PSYCHONEUROENDOCRINE PROFILE ASSOCIATED WITH HYPERTENSION OR HYPERACTIVITY IN SPONTANEOUSLY HYPERTENSIVE RATS

The behavioral and neuroendocrine reactivity to a novel environment (o pen field) and the adrenocorticotropic hormone (ACTH)/corticosterone r esponse to a corticotropin-releasing factor (CRF) challenge were measu red in 2-mo-old rats from four inbred strains derived from the Wistar- Kyoto rat: spontaneously hypertensive rats (SHRs), hypertensive and be haviorally hyperactive to novelty; WKY, neither hypertensive nor hyper active; WKHA, hyperactive but normotensive; and WKHT, only hypertensiv e. The ACTH response to CRF was much lower in SHRs than WKYs, this red uced reactivity being clearly associated with the hyperactivity trait, since it was present in the WKHA and absent in the WKHT strain. On th e other hand, the ACTH/corticosterone response to a psychological stim ulus (open field) could not clearly discriminate the four strains. The largest difference was found in the prolactin response. Post-open-fie ld levels were much lower in the WKHA (27.11 +/- 4.69 ng/ml) than in t he parent WKY strain (83.65 +/- 6.84 ng/ml), the hypertensive strains having intermediate levels (WKHT: 58.05 +/- 7.65 ng/ml; SHR: 64.13 +/- 7.19 ng/ml). Other differences were also found in the levels of aldos terone and renin activity. These results indicate that these strains a re an excellent model to study neuroendocrine correlates of hypertensi on and hyperactivity, which are associated in the SHR strain and may b e of interest for the study of the association between neuroendocrine and behavioral characteristics.