A further characterization of alpha-2 adrenoceptor involvement in the rough-and-tumble play of juvenile rats

• Published in: Developmental psychobiology 2000-07, Vol.37 (1), p.25-34
• Main Authors: Siviy, Stephen M., Baliko, Christopher N.
• Format: Article
• Language: English
• Subjects: Adrenergic alpha-Agonists - pharmacology; Adrenergic alpha-Antagonists - pharmacology; adrenoceptors; alpha-2; Animals; Behavior, Animal - drug effects; Clonidine - pharmacology; development; Idazoxan - analogs & derivatives; Idazoxan - pharmacology; juvenile; Male; norepinephrine; Norepinephrine - physiology; Play and Playthings; play-fighting; Rats; Rats, Sprague-Dawley - physiology; Receptors, Adrenergic, alpha-2 - drug effects; Receptors, Adrenergic, alpha-2 - physiology
• ISSN: 0012-1630; 1098-2302
• DOI: 10.1002/1098-2302(200007)37:1<25::AID-DEV4>3.0.CO;2-C

In order to further understand the extent to which alpha‐2 adrenoceptors are involved in play behavior, a more detailed behavioral assessment was made of the effects of the alpha‐2 agonist clonidine and the alpha‐2 antagonist RX821002 on the rough‐and‐tumble play of juvenile rats. Clonidine reduced overall levels of playfulness, as indicated by fewer attacks directed to the nape, a lower probability of rotating completely to supine in response to nape attacks and fewer pins. In contrast, RX821002 increased playfulness, as indicated by more attacks directed to the nape, a higher probability of rotating completely to supine in response to nape attacks and more pins. Testing rats in an unfamiliar environment did not affect the ability of RX821002 to increase play. Abruptly turning on a bright light during an ongoing play session also did not affect the ability of RX821002 to increase play or the ability of clonidine to reduce play. These data suggest that alpha‐2 noradrenergic compounds do not affect play by altering levels of distractibility. However, the extent to which RX821002 and clonidine influenced overall activity during a play bout was compromised by turning on a bright light. While this pattern of results is consistent with a presynaptic site of action for alpha‐2 involvement in modulating overall activity during a play bout, the same cannot be concluded about any putative explanatory mechanism for alpha‐2 involvement in play behavior. © 2000 John Wiley & Sons, Inc. Dev Psychobiol 37: 25–34, 2000