EFFECTS OF PHOTOPERIOD-TEMPERATURE REGIMES AND 



PINEALECTOMY ON BODY FAT RESERVES IN 



THE GOLDEN SHINER, NOTEMIGONUS CRYSOLEUCAS 



Victor L. de Vlaming' 



ABSTRACT 



Various photoperiod-temperature regimes were examined for their effects on total fat content 

 (excluding gonads) in Notemigonus crysoleucas; experiments were conducted during several different 

 phases of the reproductive cycle. In Notemigonus, fattening normally occurs in fall and early winter 

 concomitant with the early phases of gonadal development. Body fat stores are progressively depleted 

 during the prespawning and spawning seasons. Warm temperature (25°C) normally favored body fat 

 depletion in Notemigonus. Short photoperiod (9L/15D) accentuated the lipid depleting effects of warm 

 temperatures. Low temperatures (12°-15°C) usually promoted lipid deposition. Short photoperiods 

 complimented the lipid anabolic effects of low temperatures. Thus, a given photoperiod can have 

 opposite effects on body fat levels depending on temperature. A long photoperiod, in combination with 

 warm temperatures, is required for final gonadal maturation and results in a reduction of lipid reserves. 

 Short photoperiod-warm temperature regimes have similar effects on fat levels, but bring about 

 gonadal regression. Thus, the effects of photoperiod-temperature regimes on lipid metabolism are 

 apparently not totally dependent on the effects of these environmental factors on reproduction. 



The effects of pinealectomy on lipid reserves varied depending on the phase of the natural 

 reproductive cycle when the organ was removed, as well as, with the photoperiod-temperature regime 

 under which the experimental animals were maintained. At 25°C and under a 15.5L/8.5D photoperiod, 

 fat levels were frequently lower in pinealectomized than in sham animals. The opposite was usually true 

 for fish exposed to a 9L/15D-25°C regime. Lipid reserves were normally greater in pinealectomized 

 than in sham operated fish maintained on 15.5L/8.5D-12°C regime. Body fat composition was 

 frequently less in pinealectomized than in sham operated animals exposed to a 9L/15D-12°C regime. 

 Pinealectomy reverses the effects of photoperiod on lipid metabolism at a particular temperature. 

 These results suggest that the pineal body is involved in regulating physiological functions and may 

 serve as a photoreceptor and/or transducer of photoperiod information. 



In most temperate-latitude aquatic environments 

 food availability varies seasonally and annual 

 cycles of growth, reproduction, and fattening are 

 normally observed in teleost fishes. Lipid reserves 

 may be used to meet the energy demands of 

 reproduction, and seasonal fattening cycles in 

 teleosts may be related to sexual cycling (Lovern 

 1934; Luhmann 1953; Love 1957; Idler and Bitners 

 1960; Woodhead 1960; Nikolsky 1963; Wilkins 1967; 

 Lasker 1970; de Vlaming 1971). Environmental 

 factors such as photoperiod and temperature are 

 used as cues to maintain annual reproductive 

 cycles in fishes (for reviews see de Vlaming 1972, 

 1974), but little is known about environmental 

 control of fattening. 



The pineal body of most fishes has sensory organ 

 characteristics (e.g., Riideberg 1966, 1969; Omura 

 and Oguri 1969; Owman and Riideberg 1970; 



'Biology Department, Marquette University, Milwaukee, WI 

 53233. 



Bergmann 1971; Oksche et al. 1971). Histological 

 examination of the pineal in various teleosts also 

 reveals secretory gland characteristics (e.g., 

 Takahashi 1969; Cheze and Lahaye 1969; Cheze 

 1970; Rizkalla 1970; Hafeez 1971). In mammals the 

 pineal appears to function as an endocrine gland 

 and the indolamine, melatonin, may be one of the 

 hormones of this organ (cf. Reiter 1973). His- 

 tochemical and biochemical data show that the 

 teleost pineal has an active indolamine me- 

 tabolism (Quay 1965; Hafeez and Quay 1969, 1970; 

 Fenwick 1970; Owman and Rudeberg 1970). Very 

 little, however, is known about the physiological 

 role of the pineal in teleost fishes. 



De Vlaming, Sage, Charlton, and Tiegs (1974) 

 showed that melatonin treatment results in body 

 lipid depletion in Fundulus similii^ and 

 Cyprinod/m variegatus acclimated to a long pho- 

 toperiod. In F. similis acclimated to a short pho- 

 toperiod during May, melatonin therapy also 

 resulted in fat depletion, but body fat deposition 



Manuscript accepted March 197.5. 



FISHERY BULLETIN; VOL. 73, NO. 4, 1975. 



766 



