Rhythmic dysfunctions in 11‐hydroxycorticoid excretion after midbrain lesions and their relationship to an abnormal grooming behavior in Cats∗∗∗

This research was supported by Grant MH‐15402 from the National Institute of Mental Health, United States Public Health Service.

Abstract

Cats with midbrain lesions exhibit a dissociation between appetitive and consummatory grooming behaviors that waxes and wanes with the seasons of the year. Because of various indications that the glucocorticoid hormones are involved in central nervous system functioning, and because the midbrain is implicated in the control and regulation of glucocorticoid hormones, and because of the prominent seasonal rhythm in glucocorticoid hormones, a measure of the urinary excretion of glucocorticoid hormones was obtained once a month for a year on normal and lesioned groups of cats. A quantitative measure of the grooming abnormality was obtained throughout the same year. A timing dysfunction in glucocorticoid excretion was found in the lesioned group: the normal group exhibited a prominent annual rhythm, but for the lesioned group a prominent four‐month rhythm was evident. The grooming abnormalities exhibited a prominent peak in the fall with minor fluctuations of about four‐month's duration. Because the individuals in a group were synchronized with regard to their rhythmic changes in glucocorticoid excretion, external events responsible for this synchrony were sought. The glucocorticoid rhythm of the normal group was correlated with solar radiation, whereas the lesioned group glucocorticoid rhythm was correlated with hours of sunshine. Another group of normal cats were adrenalectomized because of the apparent negative correlation between glucocorticoid excretion and the abnormal grooming behavior. And midbrain lesioned cats were injected with steroid hormones in an effort to abolish the abnormal grooming behaviors. Adrenalectomy had no influence on the grooming behaviors, but injection of glucocorticoids abolished the abnormal behavior. The implications of lesion‐induced changes in biological rhythms are discussed, and the fact that brain regulates hormones in order to provide for its own special milieu requirements is emphasized.

Abstracting keywords:

• Cats
• grooming
• hydroxycorticoid rhythms
• midbrain lesions

Notes

Dept of Psychology, Univ. of Iowa, Iowa City, Iowa 52240, U.S.A.

Univ. of Wisconsin at Parkside, Kenosha Campus, Natural Sciences, Kenosha, Wisconsin 53140, U.S.A.

This research was supported by Grant MH‐15402 from the National Institute of Mental Health, United States Public Health Service.