Kubala Kenneth H, McGinnis Marilyn Y, Anderson George M, Lumia Augustus R
Texas State University, Department of Psychology, San Marcos, TX 78666, USA.
Brain Res. 2008 Sep 26;1232:21-9. doi: 10.1016/j.brainres.2008.07.065. Epub 2008 Jul 28.
The behavioral and neurochemical impact of low serotonin (5-HT) was examined in gonadally intact male rats exposed to an anabolic androgenic steroid (AAS) during puberty. Low 5-HT was induced beginning on postnatal day 26 using parachlorophylalanine (PCPA). Injections of the AAS, testosterone (TP), began on day 40. The rats were tested in both non-social (locomotor activity and nose poke for food) and social (low-threat and high-threat) contexts. PCPA and TP+PCPA significantly decreased locomotor activity. PCPA alone significantly increased nose poke latency compared to controls. Freezing in the PCPA group was significantly elevated compared to TP and TP+PCPA groups, but not compared to controls. AAS did not affect non-social behaviors. Thus, low serotonin may increase freezing in a non-social context. Following provocation, PCPA and TP+PCPA significantly increased aggression toward smaller non-threatening opponents, suggesting that males with low 5-HT are more aggressive in a low-threat context when provoked. In the resident-pair intruder test, TP significantly increased aggression whereas PCPA did not, suggesting that in a high-threat context, aggression is primarily mediated by AAS. TP+PCPA males were also significantly more aggressive in the high-threat context suggesting that exposure to AAS may override freezing behavior induced by low serotonin. Both PCPA and TP+PCPA significantly and substantially depleted 5-HT and 5-HIAA in all brain regions examined. AAS significantly decreased 5-HIAA levels in the hypothalamus and increased 5-HT levels in the frontal cortex. Following withdrawal from TP+PCPA, most behavioral and neurochemical measures returned to control levels. These data suggest that low serotonin may be a contributing factor in the increased aggression displayed by adolescents who abuse AAS.
在青春期接触合成代谢雄激素类固醇(AAS)的性腺完整雄性大鼠中,研究了低血清素(5-HT)对行为和神经化学的影响。从出生后第26天开始,使用对氯苯丙氨酸(PCPA)诱导低5-HT。从第40天开始注射AAS睾酮(TP)。在非社交(运动活动和觅食探鼻)和社交(低威胁和高威胁)情境中对大鼠进行测试。PCPA和TP+PCPA显著降低了运动活动。与对照组相比,单独使用PCPA显著增加了探鼻潜伏期。与TP组和TP+PCPA组相比,PCPA组的僵立显著升高,但与对照组相比没有差异。AAS不影响非社交行为。因此,低血清素可能会增加非社交情境中的僵立。受到挑衅后,PCPA和TP+PCPA显著增加了对较小无威胁对手的攻击性,这表明血清素水平低的雄性在受到挑衅时,在低威胁情境中更具攻击性。在常驻-配对入侵者测试中,TP显著增加了攻击性,而PCPA则没有,这表明在高威胁情境中,攻击性主要由AAS介导。TP+PCPA雄性在高威胁情境中也显著更具攻击性,这表明接触AAS可能会克服低血清素诱导的僵立行为。PCPA和TP+PCPA在所有检测的脑区中均显著且大量地消耗了5-HT和5-羟吲哚乙酸(5-HIAA)。AAS显著降低了下丘脑5-HIAA水平,并增加了额叶皮质5-HT水平。从TP+PCPA撤药后,大多数行为和神经化学指标恢复到对照水平。这些数据表明,低血清素可能是滥用AAS的青少年攻击性增加的一个促成因素。