

Discussion Beside other factors thyrotropic hormone, triiodothyronine and thyroxine maintain the lactation (reviews: SULMAN 1970; GOTZ and DOCKE 1981) . An increase of the thyroxine blood level in the latest gestation phase was found e.g. for cows , sows, goats and sheep and thyroxine may cause hyperthyreodism in cows associated with an enhanced elimination and a higher milk production (review SLEBODZINSKI 1981) , but SCHMIDT (1971) concluded that the administration of thyroid hormone seemed to be unsuccessful for cow droves in order to get a higher yield of milk. The suckling irritation causes, if any, only a slight change in the thyrotropin plasma concentration (SCHAMS 1976). STRBAK et al. (1978) found in lactating women during a period of 11 weeks a very small increase for this Exp. Toxic. Pathol. 44 (1992) 3

141

Table 1. Nuclear volume of epithelial cells in the thyroid gland of lactating rats with and without quinestrol. status

lactation

inhibited lactation

days

7 (I)

7 (II)

method

calc .

graph.

calc.

graph.

calc.

graph.

6 1.790 0.026

6 1.797 0.031

6 1.834 0.024

6 1.839 0.023

6 1.930 0.029

6 1.930 0.031

log-vol.

n x

s volume (!-tm)

x

log-vol.

n

61.8 3.7

s x

s sk k

62.7 4.4

2,400 1.790 0.137 -0.100 2.964

62 .7

61.7

vol. calc. volume (!-tm)

x

s sk k

2,400 1.797 0.130

64.8 20.6 0.913 4.752

68.3 3.7 2,400 1.834 0.142 -0.219 2.889 68.2

102.4

Morphometric investigations on endocrine glands. VIII. Karyometry in epithelial cells of thyroid glands during inhibition of lactation by quinestrol.

Exp Toxic Pathol 1992; 44: 141-143 Gustav Fischer Verlag Jena Short Communication Institute of Pathological Anatomy, Friedrich Schiller University,...
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