Stress, appetite

CRH (Corticotropin releasing hormone) is expressed in the nucleus paraventricularis of the hypothalamus and drives the stress hormone system by activating synthesis and release of corticotropin at the pituitary and in turn corticosteroid from the adrenal cortex. CRH is also expressed at many other brain locations not involved in neuroendocrine regulation, e.g. the prefrontal cortex and the amygdala. Preclinical studies have shown that CRH also coordinates the behavioral adaptation to stress (e.g. anxiety, loss of appetite, decreased sleepiness, autonomic changes, loss of libido). 

The endogenous opioids are another family of peptides involved in different physiological processes including pain regulation, respiratory control, stress responses, appetite, thermoregulation, and humoral and cellular immune function (Bodnar RJ., 2008). Opioids act through their receptors, which are also members of the GPCR family, and are expressed in the central and peripheral nervous system as well as on cells of the immune system (Henriksen and Willoch 2008 Hauser... 

This model was developed after pioneering experiments carried out in the USA by Overmier and Seligman (1967) who reported profound behavioural changes in dogs after their exposure to inescapable, uncontrollable stress (footshock). Subsequent work has concentrated on rats and mice, which show a similar behavioural response. This is expressed as appetite and sleep disturbance, general passivity and, on re-exposure of subjects to the stress, a failure to attempt to escape ( escape deficits ), even when this is feasible. 

Appetite suppressant Suppression of stress-induced eating, starvation-induced eating, and spontaneous eating over a 10-h period in mice. " " ... 

The anorexia suffered by cancer patients is likely to arise from a combination of psychological stress, altered senses of taste and smell and increased levels of cytokines, which influence the appetite and satiety centres in the hypothalamus. There are several consequences micronutrient intake will be diminished and this may contribute to the signs and symptoms of the disease. Plasma amino acid levels will fall, as in starvation (Chapter 16). Synthesis of glutamine (by muscle, adipose and lung), aspartate (by liver), glutathione (by the intestine) and arginine (by the kidney) will all be compromised. The metabolic significance of all of these is discussed in Chapter 18. 

The 5-HTja receptor was first described in 1981 and is perhaps the best characterized of the serotonin receptors. 5-HTja receptors have been implicated in the regulation of aggression, affect, anxiety, appetite, sexual behavior, and in the control of stress-related disorders [Dourish et al. 1987]. Also, these receptors play a major role in modulating serotonergic transmission. 

To regulate the Stomach, treat nausea and poor appetite, especially under stress... 

It is true that people sometimes say they cannot remember their painful experiences but some people cannot stop remembering them, the curse of posttrauma tic stress disorder. The crucial factor in remembering appetites is probably the consequence of their free availability that I note above To remember them fully is to experience them and, possibly, to be drawn into the positively fed-back phase of their rewardingness. This creates an incentive for people to keep their aversive memories at a distance, perhaps entertaining them only in the form of factual correlates (Morley 1993). The inability to remember them may be like the inability to touch a sore similarly, the urge to remember them may be like the urge to touch a sore. The issue is not cognitive availability but motivation. 

However, some circumstances seem to expand the rewarding component of aversive appetites to the point at which they have the lure of addictions (that is, to the point at which they are not escaped or avoided even hours in advance) this can involve either entertaining forlorn wishes, for instance, until they foster pathological grief or paranoid jealousy, or succumbing to the urge to rehearse traumatic memories until they expand, via the Napalkov effect (Eysenck 1967) to become a posttrauma tic stress syn-... 

Stress and anxiety affect nicotine tolerance and dependence. The stress hormone corticosteroid reduces the effects of nicotine therefore, more nicotine is required to achieve the same effect. This increases tolerance to nicotine and leads to increased dependence. Animal studies have shown that stress can directly cause relapse of nicotine self-administration after a period of abstinence. Withdrawal symptoms of nicotine include irritability, impatience, hostility, anxiety, depressed mood, restlessness, increased appetite, and weight gain.2-4... 

A second study gave comparable results. Twelve AIDS patients were administered dronabinol, 5 mg twice a day [125], An improved appetite score was noted, body fat increased and symptom stress decreased. 

The slow phase of the stress system is characterized by processes that promote recovery from, and adaptation to, the stressful conditions that prompted the response. At the level of the hypothalamus, this phase is probably mediated by the urocortins acting through CRHR2 receptors (Reul and Holsboer, 2002 de Kloet et al., 2005). In contrast to the fast phase, the slow phase is associated w ith activation of the parasympathetic nervous system, w hich promotes the appetitive and metabolic functions, w hich help to restore homeostasis. As cortisol levels... 

Tonics are placebos. They may be defined as substances with which it is hoped to strengthen and increase the appetite of those so weakened by disease, misery, overindulgence in play or work, or by physical or mental inadequacy, that they cannot face the stresses of life. The essential feature of this weakness is the absence of any definite recognisable defect for which there is a known remedy. Since tonics are placebos, they must be harmless. ... 

In cattle, fluorosis can take the form of intermittent lameness (Figure 8.4) as well as stiffness and lesions of the bones and teeth. The clinical basis for the lameness is not well understood. Appetite is normally impaired and this may result in decreased weight gain, cachexia, and lowered milk yield. Decline in milk production may be secondary to appetite impairment or other responses. Evidence that animals may be suffering chronic F effect may be obtained from chemical analysis of the feed and elevated levels of F in urine and body tissues (Parker et al. 1979). Other effects include increased susceptibility to other environmental stresses and decrease in longevity. 

Stress can cause people to resort to cigarettes, drugs, alcohol, or sweets as they seek stimulants or depressants to numb the pain of it. We have already learned about the acidifying effects of these poor choices. The adrenal glands are taxed, and the high cortisol levels they release can stimulate the appetite. But consumption of sweets simply prompts greater production of cortisol. 

Apart from appetite improvement, AIDS patients have reported a number of other benefits from cannabis including reduction in nausea, reduced anxiety, relief of aches and pains, improved sleep, and inhibition of oral candidiasis (Grinspoon and Bakalar 1993 Plasse et al. 1991). Commonest reasons for smoking cannabis given in a recendy published survey (Sidney 2001) of Hl V-positive subjects were to feel better mentally or reduce stress (79%), improve appetite or gain weight (67%) and decrease nausea (66%). 

Weisinger RS, Blair-West JR, Bums P, Denton DA, McKinley MJ, Purcell B, et al. The inhibitory effect of hormones associated with stress on Na appetite of sheep. Proc Natl Acad Sci USA 2000 97 2922-2927. 

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