Tail Pinch Induces Fos Immunoreactivity Within Several Regions of the Male Rat Brain: Effects of Age
Section snippets
Animals and Stimulation
Male Long-Evans rats were obtained from Charles River Canada, St. Constant, Québec. Twelve young (2–3 months) and 12 middle-aged (12–13 months) males were used as subjects. The young males received at least 10 tests of sexual behavior prior to the experiment and were all sexually active. The middle-aged males had been used extensively as studs prior to the experiment but had ceased to show stable copulatory activity in the month preceding the experiment. Rats were housed in groups of two in
Results
All rats responded to the tail pinches by vocalization and turning towards the haemostatic forcep. After receiving one or two tail pinches, the rats in the five-pinch group would often vocalize as soon as their tail was touched by the forcep, and would attempt to escape immediately following a tail pinch. Some of these rats vocalized when picked up in their home cages prior to transportation to the stimulation chamber.
Fos immunoreactivity was obvious in several regions of the brain, most
Discussion
The present study demonstrates a significant effect of both age and number of stimulations in neural responsivity to tail pinch. A progressive and significant increase in Fos was observed in the PVN, PV-Thal, and VTA with greater amounts of tail pinch. The mPOA, MEA, and BLA also showed a progressive increase in Fos with greater amounts of tail pinch; however, this effect was significant only between zero and five pinches. An age effect was observed in the mPOA, PVN, PV-Thal, BLA, and VTA, such
Acknowledgements
This research was supported by grants from the Natural Sciences and Engineering Council of Canada (OGP-0138878) and Fonds pour la Formation de Chercheurs et l'Aide à la recherche du Québec (960-CE-103). We thank Drs. Yavin Shaham and Charles V. Mobbs for useful discussions.
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