[Morphometric studies on the lateral habenular nucleus of Wistar rats after bilateral excision of the superior cervical ganglia and cold exposure with special reference to the pineal gland].
To analyse the role of peripheral sympathetic fibres in the regulation of thyroxine (T4), serum thyrotropin (TSH), pituitary TSH, and nuclear size of the lateral habenular nuclei rats were studied 30 d after bilateral cervical ganglionectomy (GX). In order to examine the influence of GX at normal temperature (24 degrees C) and exposure to cold (10 degrees C), rats were subjected to a 72 h exposure to cold before killing. 4 times a day (light-dark cycle: 14L: 10D, light on 05h00) the rats were sacrificed: middle light, middle darkness, 1 h after "light on" and 1 h after "light off". Ganglion removal resulted in a highly significant decrease of serum-T4 and increase of serum- and pituitary-TSH (primary hypothyroidism). Under these circumstances, the karyometric findings are showing a statistically significant magnification of the lateral habenular nuclear volume. In contrast to GX, exposure to cold increased T4- and TSH-levels and reduced the lateral habenular nuclear size. GX diminished the effect of exposure to cold of the T4- and TSH-levels and normalized the habenular nuclear volume. These results indicate that there exists a negative correlation between T4 (but not TSH) and lateral habenular nuclear size. Under consideration of previous investigations of the pineal nuclear size in hypo- and hyperthyroid state, our results are in agreement with the hypothesis of other authors that it is probably an inhibitory feed-back loop between the lateral habenula and the pineal gland (see also the high gamma-aminobutyric acid [GABA] content in the habenular complex). On the other hand, it was possible to confirm that the habenular complex is integrated into the thyroid circuit.
Tomalik
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Institut für Anatomie der Martin-Luther-Universität Halle, Wittenberg.
Peschke
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Peschke
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D000818:Animals; D005728:Ganglia, Sympathetic / Q000502:physiology*; D008297:Male; D010870:Pineal Gland / Q000502:physiology*; D010902:Pituitary Gland / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013788:Thalamus / Q000033:anatomy & histology* / Q000502:physiology; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism; D013974:Thyroxine / Q000097:blood
D013972:Thyrotropin; D013974:Thyroxine
Morphometrische Untersuchungen am Nucleus habenulae lateralis der Wistar-Ratte nach bilateraler Exstirpation der Ganglia cervicalia superiora und Kälteexposition unter besonderer Berücksichtigung der Epiphysis cerebri.