Spontaneous head twitches in aged rats: behavioral and molecular study

Area of Science:

• Neuroscience
• Pharmacology
• Aging Research

Background:

• A novel phenomenon, spontaneous head twitching (SHT), has been identified in 18-month-old rats.
• This age-related motor behavior has not been previously documented in scientific literature.

Purpose of the Study:

• To pharmacologically characterize spontaneous head twitching (SHT) in aging rats.
• To investigate potential underlying mechanisms of SHT, focusing on receptor interactions.

Main Methods:

• Wistar male rats aged 18 months were categorized into high (HSHT) and low (LSHT) spontaneous head twitching groups.
• Quantitative real-time PCR (TaqMan low-density array) was used to analyze gene expression in the hippocampus.

Main Results:

• Drugs targeting the 5-HT2A receptor, such as ketanserin, olanzapine, clozapine, risperidone, and pimavanserin, significantly affected SHT.
• DOI increased SHT, while ketanserin dose-dependently abolished it in HSHT rats.
• Antipsychotics acting primarily on dopamine receptors (haloperidol, amisulpride) and escitalopram did not influence SHT.

Conclusions:

• Spontaneous head twitching (SHT) emerges in approximately 50% of aging rats, exhibiting permanence and individual specificity.
• The 5-HT2A receptor plays a critical role in the regulation of SHT.
• Rats exhibiting high spontaneous head twitching (HSHT) represent a promising animal model for research on 5-HT2A receptor ligands.