Acute effects of light and darkness on the activity and temperature rhythms of a subterranean rodent, the Anillaco tuco-tuco

Author(s)

Yassumoto, I, Tamiris ; Tachinardi, Patricia ^[1] ; Oda, Gisele A. ^[1] ; Valentinuzzi, Veronica S. ^[2]

Affiliation

^[1] Yassumoto, Tamiris, I, Univ Sao Paulo, Inst Biociencias, Dept Fisiol, Lab Binatl Argentina Brasil Cronobiol, Sao Paulo, SP - Brazil

^[2] CRILAR CONICET, Ctr Reg Invest Cient & Transfer Tecnol La Rioja, Lab Binacl Argentina Brasil Cronobiol, Entre Rios & Mendoza S-N, RA-5301 Anillaco La Rioja - Argentina

• Document type: Journal article
• Source: Physiology & Behavior; v. 210, OCT 15 2019.
• Web of Science Citations: 0

Abstract

Tuco-tucos from Anillaco (Ctenomys aff. knights), are subterranean rodents that run vigorously on laboratory wheels during the night but are active during the day in semi-natural enclosures, where they surface for foraging and burrow maintenance, under intense sunlight. Several studies have shown that light causes opposite, inhibitory and stimulatory, ``masking{''} effects on the activity levels between nocturnal and diurnal species, respectively. Because of the alternating subterranean/surface activity of tuco-tucos in nature during the day and their ability to shift from diurnal to nocturnal patterns in field-to-lab transitions, we assessed the acute effects of light and darkness on running wheel activity, general activity and body temperature. Adult males and females were kept in a LD 12:12 h regimen and exposed to light and dark pulses to verify masking effects in their rhythms. A first experiment consisted in submitting animals to light pulses of different illuminance during the dark phase. Clear inhibition of wheel-running activity occurred, being the response more pronounced as illuminance of the pulse increased, a response typically seen in nocturnal rodents. A second experiment consisted in submitting animals to light pulses during the dark phase, and later to dark pulses during the light phase. This protocol occurred three times in the conditions: 1) without a wheel, 2) with free access to a wheel, and 3) with a blocked wheel. Wheel running was inhibited and body temperature decreased in most animals during the light pulse, with little to no inhibition on general activity. Dark pulses during the light phase had no effect on wheel running activity nor on general activity but did affect body temperature. Interestingly, there was a single individual that switched from nocturnal to diurnal when kept without a running wheel, offering an opportunity to test nocturnal and diurnal masking patterns to light in the same individual. (AU)

• FAPESP's process: 17/22973-1 - Investigation of seasonality and plasticity of daily activity patterns in a subterranean rodent (Ctenomys aff. knighti) using noninvasive methods of endocrine monitoring
• Grantee: Patricia Tachinardi Andrade Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 17/19680-2 - Photoperiodism in South American subterranean rodents under field and laboratory conditions
• Grantee: Gisele Akemi Oda
• Support Opportunities: Regular Research Grants