Table 2.
Feeding and body weight phenotypes of 5-HTR knockout mice
| Receptor | Feeding & body weight phenotypes of mutant animals | Additional comments | References |
|---|---|---|---|
| 5-HT1A | Increased intake of sucrose solution in females (potentially sex-hormone related). No alterations in homecage feeding or body weight reported. | Increased anxiety related behaviours and reduced depression-related behaviours | Heisler et al. (1998); Parks et al. (1998); Ramboz et al. (1998); Bechtholt et al. (2008) |
| 5-HT1B | Mildly increased body weight and relative increase in food intake | Reduced sensitivity to d-fen and mCPP induced hypophagia. Compensatory reduction in 5HT2CR function | Lucas et al. (1998); Bouwknecht et al. (2001); Clifton et al. (2003); Lee et al. (2004) |
| 5-HT2A | No alterations in homecage feeding, novelty suppressed feeding or body weight reported. | Increased anxiety related behaviours | Weisstaub et al. (2006) |
| 5-HT2B | Not reported | Mutants died perinatally due to incomplete heart development | Nebigil et al. (2000) |
| 5-HT2C | Marked hyperphagia throughout life and increased body weight gain from around 12 weeks | Increased locomotor activity and subsequent age-dependent reductions in energy cost of physical activity. Dysregulation of HPA axis and reduced anxiety-related behaviour | Tecott et al. (1995); Nonogaki et al. (2003); Heisler et al. (2007a,b) |
| 5-HT3 | No observed differences in body weight or food intake | Dysregulation of the HPA axis in response to stress | Bhatnagar et al. (2004) |
| 5-HT4 | Modestly reduced weight gain in homecage environment, despite normal food intake. Food intake increased after restraint induced stress | This model of stress induced anorexia has been associated with an increase in CART expression | Compan et al. (2004); Jean et al. (2007) |
| 5-HT5 | Normal body weight. No data on food intake reported | Increased exploratory behaviour that was independent of an effect on anxiety | Grailhe et al. (1999) |
| 5-HT6 | Normal body weight. No data on food intake reported | Altered responses to ethanol | Bonasera et al. (2006) |
| 5-HT7 | Normal body weight. No data on food intake reported | Failed to exhibit the expected hypothermic response to serotonin administration | Hedlund et al. (2003) |
Abbreviations: d-fen, dexfenfluramine; HPA, Hypothalamic-Pituitary-Adrenal; CART; cocaine and amphetamine regulated transcript.