Reiter RJ, Reiter MN, Hattori A, Yaga K, Herbert DC, Barlow-Walden L. The pineal melatonin rhythm and its regulation by light in a subterranean rodent, the valley pocket gopher (Thomomys bottae).
J Pineal Res 1994;
16:145-53. [PMID:
7932037 DOI:
10.1111/j.1600-079x.1994.tb00094.x]
[Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The daytime and nightime levels of pineal N-acetyltransferase (NAT) activity, hydroxyindole-O-methyltransferase (HIOMT) activity, and melatonin were measured in adult male and female valley pocket gophers, Thomomys bottae. This species was chosen for study because it is a subterranean rodent that inhabits burrows whose openings to the surface are closed. Therefore, under field conditions it is estimated that the pocket gopher spends roughly 99% of its time in absolute darkness in underground burrows. When wild captured pocket gophers were maintained under a light:dark cycle (light intensity during the day of roughly 140 microW/cm2), nightime levels of pineal NAt activity and melatonin content were higher than values measured during the day; on the other hand, HIOMT activity in the pineal gland was similar in the day and at night. When pocket gophers were exposed to an extended light period (220 microW/cm2) 4 hr into the night, the rise in melatonin synthesis normally associated with darkness onset was not inhibited. Also, when gophers were acutely exposed to a light intensity of 400 microW/cm2 for 1 hr beginning 4 hr after darkness onset, neither high nocturnal levels of pineal NAT nor pineal melatonin contents were reduced. Finally, when pocket gophers were exposed to a 600 microW/cm2 light intensity at either 4 hr or 8 hr into the dark period, pineal melatonin synthesis remained elevated at a level comparable to that measured in dark-exposed controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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