Somatic signs

Anxiety. Mental apprehension frequently accompanied by somatic signs such as increased heart rate, palpations, and increased muscle tension. 

Anxiolytic. A drug that decreases the mental symptoms and somatic signs of anxiety. 

In mice, somatic signs of withdrawal include wet dog shakes, front paw tremor, ataxia, hunched posture, tremor, ptosis, piloerection, mastication and decreased locomotor activity (Hutcheson et al. 1998). The CBl antagonist (SR141716A) has been used to precipitate a withdrawal state in THC-tolerant animals, and higher doses of THC produced a greater withdrawal syndrome (Aceto et al. 1995 Cook et al. 1998). Withdrawal from chronic cannabis use reduces mesolimbic dopaminer-... 

The methods discussed above have been widely used to assess the effect of either continuous or intermittent nicotine on nAChR functions and brain biochemistry (Matta et al. 2007). For models of nicotine withdrawal, see the chapter by Malin in this volume. Given the intrinsic advantages and limitations of each approach, the non-contingent nature of most administration regimes and the absence of associated cues, it is important that these paradigms are not assumed to model tobacco addiction per se. Sometimes, the experiments are conducted in concert with behavioural measures (e.g. precipitation of withdrawal with somatic signs), which give more credibility to the assertion that a state of nicotine dependence has been achieved (Kenny and Markou 2005). 

Injection of the opiate antagonist naloxone precipitates the somatic signs of nicotine withdrawal (Adams and Cicero 1998 Carboni et al. 2000 Malin et al. 1993a), but not affective signs, such as intracranial self-stimulation (ICSS) threshold elevation (Watkins et al. 2000). Yet naloxone injection in a nicotine-infused rat is robustly aversive (Ise et al. 2000 Watkins et al. 2000). Therefore, the somatic signs may actually correspond better than ICSS thresholds to an aversive motivational state. 

Naloxone precipitation, nnlike nicotine-antagonist challenge, fails to decrease DA-activity, yet still precipitates somatic signs (Carboni et al. 2000). Thus the aversiveness of nicotine withdrawal can be dissociated in part from those effects on the mesolimbic-DA reinforcement pathway that have sometimes been proposed to account for the affective aspects of withdrawal (Balfour 2004 Paterson et al. 2007). 

As described in Sect. 4, the somatic signs appear to depend a major extent on central nervons system mechanisms. 

While we realize that some others will disagree, we suggest that it cannot be automatically assumed that the somatic signs cannot reflect a centrally-mediated emotional or motivational state. For this reason, we refer to them not as somatic signs, but as somatically expressed behaviors. ... 

Lindblom N, de VUliers SH, Semenova S, Kalayanov G, Gordon S, Schilstrom B, Ohansson AM, Markou A, Svensson TH (2005) Active immunisation against nicotine blocks the reward facilitating effects of nicotine and partially prevents nicotine withdrawal in the rat as measured by dopamine output in the nucleus accumbens, brain reward thresholds and somatic signs. Naunyn Schmiedebergs Arch Pharmacol 372 182-194... 

Another important question is the relationship between nicotine abstinence and nicotine self-admiifistration. O Dell and Koob (2007) provided 23 h day access to intravenous nicotine self-administration for 4-day intervals with intervening 3-day intervals of nicotine abstinence. This resulted in somatically expressed behavioral signs as well as heightened nicotine self-administration on the first day following... 

Semenova S, Markou A (2003) Clozapine treatment attenuated somatic and affective signs of nicotine and amphetamine withdrawal in subsets of rats exhibiting hyposensitivity to the initial effects of clozapine, Biol Psychiatry 54 1249-1264 Semenova S, Bespalov A, Markou A (2003) Decreased prepulse inhibition during nicotine withdrawal in DBA/2J mice is reversed by nicotine self-administration. Eur J Pharmacol 472 99-110... 

Harris, Glenda C, and Gary Aston-Jones. 1993. "Beta-Adrenergic Antagonists Attenuate Somatic and Aversive Signs of Opiate Withdrawal." Neuropsychopharmacology 9 303-11. 

Gold AR, Dipalo F, Gold MS, O Heam D. Symptoms and signs of upper airway resistance syndrome a link to the functional somatic syndromes. Chest 2003. In press. 

PCP and ketamine produce detachment, disorientation, distortions of body image, and loss of proprioception. Somatic symptoms and signs include numbness, nystagmus, sweating, rapid heart rate, and hypertension. Overdosage has been fatal, as contrasted with the absence of known human fatalities directly caused by drugs of the LSD group. 

---