The pineal complex in Roman high avoidance and Roman low avoidance rats

Abstract

Previous studies have shown that the pineal gland of Roman high avoidance (RHA/Verh) rats is larger than that of Roman low avoidance rats (RLA/Verh). In the present study measurement of enzyme activities (serotonin-N-acetyl-transferase, hydroxyindole-O-methyltransferase) revealed that pineals of RHA/Verh rats are twice as active in melatonin production than pineals of RLA/Verh rats. Indoleamine content was also higher in RHA/Verh rats, whereas noradrenaline content was the same in both lines. When values were expressed per mg protein, these differences disappeared except for N-acetyl-serotonin and noradrenaline which were higher or lower in RHA/Verh rats, respectively. Both lines had higher serum levels of melatonin during the dark phase than during the light phase. However, RHA/Verh rats had increased serum levels as compared to RLA/Verh rats during both day and night. Morphometric analysis of the deep and superficial part of the pineal complex revealed, that the volumes of both parts are enlarged in RHA/Verh rats. Electron microscopic studies of pineals collected during day- and nighttime showed higher numbers of synaptic ribbons per unit area in pineals of RHA/Verh rats. In pineals collected during June synaptic ribbons displayed a day/night rhythm in RHA/Verh rats only, whereas in glands of both lines collected during November no daily changes were found. These results show that closely related but divergently selected rat lines may differ in pineal ultrastructure and pineal function.

Neurobehavioral and neurodevelopmental profiles of a heuristic genetic model of differential schizophrenia- and addiction-relevant features: The RHA vs. RLA rats

“…RHA rats are sensation/novelty seeker rats and, similar to what had been observed in novelty seeker cats and humans, RHA rats (compared with RLA and Wistar control rats) are cortical-evoked-potential augmenters Siegel 1997;Siegel et al, 1993 (see also Saxton et al, 1987a,b) Mainz and Magdeburg, Germany / Schwegler, Yilmazer-Hanke, Seidel Schwegler et al, 1997;Yilmazer-Hanke et al, 2002, 2016 (i)-Studies of differences in the amygdala and associations with fear-and anxiety-related responses provides evidence that the amygdala of RLA rats is more functional than that of their RHA counterparts (ii)-The pineals of RHA rats are twice as active in melatonin production than those of RLA rats, and the pineal gland is also larger in RHA rats, also exhibiting an increased density of pineal synaptic ribbons Seidel et al, 1990 (see also Requintina et al, 1994) Cagliari, Italy / Giorgi, Corda, Quartu, Serra, Sanna Corda et al, 1997Corda et al, , 2005Corda et al, , 2014Fattore et al, 2009;Giorgi et al, 1994Giorgi et al, , 1997Giorgi et al, , 2005aGiorgi et al, -b, 2007Giorgi et al, , 2015Lecca et al, 2004;Piras et al, 2003;Rosas et al, 2018 Supplementary Table 1 (continued) (i)-First demonstration that RHA rats are more sensitive to the acute and chronic (i.e. sensitization) effects of drugs of abuse, are more vulnerable to drug addiction, and have a more functional mesolimbic dopaminergic system (ii)-RHA rats display higher sexual motivation and sexual activity than do RLA and SD rats.…”

Individual variation in the (patho)physiology of energy balance

“…This seems to be caused by differences in the biological clock since Rivest and colleagues found that the pineal of the RHAs was twice the size of the glands of the RLA rats [44]. This difference at the level of the pineal gland leads to increased secretion of melatonin in the RHA rats [45] and significant changes in sleep patterns and the organization of sleep [46]. We also looked at the circadian rhythmicity meal patterns, in both the Roman and the WTG strain ( Fig.…”

Pinealocyte synaptic ribbons and neuroendocrine function

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