Hubert W. Burden

Anatomical localization of afferent and postganglionic sympathetic neurons innervating the rat ovary.

The fluorescent retrograde tracer, True blue, was applied directly to either the superior ovarian nerve (SON) or the ovarian plexus nerve (OPN) in the rat. Afferent perikarya were located in lower thoracic-upper lumbar dorsal root ganglia and projected to the ovary via both nerve routes. Postganglionic sympathetic efferent perikarya were located in both prevertebral and thoracolumbar paravertebral ganglia and also utilized both the SON and OPN to reach the ovary. The significance of the dual origin of postganglionic sympathetic neurons innervating the rat ovary is not known.

Afferent fibers in the reproductive system and pelvic viscera of female rats: Anterograde tracing and immunocytochemical studies

Innervation of the female reproductive system provides an important signal for a variety of neuroendocrine reflexes and behaviors in the female rat. Although some studies suggest that afferent feedback from the gonads is involved in the hypothalamic control of gonadal function and pituitary hormone release, the extent and function of afferent feedback from the gonads in these neuroendocrine reflexes has yet to be clarified. Deafferentation studies have provided only partial support for the afferent control of the gonads. Some studies even suggest functional asymmetries in the neural control of the gonads, but knowledge regarding the neuroanatomical substrate for these possible neurogonadal interactions remains incomplete. Studies with retrograde tract tracers indicate that the ovaries receive a substantial afferent supply from lower thoracic-upper lumbar dorsal root ganglia. Despite stringent precautions to prevent diffusion of tracers following injections into the ovary or related nerves, many of the retrogradely labeled cell bodies identified by these studies may represent an overestimation of the extent of afferent innervation. We have reexamined the afferent innervation of the female reproductive tract by means of the anterograde transport of horseradish peroxidase (HRP) from thoracic, lumbar and sacral dorsal root ganglion to pelvic visceral organs and have studied the effects of unilateral ganglionectomy on substance P containing fibers in the ovary, oviduct and uterus. The neuroanatomical results show that the T13 and L1 dorsal root ganglia provide major afferent innervation to the cranial portion of the reproductive tract and the L6 and S1 dorsal root ganglia provide primary afferent fibers to the caudal portion of the reproductive tract as well as the bladder, rectum and perineum.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Denervation on Compensatory Ovarian Hypertrophy

Hemiovariectomized rats were randomly assigned to 1 of 5 groups: controls, 6-hydroxydopamine (6-HD)-treated, abdominal vagotomy, 6-HD-treated plus abdominal vagotomy and pelvic parasympathectomy. 15 days later all animals were sacrificed and the amount of compensatory ovarian hypertrophy (COH) was calculated. Vagotomy and vagotomy plus 6-HD treatment interrupted estrous cycles and significantly decreased COH. Vagotomized rats with both ovaries intact had disrupted estrous cycles but ovarian weights were not affected. In a subsequent study, rats in estrus were sham-operated, unilaterally ovariectomized (ULO), vagotomized, or vagotomized + ULO, and serum levels of LH and FSH were determined at 5 and 24 h. ULO caused a significant (p less than 0.05) increase in LH and FSH at 5 h. Vagotomy significantly (p less than 0.05) depressed LH and FSH levels in hemiovariectomized animals at 5 h. By 24 h LH was significantly higher in ULO than in either sham-operated (p less than 0.05) or vagotomy (p less than 0.01) groups. Also, vagotomy significantly (p less than 0.01) depressed FSH levels at 24 h. These results suggest a functional role for the vagus nerve in normal cyclic activity, COH, and gonadotrophin (Gn) secretion.

Cholesteryl Ester Transfer Protein Expression Prevents Diet-Induced Atherosclerotic Lesions in Male db/db Mice

Objective—Accompanying more atherogenic lipoprotein profiles and an increased incidence of atherosclerosis, plasma cholesteryl ester transfer protein (CETP) is depressed in diabetic obese patients compared with nondiabetic obese counterparts. The depressed levels of CETP in the plasma of diabetic obese individuals may contribute to the development of an atherogenic lipoprotein profile and atherogenesis. We have examined the effect of CETP expression on vascular health in the db/db model of diabetic obesity. Methods and Results—Transgenic mice expressing the human CETP minigene were crossed with db/db strain, and 3 groups of offspring (CETP, db, and db/CETP) were placed on an atherogenic diet for 16 weeks. The proximal aorta was then excised and examined for the presence of atherosclerotic plaques. In db mice, 9 of 11 had intimal lesions with a mean area of 26 098±7486 &mgr;m2. No lesions greater than 1000 &mgr;m2 were observed in db/CETP or CETP mice. CETP-expressing mice had lower circulating cholesterol concentrations than db mice. Fractionating plasma lipids by FPLC indicated that the difference in total cholesterol was primarily attributable to differences in VLDL and LDL. Conclusions—The expression of human CETP in db/db mice prevented the formation of diet-induced lesions, suggesting an antiatherogenic effect of CETP in the context of diabetic obesity.

Anti-cancer drug induced neurotoxicity and identification of Rho pathway signaling modulators as potential neuroprotectants

Many chemotherapy drugs are known to cause significant clinical neurotoxicity, which can result in the early cessation of treatment. To identify and develop more effective means of neuroprotection it is important to understand the toxicity of these drugs at the molecular and cellular levels. In the present study, we examine the effects of paclitaxel (taxol), cisplatin, and methotrexate on primary rat neurons including hippocampal, cortical, and dorsal horn/dorsal root ganglion neuronal cultures. We found that all of these anti-cancer drugs induce substantial neurotoxicity evidenced by neurite degeneration. The neurons are capable of recovering after treatment withdrawal, but taxol exerts a biphasic effect that results in the collapse of processes days after treatment is withdrawn. After cisplatin and methotrexate treatment, we observed the degeneration of neuronal processes including the reduction of dendritic branching, length, and altered growth cone formation, indicating an abnormal arrangement of the actin cytoskeleton consistent with the involvement of Rho family small GTPases. Inhibiting RhoA downstream effector p160 ROCK/Rho kinase using Y-27632, or activating p75 neurotrophin receptor (p75 NTR) using non-peptide mimetic LM11A-31, were able to reverse the degeneration caused by cisplatin and methotrexate. Therefore, the neurotoxicity resulting from exposure to the anti-cancer drugs cisplatin and methotrexate can be alleviated by inhibiting Rho signaling pathway.

Substance P- and vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers in relation to ovarian postganglionic perikarya in para- and prevertebral ganglia: Evidence from combined retrograde tracing and immunocytochemistry

SummaryRetrograde neuronal tracing with the fluorescent dye True Blue and immunocytochemistry were utilized to examine postganglionic sympathetic neurons in para- and prevertebral ganglia projecting to the rat ovary. Perikarya in both ganglia were labeled with True Blue after application of the tracer to either the superior ovarian or ovarian plexus nerve. After application of True Blue to the superior ovarian nerve, 17% of the labeled cells in paravertebral ganglia were immunoreactive for vasoactive intestinal polypeptide. In contrast, after application of True Blue to the ovarian plexus nerve, approximately 1 % of the labeled cells in paravertebral ganglia were immunoreactive for the same polypeptide. Some vasoactive intestinal polypeptide-immunoreactive perikarya in paravertebral ganglia were not labeled with True Blue. In some cases, substance P- and vasoactive intestinal polypeptide-immunoreactive fibers were closely apposed to True Blue-labeled perikarya in para-and prevertebral ganglia. Paravertebral vasoactive intestinal polypeptide-immunoreactive perikarya projecting to the ovary presumably participate directly in the control of various ovarian functions. Substance P- and vasoactive intestinal polypeptide-immunoreactive fibers closely apposed to perikarya projecting to the ovary may participate indirectly in the control of various ovarian functions by affecting the activity of ovarian postganglionic neurons.

Effects of Abdominal Vagotomy on the Estrous Cycle of the Rat and the Induction of Pseudopregnancy

Abdominal vagotomy of estrus or proestrus rats resulted in disruptions of the estrous cycle which was characterized by prolonged periods of diestrus (10-12 days in length). In contrast, vagotomy on metestrus or diestrus did not disrupt the estrous cycle. The induction of pseudopregnancy, in response to cervical stimulation on the morning of estrus, was also interrupted by abdominal vagotomy. The nocturnal and diurnal prolactin surges and elevations in serum progesterone, characteristic of pseudopregnancy, were prevented by vagotomy. Vagotomy, also, largely prevented the formation of deciduoma in response to traumatization of the uterus in cervically stimulated rats.

The effects of denervation on the localization of ▵5-3β-hydroxysteroid dehydrogenase activity in the rat ovary during pregnancy

The effect of denervation on △5-3β-hydroxysteroid dehydrogenase (3β-HSD) activity with pregnenolone as substrate was studied during pregnancy. The enzyme activity, that is interpreted as the capacity to secrete progesterone, was studied in both control and experimental pregnant rats. The ovaries of experimental rats were denervated 96 h prior to sacrifice. Denervation during early pregnancy did not affect 3β-HSD activity in the interstitial gland (IG) and corpus luteum (CL). However, denervation resulted in decreased activity in both the IG and CL on days 10, 14 and 18. This reduced activity is interpreted as a decreased capacity of denervated ovaries to synthesize progesterone at this time in pregnancy.

Effects of peripheral nerve lesions during pregnancy on parturition in rats

SummaryBilateral section of either the sensory or motor branch of the pelvic nerve or pudendal nerve was performed in rats on days 8–10 of pregnancy, and the effects on delivery were observed. Bilateral resection of the sensory branch of the pelvic nerve reduced the number of live pups per litter, and increased the number of stillbirths and the number of fetuses retained in utero per litter at day 24. Sectioning motor components of the pelvic nerve, or both motor and sensory components of the pudendal nerve, had no effects on delivery in rats. We conclude that of the peripheral nerves evaluated in this study, only the sensory branch of the pelvic nerve is required for normal vaginal delivery in this species.

NADPH-diaphorase-positive neurons innervating the rat ovary.

Nerve cell bodies projecting to the ovary were visualized in dorsal root ganglia (DRG) and paravertebral ganglia after application of the retrograde tracer Fluoro-gold to the superior ovarian and plexus nerves. The location of fluorescent cells in sections of ganglia was recorded and subsequently nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry was utilized to locate nitric oxide synthase (NOS) whose presence indicates sites where nitric oxide (NO) can be synthesized. No fluorescent nerve cell bodies in paravertebral ganglia were NADPH-diaphorase-positive. In contrast, numerous Fluoro-gold-labeled nerve cell bodies in DRG at segmental levels T12-L1 were NADPH-diaphorase positive. Thus, many sensory neurons projecting to the ovary contain NOS and presumably release NO. This gaseous messenger molecule may participate in modulation of ovarian function.