The effects of antirat nasal septum cartilage antisera on facial growth in the rat.

Antirat nasal septum cartilage antisera (RNS-IgG) produced in rabbits by injection of crude antigens derived from rat nasal septum cartilage was cytotoxic for rat chondrocytes in vitro. The effect of this antisera on rat facial growth was tested by injecting three groups of growing rats at 4-day intervals from birth to 30 days. The treatment group (n = 19) received injections of RNS-IgG, one control group (n = 11) received injections of the IgG fraction of preimmune rabbit sera (PI-IgG) and a second control group (n = 16) received injections of normal saline. All animals were killed at the conclusion of the experiment, and lateral and dorsoventral cephalometric radiographs were taken. Statistical difference between treatment and control groups were found for 15 cephalometric measurements. Specifically, snout length (as measured from the intersphenoidal synchondrosis to the upper incisors (is-i) was reduced in animals treated with RNS-IgG compared with both PI-IgG and saline injected controls (p < 0.06, p < 0.005, respectively). In addition, premaxillary length, premaxillary displacement, and bimaxillary width were significantly reduced (p < 0.05) in RNS-IgG treated animals compared with saline injected controls. Bimolar width was reduced (p < 0.05) between RNS-IgG and PI-IgG groups. These results demonstrate that injection of antinasal septum antisera reduces midfacial dimensions in experimental rats and that nonimmune rabbit antisera may have an effect on the growth process. In summary, the results of this pilot study suggest the possibility for using more specific antinasal cartilage antibodies to effect dose-dependent, tissue specific, modulation of facial growth.

Systemic or intracranial apomorphine increases copulation in long-term castrated male rats.

Testosterone or its estrogenic metabolite is thought to be necessary to activate male rat sexual behavior. However, systemic injections of dopamine agonists, alone or in combination with exogenous testosterone, can partially restore copulatory behavior during the prolonged period of its postcastration decline. The present experiments tested the ability of the dopamine agonist apomorphine, injected systemically or into the medial preoptic area (MPOA), to restore copulation in long-term castrates that had failed to copulate on two successive weekly tests. In Experiment 1, systemic injections of apomorphine increased the number of mounts and intromissions in castrated males, compared to vehicle. In castrates given subthreshold testosterone propionate (TP), apomorphine increased the number of mounts. In Experiment 2, microinjections of apomorphine into the MPOA increased the number of mounts in animals without TP. Subthreshold TP had no significant effects in either experiment, either alone or interacting with apomorphine. These results suggest that stimulation of dopamine receptors can partially restore copulation, even after its virtual elimination. Furthermore, dopamine receptors in the MPOA may contribute to sexual arousal in long-term castrates.

D2/D1 ratio in the medial preoptic area affects copulation of male rats.

The D1/D2 dopamine agonist apomorphine, microinjected into the medial preoptic area (MPOA), facilitates male rat sexual behavior and the D1/D2 antagonist cis-flupenthixol in the MPOA impairs it. The present study investigated the roles of D1 and D2 receptors in the regulation of copulation by microinjecting drugs selective for these receptors into the MPOA. The D2 agonist LY-163502 delayed the onset and slowed the rate of copulation and also reduced the number of vaginal intromissions required to trigger ejaculation (reduced ejaculatory threshold). The D1 agonist SKF-82526 had no effect, either alone or together with LY-163502. The D1 antagonist SCH-23390 delayed the onset of copulation and decreased ejaculatory threshold, as had the D2 agonist. A low dose of the D2 agonist alone and together with the D1 antagonist delayed the onset of copulation and reduced ejaculatory threshold; the combination of drugs was more effective than LY-163502 alone. Only the combination of drugs slowed the rate of copulation and delayed the resumption of copulation after an ejaculation. Thus, increasing the D2/D1 ratio in the MPOA, by selective stimulation of D2 and/or antagonism of D1 receptors, delays the onset of copulation and reduces ejaculatory threshold, possibly by altering autonomic control of penile reflexes.

Histomorphologic evaluation of scleral grafts in experimental bony defects.

This study was undertaken in order to evaluate and compare the effectiveness and fate of the nonautogenous scleral graft in relation to similar grafts of bone marrow and epithelium-free connective tissue grafts from the palate. One hundred round osseous defects 2 mm in diameter, were surgically created in the calveria of 25 rats. Three defects in each animal were filled with the various graft materials obtained from isogenic rats sacrificed at the time of preparation of the bony defects. The fourth defect was left empty as a control. The animals were sacrificed at varying periods of time up to 150 days. Histomorphologic evaluation of the graft sites demonstrated the following: (a) Scleral grafts had effected a functionally adequate repair, without apparent histopathologic changes. (b) Fresh bone marrow provided the greatest osteogenic activity when used as a graft implant. The sclera had an insignificant osteogenic activity when used as a graft implant. The sclera had an insignificant osteogenic potential. (c) Epithelium-free connective tissue was the least effective, both as an osteogenic or functionally adequate graft.