Hippocampal Lesions and Open-Field Defecation in Rats

Effects of dorsal and ventral hippocampal lesions on open-field defecation of rats were investigated. Based on presurgical testing, matched groups from both sexes were either lesioned or sham-operated. Compared to respective presurgical scores the postsurgical defecation score decreased significantly in the sham-operated group but remained the same in the hippocampally lesioned group. Results were discussed in terms of habituation and the inverted-U arousal function.

THYROID FUNCTION IN RATS SELECTIVELY BRED FOR EMOTIONAL ELIMINATION

SUMMARY 1. The effect has been studied of propylthiouracil, thyrotrophic hormone (TSH) and potassium iodide on the behaviour of rats from the Maudsley Reactive and Non-reactive strains bred for emotional defecation. 2. In Reactive, high defecating rats treated with propylthiouracil, the defecation scores increased significantly, and the ambulation score decreased slightly; in the Non-reactive, low defecating rats, no significant change occurred in the defecation score. 3. After the injection of TSH, the behavioural scores did not change significantly, although the defecation scores were decreased and the ambulation scores increased in the majority of cases. 4. No significant changes were found in response to the administration of potassium iodide. 5. Differences in adrenal weight were found between the two strains, the gland being significantly larger in the high defecating strain than in the low defecating one. 6. The ovaries of the high defecating females were significantly smaller than those of the low defecating ones. 7. No marked difference was found in the weight of the pituitary and testes. 8. The weight of the kidneys was significantly lower in the high defecating than in the low defecating strain. 9. Treatment with propylthiouracil and TSH altered the size of the thyroids, the serum protein bound iodine and the weight of the adrenals. Injections of pituitary extracts containing TSH also affected the weight of the kidneys.