Arthur M. Zimmerman

Effects of Cannabinoids on Sperm Morphology

Sperm morphology was studied in hybrid mice of genotype (C57BL X C3H)F1 following treatment with specific cannabinoids. Mice were treated for 5 consecutive days with the specific cannabinoid; 35 days after the last treatment, epididymal sperm were scored in the light microscope and assessed in the scanning electron microscope. The animals treated with delta9-tetrahydrocannabinol (delta9-THC) and cannabinol (CBN) had a statistically higher incidence of abnormal sperm than the controls. The incidence of abnormal sperm in the animals treated with cannabidiol (CBD) was not statistically different from the control value. The relative toxicity of the cannabinoids in these studies was delta9-THC greater than CBN greater than CBD. Normal sperm have a smooth kidney-shaped head with a prominent hook; abnormal sperm have shapes which include heads without hooks, banana-shaped heads, amorphous heads and folded heads.

Cannabinoid Receptors in Sperm

Mammalian and invertebrate sperm contain receptors for a wide variety of neurotransmitters that regulate sperm functions required for fertilization such as motility and the initiation of the acrosome reaction. The acrosome reaction is a ligand-stimulated secretory event in sperm that enables the sperm to penetrate the egg’s investments and to fuse with the egg’s plasma membrane. Previous studies in our laboratory using [3H]CP-55,940 showed that sea urchin sperm contain cannabinoid receptors that are remarkably similar to cannabinoid receptors found in mammalian brain and peripheral organs. Cannabinoid agonists and anandamide (an endogenous ligand for cannabinoid receptors in mammalian tissues) inhibit fertilization in sea urchins by blocking the acrosome reaction. These findings, taken together with other studies showing that the gene for the human brain cannabinoid receptor also is expressed in the human testis and that anandamide is synthesized in the female reproductive tract in mammals, suggested to us that human sperm may contain cannabinoid receptors. We have obtained preliminary evidence that [3H]CP-55,940 binds to putative cannabinoid receptors in live human sperm in a saturable manner, and that cannabinoid ligands affect in vitro capacitation of human sperm. These findings show that functional cannabinoid receptors are present in sperm, suggest that sperm cannabinoid receptors and their endogenous ligands may regulate normal sperm functions required for fertilization within the female reproductive tract in humans, and also imply that smoking marijuana may affect these processes in vivo.

THE EFFECTS OF SELECTED CHEMICAL AGENTS ON FURROW INDUCTION IN THE EGGS OF ARBACIA PUNCTULATA

Following high speed pressure-centrifugation treatment, fertilized eggs of Arbacia punctulata exhibit a furrowing reaction prior to cytokinesis. Fertilized eggs were incubated in metabolic and mitotic inhibitors and the effects of these agents on frequency, stability and position of the induced furrows were observed. Puromycin and p-fluorophenylalanine (inhibitors of protein synthesis), in concentrations which inhibit cytokinesis in control cells, did not prevent the induced furrowing reaction, although the frequency of furrow induction was reduced. Actinomycin D (an inhibitor of mRNA synthesis) had no effect on furrow induction. Heavy water and colcemid, at concentrations which block pronuclear fusion and cell division, did not block furrow induction. Mercaptoethanol treatment (at concentrations which block cytokinesis) did not reduce the frequency of induced furrows but resulted in less stable furrows and in shifting of the plane of furrow to an equatorial position. Agents that block oxidative phosphory...

ACTION OF HYDROSTATIC PRESSURE ON SEA URCHIN CILIA

The effects of hydrostatic pressure on the cilia of sea urchin embryos (Arbacia and Strongylocentrotus) were investigated. At a pressure of 10,000 psi the swimming blastula and early gastrula embryos became less active. They lost their translational movement and began to rotate slowly on the bottom of the chamber; in about 10 min all movement stopped and essentially all cilia had fallen from the embryos. At lower pressures and with longer durations the embryos were differentially affected and there was considerable variation in the number of cilia removed from individual embryos. With pressures of 6000 psi for 60 min the majority of the embryos lost more than 50% of their cilia. Arbacia embryos were more pressure-sensitive than Strongylocentrotus embryos.Following deciliation with hypertonic seawater, hydrostatic pressure above 5000 psi was found to block regeneration for the duration of the pressure treatment. At 6000 psi and above the regeneration delay was in excess of the duration of pressure treatmen...