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Chronic administration of 5-HT1A receptor agonist relieves depression and depression-induced hypoalgesia.

Jiang ZC, Qi WJ, Wang JY, Luo F - ScientificWorldJournal (2014)

Bottom Line: Previous studies have shown that depressed patients as well as animal models of depression exhibit decreased sensitivity to evoked pain stimuli, and serotonin is indicated to be involved in depression-induced hypoalgesia.The depression-like behavior and pain thresholds were measured using open-field test and radiant heat thermal pain test, respectively.In contrast, chronic administration of 8-OH-DPAT reduced locomotor activity and pain thresholds and restored them to normal level.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China ; University of Chinese Academy of Sciences, Beijing 100039, China.

ABSTRACT
Previous studies have shown that depressed patients as well as animal models of depression exhibit decreased sensitivity to evoked pain stimuli, and serotonin is indicated to be involved in depression-induced hypoalgesia. The purpose of this study was to investigate the potential role of 5-HT1A receptor in the depression-induced hypoalgesia. Acute or chronic administration of 5-HT1A receptor agonist, 8-OH-DPAT, was performed in olfactory bulbectomy (OB) and sham-operated rats. The depression-like behavior and pain thresholds were measured using open-field test and radiant heat thermal pain test, respectively. We found that acute administration of 8-OH-DPAT increased locomotor activity and pain thresholds in the sham rats but had no effect on the OB rats. In contrast, chronic administration of 8-OH-DPAT reduced locomotor activity and pain thresholds and restored them to normal level. Increased pain thresholds were also observed in the sham rats after the chronic administration. These results demonstrated that chronic administration of 8-OH-DPAT reversed the depression-induced decrease in pain sensitivity in rats, suggesting that 5-HT1A receptor may play a role in the depression-associated hypoalgesia.

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Related in: MedlinePlus

Effects of chronic administration of 8-OH-DPAT. (a) Locomotor activity in the open-field. Chronic 8-OH-DPAT treatment had no effect on the sham rats but significantly reduced the locomotor activity in the OB rats (n = 8–12). (b) Radiant heat pain threshold. Pain thresholds in the sham rats were increased after the treatment; by contrast, those in the OB rats were decreased and restored to normal level (n = 8–12). Data are presented as mean ± SEM. *P < 0.05, ***P < 0.001.
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fig4: Effects of chronic administration of 8-OH-DPAT. (a) Locomotor activity in the open-field. Chronic 8-OH-DPAT treatment had no effect on the sham rats but significantly reduced the locomotor activity in the OB rats (n = 8–12). (b) Radiant heat pain threshold. Pain thresholds in the sham rats were increased after the treatment; by contrast, those in the OB rats were decreased and restored to normal level (n = 8–12). Data are presented as mean ± SEM. *P < 0.05, ***P < 0.001.

Mentions: As shown in Figure 4, chronic 8-OH-DPAT treatment had no effect on the sham-treated rats, while significantly reducing the locomotor activity in the OB rats (two-way ANOVA, 3568 ± 438 versus 6425 ± 275 cm, P < 0.001), contrary to the observation of acute administration (Figure 4(a)). Thermal pain threshold test revealed significantly prolonged PWLs in the sham-operated rats after chronic 8-OH-DPAT treatment (two-way ANOVA, 11.04  ±  0.83 versus 7.16 ± 0.37 s, P < 0.001), consistent with that observed in the acute administration. However, after chronic 8-OH-DPAT treatment, the PWLs in the OB rats were significantly reduced (two-way ANOVA, 9.76 ± 0.66 s versus 7.62 ± 0.83 s, P < 0.05) and restored to normal level (OB/8-OH-DPAT versus Sham/saline: two-way ANOVA, 7.62 ± 0.83 versus 7.16 ± 0.37 s, P > 0.05) (Figure 4(b)). These results suggest that chronic 8-OH-DPAT treatment relieves the depression-like behavior and OB-induced hypoalgesia in rats.


Chronic administration of 5-HT1A receptor agonist relieves depression and depression-induced hypoalgesia.

Jiang ZC, Qi WJ, Wang JY, Luo F - ScientificWorldJournal (2014)

Effects of chronic administration of 8-OH-DPAT. (a) Locomotor activity in the open-field. Chronic 8-OH-DPAT treatment had no effect on the sham rats but significantly reduced the locomotor activity in the OB rats (n = 8–12). (b) Radiant heat pain threshold. Pain thresholds in the sham rats were increased after the treatment; by contrast, those in the OB rats were decreased and restored to normal level (n = 8–12). Data are presented as mean ± SEM. *P < 0.05, ***P < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3921963&req=5

fig4: Effects of chronic administration of 8-OH-DPAT. (a) Locomotor activity in the open-field. Chronic 8-OH-DPAT treatment had no effect on the sham rats but significantly reduced the locomotor activity in the OB rats (n = 8–12). (b) Radiant heat pain threshold. Pain thresholds in the sham rats were increased after the treatment; by contrast, those in the OB rats were decreased and restored to normal level (n = 8–12). Data are presented as mean ± SEM. *P < 0.05, ***P < 0.001.
Mentions: As shown in Figure 4, chronic 8-OH-DPAT treatment had no effect on the sham-treated rats, while significantly reducing the locomotor activity in the OB rats (two-way ANOVA, 3568 ± 438 versus 6425 ± 275 cm, P < 0.001), contrary to the observation of acute administration (Figure 4(a)). Thermal pain threshold test revealed significantly prolonged PWLs in the sham-operated rats after chronic 8-OH-DPAT treatment (two-way ANOVA, 11.04  ±  0.83 versus 7.16 ± 0.37 s, P < 0.001), consistent with that observed in the acute administration. However, after chronic 8-OH-DPAT treatment, the PWLs in the OB rats were significantly reduced (two-way ANOVA, 9.76 ± 0.66 s versus 7.62 ± 0.83 s, P < 0.05) and restored to normal level (OB/8-OH-DPAT versus Sham/saline: two-way ANOVA, 7.62 ± 0.83 versus 7.16 ± 0.37 s, P > 0.05) (Figure 4(b)). These results suggest that chronic 8-OH-DPAT treatment relieves the depression-like behavior and OB-induced hypoalgesia in rats.

Bottom Line: Previous studies have shown that depressed patients as well as animal models of depression exhibit decreased sensitivity to evoked pain stimuli, and serotonin is indicated to be involved in depression-induced hypoalgesia.The depression-like behavior and pain thresholds were measured using open-field test and radiant heat thermal pain test, respectively.In contrast, chronic administration of 8-OH-DPAT reduced locomotor activity and pain thresholds and restored them to normal level.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China ; University of Chinese Academy of Sciences, Beijing 100039, China.

ABSTRACT
Previous studies have shown that depressed patients as well as animal models of depression exhibit decreased sensitivity to evoked pain stimuli, and serotonin is indicated to be involved in depression-induced hypoalgesia. The purpose of this study was to investigate the potential role of 5-HT1A receptor in the depression-induced hypoalgesia. Acute or chronic administration of 5-HT1A receptor agonist, 8-OH-DPAT, was performed in olfactory bulbectomy (OB) and sham-operated rats. The depression-like behavior and pain thresholds were measured using open-field test and radiant heat thermal pain test, respectively. We found that acute administration of 8-OH-DPAT increased locomotor activity and pain thresholds in the sham rats but had no effect on the OB rats. In contrast, chronic administration of 8-OH-DPAT reduced locomotor activity and pain thresholds and restored them to normal level. Increased pain thresholds were also observed in the sham rats after the chronic administration. These results demonstrated that chronic administration of 8-OH-DPAT reversed the depression-induced decrease in pain sensitivity in rats, suggesting that 5-HT1A receptor may play a role in the depression-associated hypoalgesia.

Show MeSH
Related in: MedlinePlus