Changes in hypothalamic catecholamines and serotonin during hibernation and arousal in the arctic ground squirrel

Hypothalamic monoamines and their metabolites in the deermouse,Peromyscus maniculatus, during daily torpor

“…The activity of tryptophan hydroxylase, the rate-limiting enzyme for 5-HT synthesis, was also significantly increased during the hibernating state in the woodchuck (Young et al, 1979). Although some investigators have reported decreased (Canguilhem et al, 1977) or unchanged (Feist and Galster, 1974;Weekley and Harlow, 1987) brain 5-HT levels during hibernation, this indole is considered to be involved in the control of the entry and maintenance phases of hibernation (Canguilhem et al, 1986).…”

“…However, the turnover rates of NE and EP were found to be markedly depressed or completely inhibited in hibernating hedgehogs (Sauerbier and Lemmer, 1977) and ground squirrels (Draskoczy and Lyman, 1967). Moreover, hypothalamic NE levels were depressed during hibernation in woodchucks (Young et al, 1979) and arctic ground squirrels (Feist and Galster, 1974). These results have been generally interpreted to indicate that the catecholamines, in particular NE, do not play an active role in the entry and maintenance phases of hibernation.…”

“…The role of the hypothalamic monoamines in the regulation of the hibernating state has been investigated in a variety of species. The concentration of hypothalamic norepinephrine (NE) was found to be significantly reduced in the hibernating woodchuck (Young et al, 1979) and arctic ground squirrel (Feist and Galster, 1974). However, no significant reductions in levels of NE were reported for the hibernating European hamster (Canguilhem et al, 1977).…”

“…Data on the functional state of the hypothalamic serotonergic system during hibernation is somewhat contradictory. Investigators have found depressed (Canguilhem et al, 1977), static (Young et al, 1979;Feist and Galster, 1974), and elevated (Popova and Voitenko, 1981;Oeltgen et al, 1986) serotonin (5-HT) levels during hibernation. Moreover, the status of the hypothalamic dopaminergic system during hibernation has not been extensively studied, although Oeltgen et al (1986) reported that dopamine (DA) and homovanillic acid (HVA) levels remained unchanged in the hibernating thirteen-lined ground squirrel.…”

Hypothalamic monoamines and their metabolites in the deermouse,Peromyscus maniculatus, during daily torpor

“…The activity of tryptophan hydroxylase, the rate-limiting enzyme for 5-HT synthesis, was also significantly increased during the hibernating state in the woodchuck (Young et al, 1979). Although some investigators have reported decreased (Canguilhem et al, 1977) or unchanged (Feist and Galster, 1974;Weekley and Harlow, 1987) brain 5-HT levels during hibernation, this indole is considered to be involved in the control of the entry and maintenance phases of hibernation (Canguilhem et al, 1986).…”

“…However, the turnover rates of NE and EP were found to be markedly depressed or completely inhibited in hibernating hedgehogs (Sauerbier and Lemmer, 1977) and ground squirrels (Draskoczy and Lyman, 1967). Moreover, hypothalamic NE levels were depressed during hibernation in woodchucks (Young et al, 1979) and arctic ground squirrels (Feist and Galster, 1974). These results have been generally interpreted to indicate that the catecholamines, in particular NE, do not play an active role in the entry and maintenance phases of hibernation.…”

“…The role of the hypothalamic monoamines in the regulation of the hibernating state has been investigated in a variety of species. The concentration of hypothalamic norepinephrine (NE) was found to be significantly reduced in the hibernating woodchuck (Young et al, 1979) and arctic ground squirrel (Feist and Galster, 1974). However, no significant reductions in levels of NE were reported for the hibernating European hamster (Canguilhem et al, 1977).…”

“…Data on the functional state of the hypothalamic serotonergic system during hibernation is somewhat contradictory. Investigators have found depressed (Canguilhem et al, 1977), static (Young et al, 1979;Feist and Galster, 1974), and elevated (Popova and Voitenko, 1981;Oeltgen et al, 1986) serotonin (5-HT) levels during hibernation. Moreover, the status of the hypothalamic dopaminergic system during hibernation has not been extensively studied, although Oeltgen et al (1986) reported that dopamine (DA) and homovanillic acid (HVA) levels remained unchanged in the hibernating thirteen-lined ground squirrel.…”

Hypothalamic monoamines and their metabolites in the deermouse,Peromyscus maniculatus, during daily torpor

“…The activity of tryptophan hydroxylase, the rate-limiting enzyme for 5-HT synthesis, was also significantly increased during the hibernating state in the woodchuck (Young et al, 1979). Although some investigators have reported decreased (Canguilhem et al, 1977) or unchanged (Feist and Galster, 1974;Weekley and Harlow, 1987) brain 5-HT levels during hibernation, this indole is considered to be involved in the control of the entry and maintenance phases of hibernation (Canguilhem et al, 1986).…”

“…However, the turnover rates of NE and EP were found to be markedly depressed or completely inhibited in hibernating hedgehogs (Sauerbier and Lemmer, 1977) and ground squirrels (Draskoczy and Lyman, 1967). Moreover, hypothalamic NE levels were depressed during hibernation in woodchucks (Young et al, 1979) and arctic ground squirrels (Feist and Galster, 1974). These results have been generally interpreted to indicate that the catecholamines, in particular NE, do not play an active role in the entry and maintenance phases of hibernation.…”

“…The role of the hypothalamic monoamines in the regulation of the hibernating state has been investigated in a variety of species. The concentration of hypothalamic norepinephrine (NE) was found to be significantly reduced in the hibernating woodchuck (Young et al, 1979) and arctic ground squirrel (Feist and Galster, 1974). However, no significant reductions in levels of NE were reported for the hibernating European hamster (Canguilhem et al, 1977).…”

“…Data on the functional state of the hypothalamic serotonergic system during hibernation is somewhat contradictory. Investigators have found depressed (Canguilhem et al, 1977), static (Young et al, 1979;Feist and Galster, 1974), and elevated (Popova and Voitenko, 1981;Oeltgen et al, 1986) serotonin (5-HT) levels during hibernation. Moreover, the status of the hypothalamic dopaminergic system during hibernation has not been extensively studied, although Oeltgen et al (1986) reported that dopamine (DA) and homovanillic acid (HVA) levels remained unchanged in the hibernating thirteen-lined ground squirrel.…”

Hypothalamic monoamines and their metabolites in the deermouse,Peromyscus maniculatus, during daily torpor

“…The activity of tryptophan hydroxylase, the rate-limiting enzyme for 5-HT synthesis, was also significantly increased during the hibernating state in the woodchuck (Young et al, 1979). Although some investigators have reported decreased (Canguilhem et al, 1977) or unchanged (Feist and Galster, 1974;Weekley and Harlow, 1987) brain 5-HT levels during hibernation, this indole is considered to be involved in the control of the entry and maintenance phases of hibernation (Canguilhem et al, 1986).…”

“…However, the turnover rates of NE and EP were found to be markedly depressed or completely inhibited in hibernating hedgehogs (Sauerbier and Lemmer, 1977) and ground squirrels (Draskoczy and Lyman, 1967). Moreover, hypothalamic NE levels were depressed during hibernation in woodchucks (Young et al, 1979) and arctic ground squirrels (Feist and Galster, 1974). These results have been generally interpreted to indicate that the catecholamines, in particular NE, do not play an active role in the entry and maintenance phases of hibernation.…”

“…The role of the hypothalamic monoamines in the regulation of the hibernating state has been investigated in a variety of species. The concentration of hypothalamic norepinephrine (NE) was found to be significantly reduced in the hibernating woodchuck (Young et al, 1979) and arctic ground squirrel (Feist and Galster, 1974). However, no significant reductions in levels of NE were reported for the hibernating European hamster (Canguilhem et al, 1977).…”

“…Data on the functional state of the hypothalamic serotonergic system during hibernation is somewhat contradictory. Investigators have found depressed (Canguilhem et al, 1977), static (Young et al, 1979;Feist and Galster, 1974), and elevated (Popova and Voitenko, 1981;Oeltgen et al, 1986) serotonin (5-HT) levels during hibernation. Moreover, the status of the hypothalamic dopaminergic system during hibernation has not been extensively studied, although Oeltgen et al (1986) reported that dopamine (DA) and homovanillic acid (HVA) levels remained unchanged in the hibernating thirteen-lined ground squirrel.…”