Raphe lesions and 5,7-dihydroxytryptamine induce grooming reflexes in adrenalectomized cats.

Abstract

Grooming reflexes are induced by frontal neocortical, pontile, or spinal lesions in dogs and cats. In intact cats, the combined treatments of adrenalectomy and para-chlorophenylalanine administration induce grooming reflexes. Two other ways of depleting serotonin (with 5,7-dihydroxytryptamine and raphe lesions) were combined with adrenalectomy in the present study as further tests that serotonin and glucocorticoid hormones are the critical factors in the induction of grooming reflexes. Because the deficit in serotonin is confined to the superior colhculi in cats with frontal and pontile lesions, 5,7-dihydroxytryptamine (5,7-DHT) was injected directly into the superior colhculi at eight sites, 2 ^g/site (1 ^1 at .5 /ul/min). Electrolytic dc lesions of the dorsal and superior central raphe nuclei were made in another group, and then both groups were adrenalectomized. There were three control groups (a) a group with vehicle injections in the superior colliculi and laporatomies, (b) a group with 5,7-DHT injections in the superior colliculi, and (c) a group with the raphe lesions. Large receptive fields for grooming reflexes occurred only in the groups with combined treatments. Thus the mechanism of induction of grooming reflexes by central nervous system lesions involves independent changes in a hormonal and a neurotransmitter system which combine to effect the change in beh?vior.

Increased mRNA for corticotrophin releasing hormone in the amygdala of Fawn‐hooded rats: A potential animal model of anxiety

“…In light of the vesicular serotonin storage deficit in Fawn-hooded rats, this strain may be a useful animal model for neurochemical abnormalities in obsessive-compulsive disorder in particular, an illness for whch there is evidence of serotonergic abnormalities , increased cerebrospinal fluid levels of CRH and A W (Altemus et al, 1992) and hypoactivity of the hypothalamic-pituitary-adrenal axis (Altemus et al, 1993). In cats, exaggerated grooming reflexes, which resemble grooming compulsions in humans w i t h obsessive-compulsive disor-der (OCD), can be induced by a combination of raphe lesions and adrenalectomy (Swenson and Randall, 1980). The combination of abnormalities found in the Fawn-hooded rat strain may resemble other anxiety disorders as well.…”

Mediation of the photoperiodic effect on grooming reflexes by glucocorticoid hormones and serotonin.

“…A parasagittal section was reconstructed through the plane of greatest destruction, and three frontal reconstructions through the area of the lesion were made. The histological verification of the sites of the 5,7-DHT injections has been presented previously, along with the neurochemical data on the serotonin reduction (Swenson & Randall, 1980).…”

“…The six cats receiving the sham adrenalectomy were subjected to the same procedure except for ligation and removal of the adrenals. The adrenalectomized cats received replacement therapy of 5 mg/ cat/month of a mineralocorticoid (desoxycorticosterone pivalate, a slowly absorbed preparation from CIBA Pharmaceutical Co.) to maintain electrolyte balance The dose of mineralocorticoid was determined from previous studies (e g., Swenson & Randall, 1980).…”

“…The cats were pretreated with desmethylimipramine hydrochloride (10 mg/kg of body weight) to minimize damage to catecholamine neurons by the 5,7-DHT. Complete details of the 5,7-DHT treatment have been presented (Swenson & Randall, 1980). The four remaining cats with pontile lesions served as the control group for the 5,7-DHT treatment; the pontile lesion provided the control for the 5,7-DHT treatment to the extent that all electrode and needle tracks were through the tectum and overlying cerebrum In summary, the four groups formed from the 19 cats with pontile lesions were as follows' pontile lesion plus adrenalectomy (n = 4), pontile lesion plus sham adrenalectomy (n = 6), pontile lesion plus 5,7-DHT (n = 5), and pontile lesion only (n = 4).…”

“…The seasonal changes in the size of the receptive field correlated negatively with the dysrhythmia in glucocorticoid excretion. The experimental manipulations suggested by these changes (serotonin depletion combined with adrenalectomy) induce grooming reflexes in normal cats (Randall, Elbin, & Swenson, 1974;Swenson & Randall, 1980). Although the photoperiodic effect need not necessarily be mediated by one of the factors involved in the induction of the abnormal behavior, their candidacy is recommended by the presence of seasonal rhythms in both.…”