General guidelines for use of wild mammal species are updated from the 1998 version approved by the American Society of Mammalogists (ASM) and expanded to include additional resources. Included are details on marking, housing, trapping, and collecting mammals. These guidelines cover current professional techniques and regulations involving mammals used in research. Institutional animal care and use committees, regulatory agencies, and investigators should review and approve procedures concerning use of vertebrates at any particular institution. These guidelines were prepared and approved by the ASM, whose collective expertise provides a broad and comprehensive understanding of the biology of nondomesticated mammals in their natural environments.

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Guidelines of the american society of mammalogists for the use of wild mammals in research

A review of central 5-HT receptors and their function

Mechanisms and functional implications of adult neurogenesis.

Stimulus-Transcription Coupling in the Nervous System: Involvement of the Inducible Proto-Oncogenes fos and jun

In mammals, circadian oscillators exist not only in the suprachiasmatic nucleus, which harbors the central pacemaker, but also in most peripheral tissues. It is believed that the SCN clock entrains the phase of peripheral clocks via chemical cues, such as rhythmically secreted hormones. Here we show that temporal feeding restriction under light–dark or dark–dark conditions can change the phase of circadian gene expression in peripheral cell types by up to 12 h while leaving the phase of cyclic gene expression in the SCN unaffected. Hence, changes in metabolism can lead to an uncoupling of peripheral oscillators from the central pacemaker. Sudden large changes in feeding time, similar to abrupt changes in the photoperiod, reset the phase of rhythmic gene expression gradually and are thus likely to act through a clock-dependent mechanism. Food-induced phase resetting proceeds faster in liver than in kidney, heart, or pancreas, but after 1 wk of daytime feeding, the phases of circadian gene expression are similar in all examined peripheral tissues.

/pdf/restricted-feeding-uncouples-circadian-oscillators-in-4f0e39fg6v.pdf

Restricted feeding uncouples circadian oscillators in peripheral tissues from the central pacemaker in the suprachiasmatic nucleus

Neural regulation of circadian rhythms.

Lighting cycles synchronize (entrain) mammalian circadian rhythms by altering activity of cells in the suprachiasmatic nucleus (SCN) of the hypothalamus, a circadian pacemaker. Exposure of hamsters and rats to light pulses at those phases of the circadian rhythm during which light can shift the rhythm caused increased immunoreactivity for the product of the immediate-early gene c-fos in cells in the region of the SCN that receives retinal fibers. Light pulses also increased messenger RNA for the Fos protein and for the immediate-early protein NGFI-A in the rat SCN. Similar increases in mRNA for NGFI-A were seen in the SCN of hamsters. Thus cells in this portion of the SCN undergo alterations in gene expression in response to retinal illumination, but only at times in the circadian cycle when light is capable of influencing entrainment.

http://science.sciencemag.org/content/sci/248/4960/1237.full.pdf

Light pulses that shift rhythms induce gene expression in the suprachiasmatic nucleus

1.

Neural mechanisms involved in the generation and entrainment of circadian rhythms of behaviour were studied in male golden hamsters,Mesocricetus auratus.




2.

Destruction of the suprachiasmatic nuclei (SCN) of the hypothalamus and accompanying interruption of the retino-hypothalamic tract (RHT) modified or eliminated entrainment to lighting cycles.




3.

Such lesions also prevented the generation of normal circadian rhythms of both activity and drinking. Some lesioned hamsters generated bimodal (circa 12 h) and trimodal (circa 8 h) activity patterns in constant conditions.




4.

Other lesioned hamsters appeared to be arrhythmic under constant conditions; power spectral analysis revealed low amplitude circa 8 h rhythms in the records of many of these hamsters.




5.

The records of many lesioned hamsters showed several activity components that dissociated from each other and from the illumination cycle and free ran independently for many cycles. These and other features of the activity records indicate that activity rhythms in hamsters are controlled by a complex of oscillatory units whose mutual coupling produces the features of normal circadian rhythmicity. The SCN are apparently responsible for the maintenance of normal coupling among these oscillators and, thereby, for the generation of circadian behavioural rhythmicity.




6.

The presence of residual entrainment after SCN destruction in some hamsters shows that visual pathways other than the RHT can to a limited extent mediate light effects on the circadian system.






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The role of the suprachiasmatic nuclei in the generation of circadian rhythms in the golden hamster, Mesocricetus auratus

Neuropeptide Y immunoreactivity in the hamster geniculo-suprachiasmatic tract.

We have investigated the effects of destruction of the geniculo-hypothalamic tract (GHT) on the circadian system of golden hamsters. In the first experiment, intact hamsters were housed in constant darkness, and phase shifts in running-wheel activity rhythms were assessed following 15-min light pulses administered at circadian time (CT) 12 (defined as the beginning of activity), CT 14, CT 18, and CT 20. Responses to light pulses at the same CTs were then reassessed after GHT lesions. Hamsters with complete lesions showed decreases in phase advances caused by light pulses at CT 18 and CT 20. Phase delays elicited by light at CT 12 and CT 14 were not altered. In a second study, intact and GHT-ablated hamsters housed in constant light received 6-hr dark pulses at various CTs. Hamsters with complete GHT ablation showed smaller advances than controls to dark pulses centered on CT 8-10. After 110 days in constant light, 7 of 10 intact hamsters showed splitting of their activity rhythms into two components, while only 1 of the 8 similarly treated ablated hamsters displayed dissociated activity components. Ablated hamsters had significantly shorter free-running periods during the first 35 days of exposure to constant light than did the intact hamsters. These results demonstrate that destruction of the GHT in the hamster alters phase shifting in response to periods of light or dark, and they indicate a role for the GHT in mediating several photic effects on the circadian system.

Benjamin Rusak

Papers

Neural regulation of circadian rhythms.

Light pulses that shift rhythms induce gene expression in the suprachiasmatic nucleus

The role of the suprachiasmatic nuclei in the generation of circadian rhythms in the golden hamster, Mesocricetus auratus

Neuropeptide Y immunoreactivity in the hamster geniculo-suprachiasmatic tract.

Lesions of the thalamic intergeniculate leaflet alter hamster circadian rhythms.