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Impaired exploratory behaviour after DSP-4 treatment in rats: implications for the increased anxiety after
Abstract:
The effect of DSP-4, a neurotoxin selectively affecting the projections of the locus coeruleus, upon exploratory behaviour of rats was studied in a complex exploration test, including a choice between open and enclosed areas and both inquisitive and inspective exploration elements. One week after DSP-4 (50 mg/kg i.p.) administration, the neurotoxin-treated rats did not explore a novel open area to any extent on the first exposure to the apparatus; however, on the third day of testing, these animals began to explore the area and the novel objects. Diazepam (0.5 mg/kg) treatment did not change the behaviour of control rats, but significantly increased the exploratory activity of the DSP-4-treated animals. LY 288513, a selective CCKB receptor antagonist (0.01 mg/kg), prevented the increase in exploratory activity in the DSP-4-treated rats, but increased the exploratory activity of controls on the third exposure to the test situation. The results of this investigation suggest that DSP-4 treatment reduces neotic behaviour by increasing neophobia rather than by decreasing exploratory drive. The divergence reported between the relative potencies of CCKB receptor antagonists in exploratory activity and other anxiety tests may in part be due to the effects of these drugs on exploratory drive.
Insights
DSP-4 neurotoxin impairs exploratory behavior in rats by increasing neophobia. However, diazepam and CCKB receptor antagonists modulate this effect, suggesting complex interactions in anxiety and exploration.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
Background:
- The locus coeruleus plays a role in exploratory behavior and anxiety.
- DSP-4 is a neurotoxin that selectively targets noradrenergic neurons originating from the locus coeruleus.
Purpose of the Study:
- To investigate the effects of DSP-4 on exploratory behavior in rats.
- To examine the influence of diazepam and a CCKB receptor antagonist on DSP-4-induced behavioral changes.
Main Methods:
- Rats were administered DSP-4 (50 mg/kg) or saline.
- Exploratory behavior was assessed in a complex exploration test involving open/enclosed areas and novel objects.
- Rats received treatments with diazepam (0.5 mg/kg) or LY 288513 (0.01 mg/kg).
Main Results:
- DSP-4 treated rats showed reduced exploration of novel open areas and objects.
- Diazepam increased exploratory activity in DSP-4 treated rats.
- The CCKB receptor antagonist LY 288513 blocked the increase in exploratory activity in DSP-4 treated rats but increased it in controls.
Conclusions:
- DSP-4 treatment induces neophobia, reducing neotic behavior rather than exploratory drive.
- Modulation of exploratory activity by diazepam and CCKB receptor antagonists suggests complex interactions in neurotoxin-affected behavior.
- Discrepancies in CCKB antagonist potencies across different tests may relate to their effects on exploratory drive.