Decrease of serotonin and metabolite in the forebrain and facilitation of lordosis by dorsal raphe nucleus lesions in male rats

Masaki Kakeyama, Asami Umino, Toru Nishikawa, Korehito Yamanouchi

Research output: Contribution to journalArticle

11 Citations (Scopus)


In castrated male rats, a radiofrequency lesion was made in the dorsal raphe nucleus (DRL) and lordosis behavior was observed following treatment with estrogen. After the behavioral test, brains were removed and the contents of 5-HT and 5-HIAA in the forebrain were measured by high pressure liquid chromatography (HPLC). In the results, only 2 of 16 control males without brain surgery showed lordosis, and the mean lordosis quotient (LQ) was extremely low when compared to that in control females. In contrast, all male rats with DRL displayed lordosis and the mean LQ was higher than that of control males without brain surgery but lower than that in control females (P<0.001). In the DRL males, 5-HT and 5-HIAA contents in the septum (SPT), the preoptic area (POA), the ventromedial hypothalamus (VMH) and the striatum (STM) were lower than those in control male and female groups (P<0.001). These results suggest that the dorsal raphe nucleus prevents male rats from showing lordosis by serotonergic influence in the forebrain. In addition, HPLC results showed that levels of the 5-HT in the SPT, the POA and the VMH in the female group were higher than those in the control male group (P<0.05). In female rats, the POA (P<0.01) and the VMH (P<0.05) contained larger 5-HT than those in the SPT and the STM, but there were no difference of 5-HT contents in the male rat.

Original languageEnglish
Pages (from-to)573-579
Number of pages7
JournalEndocrine Journal
Issue number5
Publication statusPublished - 2002 Oct 1



  • Dorsal raphe nucleus
  • Forbrain
  • Lordosis
  • Male rat
  • Serotonin

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Cite this