Untitled

Abstract

The effects of two-day water deprivation and hyperhydration (provision of 4% sucrose solution for 48 h) on levels of serotonin and its major metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the midbrain and hypothalamus were studied in Wistar rats. The rates of diuresis (0.05 +/- 0.01 and 0.84 +/- 0.12 ml/h/100 g in water deprivation and hyperhydration respectively) and urine osmolality (1896 +/- 182 and 50 +/- 13 mOsm/kg) reflected increases and decreases in blood vasopressin levels. Water deprivation was associated with a significant increase in 5-HIAA levels in the midbrain and hypothalamus, along with a decrease in serotonin levels and a three-fold increase in serotonin catabolism (the 5-HIAA:serotonin concentration ratio). Hyperhydration induced moderate increases in serotonin and 5-HIAA levels in the hypothalamus with no changes in the midbrain. The blood corticosterone level doubled in water deprivation and decreased in hyperhydration. It is suggested that activation of the serotoninergic system induces a complex adaptive reaction in water deprivation. including mechanisms specific for the regulation of water-electrolyte homeostasis and non-specific stress mechanisms (vasopressin and corticoliberin secretion).

Blockade of the serotonin 5-ht2a receptor suppresses cue-evoked reinstatement of cocaine-seeking behavior in a rat self-administration model.

“…Food deprivation is associated with increased 5-HT turnover (Chaouloff et al, 1985; Tsujii et al, 1988; McBlane et al, 1994; Popova et al, 2001), increased cortical 5-HT 2A R density and increased functional responses to pharmacological stimulation of the 5-HT 2A R (Torda, Culman, Cechova, & Murgas 1988; Chaouloff, Baudrie, & Coupry 1994; Yamada, Watanabe, Nankai, & Toru 1995; Davis, Heal, & Stanford 1995; Stanford 1996; Matuszewich & Yamamoto 2003; Stamatakis & Hetherington 2003). Thus, under conditions that eliminate the possible influence of deprivation-induced changes in 5-HT function, we can confidently state that blockade of the 5-HT 2A R does not interfere with the reinforcing effects of cocaine and rule out the possible influence of food deprivation stress as an important independent variable in observed effects (Fletcher et al, 2002; Fantegrossi et al, 2002).…”

“…Serotonin systems, and the 5-HT 2A R in particular, are engaged under stressful circumstances (Chaouloff, Elghozi, Guezennec, & Laude 1985; Tsujii et al, 1988; McBlane & Handley 1994; Popova et al, 2001) and several methodological aspects of cocaine self-administration paradigms necessitate a consideration of suitable protocols to maximize interpretation of studies in which 5-HT 2A R ligands are investigated (Bongiovanni & See 2008). The procedures utilized for training of self-administration tasks in rodents typically involve food (or water) deprivation and a history of operant pretraining for a food (or water) reinforcer (Grottick, Fletcher, & Higgins 2000; Fletcher et al, 2002; Burmeister et al, 2004; Fletcher, Chintoh, Sinyard, & Higgins 2004; Filip 2005).…”

“…Initial operant pretraining for one appetitive reinforcer can influence subsequent behavior maintained by another reinforcer and can result in changes in response rates (Urbain, Poling, Millam, & Thompson 1978; Nader & Thompson 1989). Additionally, food deprivation is a typical feature of self-administration procedures and has been identified as a mild stressor to increase plasma corticosterone (Marinelli, Le Moal, & Piazza 1996; Takao, Nagatani, Kitamura, & Yamawaki 1997; Dallman et al, 1999), disrupt 5-HT function (Chaouloff et al, 1985; Tsujii et al, 1988; McBlane et al, 1994; Popova et al, 2001) and enhance psychostimulant-induced behavioral and neural responses (Carroll 1985; Carr 2007; Stamp, Mashoodh, van Kampen, & Robertson 2008). Thus, the design of self-administration studies without conditions of food deprivation and operant pretraining affords an opportunity to analyze serotonergic regulation of cocaine-seeking and –taking in rodents (Fletcher et al, 2002;, Neisewander & Acosta 2007; Fletcher et al, 2008; but, see Burbassi & Cervo 2008) under conditions that minimize the potential for associated stress-related confounds (Stanford 1996).…”

How ambient temperature affects mood: an ecological momentary assessment study in Switzerland

“…Drugs used to treat symptoms of anxiety, such as antidepressants or sedatives, can disrupt the thermoregulatory mechanisms in the body [ 33 , 36 ]. Dehydration, caused by sudden changes in temperature, can reduce serotonin levels and affect the pharmacokinetics of psychotropic drugs [ 33 , 37 , 38 ].…”

The association of ambient temperature with depression in middle-aged and elderly people: a multicenter prospective repeat survey study in China

“…Currently, the main possible mechanisms of temperature's effect on depression is as follows: low temperatures could influence the central nervous system and thus promote mental disorders, for example by affecting the structure of the central nervous system by affecting the function of the hippocampus [36]. Changes in ambient temperature can affect the regulation of serotonin, and serotonin imbalance may mediate the effect of temperature on depression [37]. In addition, temperature can also indirectly affect depression, such as, lower temperatures can lead to depression by affecting sleep [38,39].…”