Timing of progesterone and allopregnanolone effects in a serial forced swim test
Year: 2011
Type: article
Abstract: The forced swim test (FST) is commonly employed to test the potency of drugs to reduce immobility as an indicator of anti-despair. Certainly, antidepressant drugs reduce the total time of immobility and enlarge the latency to the first immobility period. FST is preceded by the open field test (OFT) to discard any influence of changes in general motor activity that could interfere with immobility in the FST. Albeit progesterone and its ¿a-reduced metabolite allopregnanolone produce antidepressant-like effects in the FST, the timing of actions is unknown. We hypothesized that the latency and duration of effects produced by progesterone and allopregnanolone may be characterized by repeated FST sessions; we therefore devised a serial-FST experimental design to evaluate the timing effects of these steroids on immobility, locomotion in the open field test, and grooming in the later as an indicator of response to stress. We included fifty-one ovariectomized adult Wistar rats weighing 200-250 g at the beginning of the experiments. They were ovariectomized by abdominal approach under anesthesia. Rats were housed six per cage, at room temperature (25 +- 1oC) under a 12 h/12 h light/dark cycle (lights ON at 7:00 a.m.) with ad libitum access to purified water and food. All of the experimental procedures followed National Institutes of Health Guidelines. The local Ethics Committee (Biomedical Research Institute, Universidad Nacional Autonoma de Mexico) approved the experimental protocol. A first group received vehicle (2-hidroxypropyl-¿Á-cyclodextrin dissolved in injectable sterilized water to obtain a 35% solution, control group n=17), the second group progesterone (1.0 mg/kg, n=17), and the third group allopregnanolone (1.0 mg/kg, n=17). All single injections were applied by intraperitoneal route at a volume of 0.8 ml/kg. The effects of treatments were evaluated in the serial-FST at 0.25, 0.5, 1, 2, 4, 6, and 24 h after injection, in a rectangular pool (height, 60 cm; length, 30 cm; width, 50 cm), with 24 cm deep water (25 ± 1ºC). We evaluated the total time of immobility, during 5 min, considered as the principal indicator of an anti-despair effect...
Language: English
Subfield: Pharmacology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W1945803091