BEHAVIORAL MEASURES OF ANXIETY DURING OPIATE WITHDRAWAL

Heightened anxiety is a major component of the withdrawal syndromes as sociated with ethanol and sedative hypnotic medications. Because of si milarities between the opiate and sedative-hypnotic withdrawal syndrom es as well as data implicating heightened noradrenergic tone with opia te withdrawal, we investigated changes in anxiety measures identified by plus-maze and social interaction testing during opiate withdrawal. Because Sprague Dawley rats had very low levels of entry into plus-maz e open arms, further studies were conducted using the Long-Evans strai n. Long-Evans rats received continuous infusions of morphine sulfate a t 44 mg/kg per day delivered by osmotic pump over 7 days while control animals received inert implants. During the first 3 days of withdrawa l, the number and time of entries into open and closed arms of a plus- maze was recorded. Both social and aggressive behaviors were scored du ring pairings of groups of two socially naive animals. Body weight was significantly reduced in morphine-treated animals prior to and during withdrawal. Both the number of entries into open plus-maze arms and t he time spent in open areas increased over the 3 days of testing. Howe ver, no difference in plus-maze activity was detected between morphine -treated and control subjects. On the third day of withdrawal, social interaction time was greater in pairs of withdrawn and control subject s compared to pairs of two control subjects. In conclusion, behavioral measures of anxiety are not increased during opiate withdrawal.