Long-term effects of early social isolation in Macaca mulatta: changes in dopamine receptor function following apomorphine challenge.
The hypothesis that early social isolation results in long-term alterations in dopamine receptor sensitivity was tested using older adult rhesus monkeys. Isolated and control monkeys were challenged with apomorphine (0.1 and 0.3 mg/kg), and the drug effects on spontaneous blink rate, stereotyped behavior, and self-injurious behavior were quantified using observational measures. Monoamine metabolites were quantified from cisternal CSF by HPLC-EC, prior to pharmacological challenge. Isolated and control monkeys did not differ in CSF concentrations of HVA, 5-HIAA, or MHPG. At the higher dose, apomorphine significantly increased the rate of blinking, the occurrence of whole-body stereotypies, and the intensity of stereotyped behavior (as measured by observer ratings) in isolated monkeys. The frequency of occurrence of self-injurious behavior was too low to allow for meaningful comparisons. These significant differences in response to apomorphine challenge support the hypothesis that long-term or permanent alterations in dopamine receptor sensitivity, as assessed by drug challenge, are a consequence of early social deprivation.
Lewis
M H
MH
Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill 27599.
Gluck
J P
JP
Beauchamp
A J
AJ
Keresztury
M F
MF
Mailman
R B
RB
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001767:Blinking / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid; D008251:Macaca / Q000502:physiology*; D008253:Macaca mulatta / Q000502:physiology*; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D012931:Social Environment; D013239:Stereotyped Behavior / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D011954:Receptors, Dopamine; D006897:Hydroxyindoleacetic Acid; D001058:Apomorphine; D004298:Dopamine; D006719:Homovanillic Acid