Alphonse Riesenfeld

Growth-Depressing Effects of Alcohol and Nicotine in Two Strains of Rats

Inbred Buffalo and Fisher rats were submitted to daily treatment with alcohol and nicotine for a period of 6 months. Alcohol treatment was pre- and postnatal, nicotine treatment postnatal only. All parameters of bone length and weight were depressed in both experiments in spite of the continuous growth of the rats. Although the level of depression was greater in some areas than in others, a clear target area applicable to both sexes and strains could not be found. Fisher and Buffalo females tolerated nicotine better than males. Buffalo rats showed a greater tolerance to alcohol than Fisher rats, and males tolerated alcohol better than females. This was particularly evident in pregnant rats: whereas all alcohol-treated Fisher embryos were stillborn, some of their Buffalo counterparts survived. This is most likely due to the lesser bone robusticity of Fisher over Buffalo rats and resorption of the fetal bones in Fisher embryos resulting from the decalcifying effect of alcohol.

Age Changes of Bone Size and Mass in Two Strains of Senescent Rats

6-month-old Buffalo and Fisher inbred rats were compared with their respective senescent counterparts. It appeared that length as well as weight of the various sections of the skeleton increased into old age. However, in some skeletal parts, length increase was greater than weight increase, so that relative robusticity of those parts, relating weight to length, dropped. The two different strains of rats showed differences in age-related bone reactions. Thus, while in humans, age-related bone loss is absolute, in rodents it is relative in certain sections of the body, or does not occur at all, but strain-dependent differences in rats have some parallels in human breeding populations.

Effects of Nicotine on the Fertility, Cytology and Life Span of Male Rats

Contrary to an earlier opinion that nicotine has no effect on the fertility of male animals or humans, the present experimental study using male inbred Fisher rats demonstrates that the reproductive capacity of the animals is greatly reduced when injected with nicotine, and that the effect is much greater in male than in female Fisher rats similarly injected with nicotine. This is in accord with some earlier histological and morphological studies which have shown that female rodents have a greater tolerance to nicotine than their male counterparts. It is also confirmed by the cytologic observations of the present study. These observations show that, similar to female rats, inflammatory processes, as evidenced by an increased number of lymphocytes and/or polymorphonuclear leukocytes, are responsible for the decrease in fertility. However, the cytological profile is profoundly different in the two sexes: virulent inflammatory conditions begin much earlier in male rats, they are more frequent and, whereas the condition is reversible in the female animal when nicotine treatment is discontinued, it is not in some male rats, and inflammatory conditions persist for the entire life as does infertility. However, the life span of nicotine-treated male rats is greater than in female nicotine-treated rats, although it is shorter in both sexes than in their respective controls; in some male nicotine-treated rats, the life span is greater not only than in their male controls but even than in their female counterparts. Possible explanations for this apparently paradoxical life-prolonging effect of nicotine treatment are reviewed, but the evidence is either conflicting or insufficiently established and requires further study.

Metatarsal robusticity in primates and a few other plantigrade mammals

By using a new technique for determining relative metatarsal robusticity, the distribution of the 1+5 pattern (in which M5 is the second most robust metatarsal after M1) and 1→5 pattern (in which M5 is the least robust of all metatarsals) was established in primates and a few other plantigrade mammals. The first pattern is associated with a terrestrial and the second with an arboreal substrate. Robusticity formulae are not connected with specific locomotor patterns, but a total robusticity quotient is associated with these patterns and substrate preference as well. Changes in substrate preference are accompanied by changes of total robusticity, an increased number of permutations and ultimately a change of the robusticity pattern. Intermetatarsal robusticity gradients are related to the direction and intensity of muscular activity. A combined analysis of all factors can reveal a great deal of the locomotor history of a taxon.

Endocrine control of skeletal robusticity

Changes of skeletal robusticity result from a mosaic response of various parts of the skeleton to given endocrine changes. The character of these reactions corresponds to that of muscles which act as selective target areas for specific hormones. Robusticity changes are mediated by increases or decreases of the length and weight of the bones. The changes are probably species- or even subspecies-specific.

Sexual dimorphism of bone robusticity in different strains of rats.

A quantitative method was used to establish the sexual dimorphism of bone robusticity in 10 domesticated strains of rats and in wild rats. Sexual dimorphism had its highest frequency in the pelvis, followed by the ulna, the skull, and the femur and tibia. Humerus and tail showed the lowest frequency of such sexual dimorphism. This distribution in an unspecialized mammal such as the rat, in which selective pressures are at their minimum becauses of the factor of domestication, can serve as a baseline for comparison with taxa in which selective forces are more strongly active.

Vibrissae removal and the phenomenon of unexplained sudden death.

Two earlier theories on the effect of vibrissae removal in rats were tested. One theory stating that vibrissae removal produces impairment of spatial orientation capacity was confirmed. The other stating that it causes a depressive state of hopelessness and sudden death could not be confirmed. It is concluded that the extrapolation from the particular animal experiment to human psychological processes is not justified.

Sexual dimorphism of skeletal robusticity in several mammalian orders

This study tries to determine whether a phylogenetic trend exists in the sexual dimorphism of skeletal robusticity and whether domestication has an effect on it. The problems were studied in the metatarsals of marsupials, insectivores, rodents and primates including Homo, and in various skeletal sections of wild and domesticated rats and dogs. No clear phylogenetic trend could be found and domestication cannot be shown to have an effect on diminishing skeletal robusticity. Sexual dimorphism of skeletal robusticity seems to be highly species-specific and to have a mosaic distribution in a given taxon. Conclusions on phylogenetic trends of sexual dimorphism of skeletal robusticity and the effect of culture on it seem to be premature.

Volumetric determination of metatarsal robusticity in a few living primates and in the foot ofOreopithecus

A new technique is described for the volumetric determination of metatarsal robusticity. Since volume was substituted for weight of a previously used technique, that technique is applicable to fossilized material. The comparability between the metric and volumetric techniques was tested and found to be sufficiently close to make the two techniques interchangeable. When the volumetric technique was applied to fourOreopithecus metatarsals, their robusticity was found to follow the 1→5 pattern (in which M5 is the least robust metatarsal), a pattern typical for all higher primates but present also inHomo. Their total robusticity was found to be closest toHomo and the gorilla, suggesting the likelihood of a terrestrial habitat forOreopithecus.

Relationship between facial protrusion and tooth length in four strains of rats.

Total tooth length was measured in the first lower molar of two short-faced strains of rats (Sprague-Dawley and Buffalo) and two long-faced strains (BN and GRL). Tooth length was significantly longer in the long-faced than in the short-faced strains. The same correlation had previously been found in dogs, baboons and human populations, as well as in rats in which facial shortening was obtained experimentally by septum removal. The data suggest that the same mechanism is responsible for this relationship in all groups.