Comp. Biochem PhysioL Vol. 71C, No. 2. pp 209 to 213, 1982 0306-4492/82/020209-05503.00/0 Printed in Great Britain. © 1982 Pergamon Press Ltd ANALYSIS OF MONOAMINE ACCUMULATIONS IN THE NEURONAL TISSUES OF MYTILUS EDULIS AND ANODONTA CYGNEA (BIVALVIA)--III. TEMPERATURE AND SEASONAL INFLUENCES LASZLO HIRIPI l, DONNA E. BURRELL 2, MARITZA BROWN 2, PAUL ASSANAH 2, ANNA STANEC 3 and GEORGE B. STEFANO 2'3'* ~Biological Research Institute, Hungarian Academy of Science, Tihany, Hungary; 2Department of Natural Sciences, Medgar Evers College, C.U.N.Y., 1150 Carroll Street, Brooklyn, NY 11225, U.S.A.; and 3St Joseph's Hospital and Medical Center, 703 Main St, Patterson, NJ 07503, U.S.A. (Received 23 June 1981) Abstract 1. The high affinity uptake component exhibits enhanced affinity for 5-HT at 0'~C. 2. The total amount of monoamine accumulated at 0°C is reduced. 3. 3-chlorimiprimine inhibited 5-HT uptake (IDso value of 0.21 x 10 6 M) and benztropine inhibited DA uptake (IDso value of 0.08 × 10 6 M) at lower concentrations at 0"C than reported for 24°C. 4. The pedal ganglion of M. edulis was found to exhibit seasonal variations in regard to the affinity of the uptake1 process and the amount of monoamine accumulation. 5. The uptake1 component appears to exhibit seasonal variations in regard to K + sensitivity being more sensitive to K + during warmer months. INTRODUCTION The effects of environmental temperature on mono- amine metabolism in various regions of the mam- malian CNS has been the subject of numerous reports. Norepinephrine (NE) and dopamine (DA) levels in rats increase in response to cold stress (Leduc, 1961), whereas serotonin (5-HT) synthesis in- creases in response to heat (Reid et al., 1968). These relationships also have been found to occur in various ectotherms (Wilhoft & Quay, 1965; Harri, 1972a,b). Despite the widespread occurrence of NE, DA and 5-HT in invertebrates and their roles as putative hor- mones and neurotransmitters, little is known about the consequences of temperature induced changes on the neuronal accumulation of the various mono- amines. In invertebrates, changes in monoamine levels can occur in a relatively short time period in response to temperature stress (Stefano et al., 1977). Levels of 5-HT have been found to increase both as a response to heat acclimation in the heart of A. cygnea (Lager- spetz & Tirri, 1968) and as a response to short term heat stress in the CNS and gill of M. edulis (Stefano & Catapane, 1978). In M. edulis changes in the activity and synthesis of tryptophan hydroxylase are involved in the response of 5-HT metabolism to temperature stress (Stefano & Catapane, 1977a). In another report it was demonstrated that 5-HT in both A. cygnea and M. edulis increased in response to heat stress and de- creased in response to cold stress whereas DA and NE displayed transient cyclic changes for both treat- ments (Stefano et al., 1978). M. edulis exhibits a diurnal rhythm of lateral ciliary activity which corresponds to environmental tempera- * Address reprint requests to GB.S. ture changes (Stefano et al., 1977). This rhythm can be modified by treating the animals with serotonergic and dopaminergic agents, thus demonstrating that manifestation of this temperature dependent rhythmi- city is due to monoaminergic pathways. It has also been found that levels of 5-HT, DA and NE in the CNS of M. edulis exhibit seasonal changes. Higher levels occurring in warmer months and lower levels occurring in colder months (Stefano & Catapane, 1977b). It is clear from these studies that it would be important to determine the effect of temperature on the monoamine accumulation processes since they represent the primary mechanism for monoamine ac- tivity termination in M. edulis. MATERIAL AND METHODS Specimens of M. edulis were collected from the shores of Long Island Sound at Northport, N.Y. The animals were collected at a depth of 8 ft by utilizing scuba diving tech- niques. The fresh water mussel A. cygnea was collected from Lake Balaton in the vicinity of the Biological Research Institute, Tihany. All animals used for these ex- periments were of the same shell lengths, 3 cm for M. edulis and 10cm for A. cygnea. M. edulis not used for the seasonal studies were maintained at O'C for 30 days in aer- ated aquaria containing seawater filtered through cheese cloth. Microscopic inspection of the water revealed the presence of various organisms which served as a food source. The seawater was changed every other day with fresh aerated seawater at O'C. The random inspection of the water removed from the aquaria after this time period revealed that fewer potential food organisms were present (subjective). A. o'gnea were maintained in filtered aerated water from Lake Balaton at either 24 or 0°C for 30 days. At the time of collection, animals to be used for the seasonal stndies were collected and maintained with water obtained at the same depth as the organisms. The delay between the time of collection to the time of isotope incu- bation was approximately 2 hr, during which time the ani- 209