Naito H, Nakamura A, Inoue M
Department of Physiology II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan.
Exp Anim. 1998 Apr;47(2):89-96. doi: 10.1538/expanim.47.89.
The ontogenetic changes in responsiveness to benzodiazepine receptor ligands on ultrasonic vocalizations in rat pups from the age of day 3 to day 12 were evaluated. Rat pups, while separated from their dam and littermates and placed in a cold environment, emit ultrasonic vocalizations. These ultrasonic calls became attenuated dose-dependently in number and power after administration of the anxiolytic diazepam (0.25-1.0 mg/kg, s.c.), but the inhibitory effect of diazepam at the highest dose was less on day 6 and day 9. Moreover, type 1 benzodiazepine receptor ligands, Ro16-6028 and Ro23-0364 (0.5-2.0 mg/kg, s.c.), also dose-dependently attenuated the ultrasonic vocalizations 30-60 min after injection. The inhibitory effects of these drugs became more pronounced with the increasing age of the pup, and they were equivalent on day 12 to those in adult rats. These results suggest that different ontogenetic changes in development of two subtypes of central benzodiazepine receptors of pups might be related in the psychopharmacological mediation of the ultrasonic vocalization.
评估了出生3天至12天的大鼠幼崽对苯二氮䓬受体配体的反应性在超声发声方面的个体发生变化。大鼠幼崽在与母鼠和同窝幼崽分离并置于寒冷环境中时会发出超声叫声。给予抗焦虑药地西泮（0.25 - 1.0mg/kg，皮下注射）后，这些超声叫声的数量和强度呈剂量依赖性减弱，但地西泮在最高剂量时对第6天和第9天的抑制作用较小。此外，1型苯二氮䓬受体配体Ro16 - 6028和Ro23 - 0364（0.5 - 2.0mg/kg，皮下注射）在注射后30 - 60分钟也呈剂量依赖性减弱超声叫声。这些药物的抑制作用随着幼崽年龄的增加而更加明显，并且在第12天时与成年大鼠相当。这些结果表明，幼崽中枢苯二氮䓬受体两种亚型发育过程中不同的个体发生变化可能与超声发声的心理药理学调节有关。
