Nulliparous female Syrian hamsters were used to investigate the effect of two different breeding systems on the fertility of the female Syrian hamster. We hypothesized that females submitted to a harem system (HS) would deliver smaller and more female-biased litters than in a monogamic system. Ten female and 10 adult male hamsters housed individually (G1) were kept in a monogamic temporary bree...

The regulation of the circadian rhythm is relayed from the central nervous system to the periphery by melatonin, a hormone synthesized at night in the pineal gland. Besides two melatonin G-coupled receptors, mt(1) and MT(2), the existence of a novel putative melatonin receptor, MT(3), was hypothesized from the observation of a binding site in both central and peripheral hamster tissues with an ...

Hamsters were trained to go left and right to sounds on their left and right sides, respectively. Silent trials were occasionally given in which no sound was presented. Hamsters exposed to a loud 2- or 10-kHz tone in 1 ear often shifted their responding on the silent trials to the side of the exposed ear, suggesting that they perceived a sound in that ear (i.e., tinnitus). The degree of tinnitu...

The responses of 2- and 8-day-old rats (Rattus norvegicus) and hamsters (Mesocricetus auratus) to thermal stimulation were assessed in 4 experiments. In Experiment 1, the surface underlying the pup was cooled, and the latency to escape to a region of warmth was measured. Experiment 2 required pups to locomote farther to gain access to warmth. Experiment 3 was similar to Experiment 1 except the ...