Prolonged 5-HT1A/5-HT2A receptor cross-talk is absent prior to adulthood in rats

In adult rats, serotonin 1A (5-HT1A) receptor activation produces heterologous desensitization of serotonin 2A (5-HT2A) neuroendocrine function at 1 h that persists up to 72 h. This study determined whether prolonged 5-HT1A/5-HT2A cross-talk exists before sexual maturation. Adolescent male rats (postnatal day 39) received an injection with saline or (+)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide [(+)8-OH-DPAT] 24 h before receiving a challenge injection of saline, (+)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide, or (-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl [(-)DOI] o assess changes in basal, 5-HT1A, and 5-HT2A receptor-mediated hormone responses. Although homologous desensitization of 5-HT1A neuroendocrine responses was present at 24 h, heterologous desensitization of 5-HT2A neuroendocrine responses was not. These data suggest that 5-HT1A heterologous desensitization of 5-HT2A receptor function does not develop until adulthood, is more transient, or follows a different time course before maturation.