A. Fernandezguasti et C. Lopezrubalcava, ACTION OF IPSAPIRONE AND 8-OH-DPAT ON EXPLORATORY-BEHAVIOR IN HAMSTERS (MESOCRICETUS-AURATUS) - EFFECTS OF ANTAGONISTS AND P-CPA, Pharmacology, biochemistry and behavior, 50(3), 1995, pp. 375-382
The effect of the serotonergic drugs 8-OH-DPAT (0.0625, 0.125, and 0.2
5 mg/kg) and ipsapirone (5.0 and 10.0 mg/kg) on the exploratory behavi
or shown by hamsters under light : dark conditions was studied. These
drugs produced an increase in the number of transitions similar to tha
t induced by diazepam (0.25, 0.5, and 1.0 mg/kg), suggesting an anxiol
ytic action. The antagonists, methiotepin (0.31 mg/kg), pindolol (2.0
mg/kg), and alprenolol (5.0 mg/kg), did not modify the number of trans
itions per se and were partially effective in reverting ipsapirone's a
ction. Similarly, methiotepin and pindolol partially blocked 8-OH-DPAT
actions, whereas alprenolol lacked an effect. Drug-induced increases
in this behavior occurred despite the administration of p-CPA (400 mg/
kg X 3 days). The neurochemical analysis revealed that this treatment
decreased 5-HT levels (from 40% to 60%). Motor activity was assessed t
o control unspecific drug actions; 8-OH-DPAT produced an increase that
was effectively blocked by methiotepin, but was unaffected by pindolo
l, alprenolol, or p-CPA. These results suggest that the increase in th
e number of transitions produced by 8-OH-DPAT cannot be interpreted on
the basis of a reduced anxiety state. Data are discussed in terms of
the similarities and differences between the actions of 5-HT1A drugs i
n hamsters when compared with rats and mice.