Brain temperature and its role in physiology and pathophysiology: Lessons from 20 years of thermorecording

Abstract

It is well known that temperature affects the dynamics of all physicochemical processes governing neural activity. It is also known that the brain has high levels of metabolic activity, and all energy used for brain metabolism is finally transformed into heat. However, the issue of brain temperature as a factor reflecting neural activity and affecting various neural functions remains in the shadow and is usually ignored by most physiologists and neuroscientists. Data presented in this review demonstrate that brain temperature is not stable, showing relatively large fluctuations (2-4°C) within the normal physiological and behavioral continuum. I consider the mechanisms underlying these fluctuations and discuss brain thermorecording as an important tool to assess basic changes in neural activity associated with different natural (sexual, drinking, eating) and drug-induced motivated behaviors. I also consider how naturally occurring changes in brain temperature affect neural activity, various homeostatic parameters, and the structural integrity of brain cells as well as the results of neurochemical evaluations conducted in awake animals. While physiological hyperthermia appears to be adaptive, enhancing the efficiency of neural functions, under specific environmental conditions and following exposure to certain psychoactive drugs, brain temperature could exceed its upper limits, resulting in multiple brain abnormalities and life-threatening health complications.

Worsening of the Toxic Effects of (±)Cis-4,4′-DMAR Following Its Co-Administration with (±)Trans-4,4′-DMAR: Neuro-Behavioural, Physiological, Immunohistochemical and Metabolic Studies in Mice

“…One of the main physiological alterations caused by (±)cis-4,4 -DMAR was here hyperthermia. Psychostimulants may induce both hyperthermic and hypothermic responses in rodents depending on environmental temperature, psycho-physiological activation (stressinduced hyperthermia), drug pharmacodynamics, social interactions and gender [50][51][52]. In our experimental conditions (room temperature 22-23 • C), (±)cis-4,4 -DMAR induced hyperthermia, consistent with observations made with remaining synthetic stimulants such as MDMA, methamphetamine, cocaine, methylone, MDPV, α-PVP, PMMA and MDAI [30,50,[53][54][55][56][57][58][59][60].…”

A low-cost mouse cage warming system provides improved intra-ischemic and post-ischemic body temperature control – application for reducing variability in experimental stroke studies

“…Brain temperature is influenced by multiple local factors (such as brain metabolic activity and blood flow), it can therefore differ in absolute temperature compared with core temperature or temporalis muscle temperature (DeBow and Colbourne, 2003;Jackson-Friedman et al, 1997;. However, in non-stimulated conscious rodents, brain temperature generally parallels core temperature (DeBow and Colbourne, 2003;Kiyatkin, 2019Kiyatkin, , 2010, thus allowing body temperature measurements to be used as a reasonable approximation of brain temperature.…”

In Vitro and In Vivo Pharmaco-Toxicological Characterization of 1-Cyclohexyl-x-methoxybenzene Derivatives in Mice: Comparison with Tramadol and PCP

“…The hypothermia induced by tramadol was partially prevented by naloxone, suggesting that other mechanisms come into play in the thermoregulation exerted by tramadol. Indeed, tramadol modulates the release of both NE and 5HT, either of which are directly involved in thermoregulation mechanisms [ 53 ]. On the other hand, PCP showed no significant alterations in body temperature in the 3 h after the injection, as reported by [ 54 ].…”