Naltrexone Alters Responses to Social and Physical Warmth: Implications for Social Bonding

Tristen K. Inagaki; Laura I. Hazlett; Carmen Andreescu


Soc Cogn Affect Neurosci. 2019;14(5):471-479. 

In This Article

Opioids and Physical Warmth

Opioids may also contribute to physical warmth, although current literature to support this hypothesis is sparse. In animals, opioids mediate changes in core body temperature (Clark, 1979; Adler et al., 1988) with opioid agonists injected into the lateral cerebral ventricle leading to an increase in core body temperature (Clark et al., 1983) and opioid antagonists decreasing body temperature (Handler et al., 1992). Similarly, in humans, exogenously administered opiates alter correlates of thermoregulatory function (Martin et al., 1973; Kurz et al., 1995). As reviewed above, physically warm experiences led to increases in feelings of social connection. Therefore, we expect opioids to alter the effect of physical warmth on feelings of social connection. That is, opioids might further affect social connection by increasing felt social connection when experiencing physical warmth.

In the only study to examine the contribution of opioids to physical-warmth-induced feelings of social connection, participants took naltrexone and placebo before evaluating warm and cool stimuli (Inagaki et al., 2015). As expected, holding a warm (vs cool) object increased feelings of social connection. Naltrexone, however, specifically reduced feelings of social connection to holding the warm but not the cool object. Thus, it is plausible that opioids similarly contribute to social and physical warmth. However, whether opioids affect neural activity to both social and physical warmth and the potential link between the two experiences is currently unknown.