Behavioral effects of betacarbolines in pigs:. anxiety or aversion?

Betacarbolines are often considered to be anxiogenic and may, therefore, have similar behavioral effects to those of corticotrophin releasing hormone (CRH); however, their actions have been little studied in pigs. This investigation was concerned with the effects of ethyl-beta-carboline-3-carboxylate (BCCE) and noreleagnine (NOR) on operant feeding, cortisol release, and overt behavior in swine, all of which are known to be affected by CRH in this species. Three experiments are described in which BCCE or NOR were given intravenously to prepubertal boars (n = 7). In Experiment 1, 400 microg/kg, but not 100 or 200 microg/kg, BCCE produced a rapid inhibition of ingestive activity whereas NOR (100, 200, or 400 microg/kg) was without effect. In Experiment 2, both BCCE and NOR increased plasma cortisol, but not growth hormone, concentrations. In Experiment 3, a high dose of BCCE (2 mg/kg) produced transient arousal and a sustained increase in respiration rate and plasma cortisol. These results indicate that although the responses of pigs to BCCE and CRH are similar in some respects, there are also marked behavioral differences. The possibility that BCCE has aversive rather than anxiogenic actions in this species is discussed.