The anticonvulsant effect of saiga horn on febrile seizures by regulating brain serotonin content and inhibiting neuroinflammation

Ethnopharmacological relevance: Saiga antelope horn (SAH) is derived from the Saiga antelope (Saiga tatarica Linnaeus) of the bovidae family. SAH has been used for the treatment of febrile seizures (FS) in children for thousands of years in China. Due to the biological protection of Saiga antelope and its ethical reasons, the application of SAH has been widely restricted. Unfortunately, the field of artificial manufacturing of SAH is still blank at present. The mechanism of SAH in the treatment of FS is still unclear, which seriously hinders the further development of artificial antelope horns and the search for substitutes for SAH. At present, there is an urgent need to determine the mechanism of SAH in the treatment of FS, so as to provide a theoretical basis for artificial antelope horn and its substitutes.

Aim of the study: To explore the anti-FS effect of natural SAH on FS rat model and its possible mechanism, and to provide a theoretical basis for the subsequent manufacture of artificial antelope horns and the search for the best substitutes.

Materials and methods: FS was induced by a warm water bath (48 ± 0.5 °C). The latency and seizure grade of FS were observed and recorded. Hematoxylin-eosin (HE) staining was used to observe the functional defect of hippocampal cells. The contents of tryptophan (TRP), serotonin (5-HT), IL-1β and TNF-a in rat brain tissue were determined by ELISA. qRT-PCR and Western blot were used to detect the expression of 5-HT synthesis related neurotransmitter receptors, catalytic enzymes and inflammatory factors in hippocampus. Immunofluorescence was used to observe the expression of TPH2 protein in the dorsal raphe nucleus of rat brain.

Results: After pretreating rats with SAH, the seizure grade of FS was significantly reduced and the latency was prolonged. SAH can reduce the histological damage of hippocampal tissue induced by FS in rats. Further analysis of ELISA results showed that SAH significantly increased the levels of TRP and 5-HT in the brain of FS rats, and significantly decreased the levels of IL-1β and TNF-a. The results of QPCR showed that SAH could up-regulate the expression of ER-β and TPH2 mRNA and down-regulate the expression of IL-1β and TNF-ɑ mRNA in the hippocampus of rats. In addition, WB and immunofluorescence results showed that SAH could significantly up-regulate the expression of ER-β/TPH2/5-HT pathway in the hippocampus of FS rats and the expression of TPH2 protein in the raphe nucleus, but had no significant effect on SERT protein in the hippocampus of FS rats. In addition, ER-β protein inhibitor PHTPP significantly inhibited the therapeutic effect of SAH on FS rats.

Conclusions: The present study demonstrates that SAH has a significant anticonvulsant effect on the FS rat model. The mechanism may be related to the increase of TRP content and up-regulation the expression of ER-β/TPH2/5-HT signaling pathway in the brain of FS rats, thereby increasing the content of 5-HT in the brain and reducing the content of IL-1β and TNF-a in the brain.

 

Comments:

The findings of this study provide valuable insights into the potential mechanisms underlying the anticonvulsant effect of Saiga antelope horn (SAH) in the febrile seizures (FS) rat model. The results suggest that SAH treatment leads to several significant outcomes in the FS rat model:

1. **Reduction in Seizure Severity and Prolonged Latency:** SAH administration reduced the severity of seizures and extended the latency period, indicating its anticonvulsant properties.

2. **Histological Protection:** SAH protected against histological damage in the hippocampal tissue caused by FS, indicating a neuroprotective effect.

3. **Neurotransmitter Modulation:** SAH increased the levels of tryptophan (TRP) and serotonin (5-HT) in the brain. 5-HT is a neurotransmitter known to influence mood, emotion, and seizures. The increase in 5-HT levels could contribute to the anticonvulsant effect of SAH.

4. **Anti-inflammatory Effects:** SAH significantly decreased the levels of pro-inflammatory cytokines IL-1β and TNF-α in the brain. This anti-inflammatory effect might play a role in reducing neuronal hyperexcitability and preventing seizures.

5. **Gene Expression Changes:** SAH up-regulated the expression of ER-β (estrogen receptor beta) and TPH2 (tryptophan hydroxylase 2) mRNA. ER-β is involved in various physiological processes, including neuronal protection, and TPH2 is an enzyme crucial for serotonin synthesis. The up-regulation of these genes suggests a potential pathway through which SAH exerts its effects.

6. **Protein Expression Changes:** SAH significantly up-regulated the expression of ER-β, TPH2, and 5-HT in the hippocampus and TPH2 protein in the raphe nucleus. These changes further support the involvement of the ER-β/TPH2/5-HT signaling pathway in the anticonvulsant effect of SAH.

7. **Role of ER-β:** The study indicates that the therapeutic effect of SAH is, at least partially, mediated through the ER-β/TPH2/5-HT pathway, as the ER-β protein inhibitor PHTPP inhibited the therapeutic effect of SAH.

In summary, this study provides evidence that SAH possesses anticonvulsant properties in a rat model of febrile seizures. The mechanism appears to involve the modulation of neurotransmitter levels, anti-inflammatory effects, and the activation of the ER-β/TPH2/5-HT signaling pathway. Understanding these mechanisms is crucial for the potential development of SAH-based treatments for febrile seizures and may also contribute to the development of artificial antelope horns or suitable substitutes, reducing the reliance on the natural resource and addressing ethical concerns related to Saiga antelope protection.